DK EYEWITNESS TREE

Eyewitness

(c) 2011 Dorling Kindersley. All Rights Reserved.

Eyewitness

Tree

(c) 2011 Dorling Kindersley. All Rights Reserved.

Rowan berries
and leaves

Blue
atlas
cedar

Weymouth
pine cone

Acorns Apples
Magnolia
leaf

Monterey Willow
cypress Hazelnuts

Victoria plum fruit

Ginkgo leaf

(c) 2011 Dorling Kindersley. All Rights Reserved.

Sycamore seeds Eyewitness Ornamental apple fruit

Tree

Written by

DAVID BURNIE

Lodgepole Ash leaf Fungus feeding
pine cones Hazelnuts on decaying
wood
Oak wood
Moss on
decaying wood

DK Publishing, Inc.

(c) 2011 Dorling Kindersley. All Rights Reserved.

Lawson cypress cones Western
Wellingtonia cone red cedar leaves

Pine cone

Japanese London, New York, Pear
maple leaf Melbourne, Munich, and Delhi
Larch cones Rowan leaf
Series editor  Janice Lacock
Variegated Art editor  Carole Ash Young Scotch
holly leaf Special photography pine cones

Peter Chadwick, Philip Dowell, and Kim Taylor Vine-leaved
Editorial consultants maple leaf

The staff of the Natural History Museum, London Osier leaf

Revised edition
Managing editors  Linda Esposito, Andrew Macintyre

Managing art editor  Jane Thomas
Senior editor  David John

Project art editor  Joanne Little
Editor  Sarah Phillips

Art editor  Rebecca Johns
Production  Luca Bazzoli
Picture research  Sean Hunter
DTP designer  Siu Yin Ho

U.S. editors  Elizabeth Hester, John Searcy
Publishing director  Beth Sutinis
Art director  Dirk Kaufman
U.S. DTP designer  Milos Orlovic

U.S. production  Chris Avgherinos, Ivor Parker

This Eyewitness ® Guide has been conceived by
Dorling Kindersley Limited and Editions Gallimard

This edition published in the United States in 2005
by DK Publishing, Inc.

375 Hudson Street, New York, NY 10014

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Copyright © 1988, © 2005, Dorling Kindersley Limited

All rights reserved. No part of this publication may be
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Published in Great Britain by Dorling Kindersley Limited.

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available from the Library of Congress.

ISBN 0-7566-1093-1 (Hardcover) 0-7566-1094-X (Library Binding)

Color reproduction by
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(c) 2011 Dorling Kindersley. All Rights Reserved.

Contents Yew leaves

6 Hemlock
What is a tree? cones

8 Ginkgo leaf
Broadleaved trees
44
10 Cones
Coniferous trees
46
12 Falling leaves
Tropical trees
48
14 The death of a tree
The birth of a tree
50
16 Life among the leaves
How trees grow
52
18 Life in the leaf litter
Putting down roots
54
20 Pollution and disease
The tree trunk
56
22 From tree to timber
Bark – the outer skin
58
24 Working with wood
From bud to leaf
60
26 Tree care and management
Simple leaves
62
28 Looking at trees
Compound leaves
64
30 Did you know?
Needles and scales
66
32 Identifying trees
Blowing in the wind
68
34 Find out more
Insect-pollinated flowers
70
36 Glossary
Animal-pollinated flowers
72
38 Index
Fruit and berries

40
Seeds and nuts

42
Tropical fruit and nuts

(c) 2011 Dorling Kindersley. All Rights Reserved.

What is a tree?

HOMAGE IN STONE The earliest “plants” were so small that it would have taken dozens of
This tree goddess was
carved on a Hindu them to cover a pinhead. These tiny cells lived in the oceans of the ancient
shrine in India, Earth, and the only thing that enables us to classify them as plants was that
c. 150 a.d. they could use sunlight to grow. From these humble beginnings, the whole
plant kingdom as we know it today has evolved. Many plants remained in
water, but others began to grow on land. To do this successfully, they needed
a way to support themselves. Some plants eventually developed a material
called lignin, which made their stems tough and woody so that they could
grow taller. Because all plants need light, the tall plants did better than the
small ones, which had to survive in their shade. In time, plants with a giant
single stem appeared: these were the first trees. Since then trees have evolved
many times, in different families of plants. The bulkiest - the giant sequoias of
California - can weigh more than 6,000 tons, making them the heaviest living
things ever to have existed on Earth.

Spreading base connects tree Rugged, cracked Broken branch may
to a circle of roots (pp. 18-19) bark (pp. 22-23) at allow fungi to
that anchors it in ground base of tree penetrate trunk

Trunks (pp. 20-21) are
longest and straightest
in trees grown close
together

The tree in mythology NORSE LEGEND
In Scandinavian
All over the world, from the dark forests of Scandinavia to the myths, Yggdrasil
banyan groves of India, trees have figured in ancient myths, is a mighty ash
folklore, and rituals. Perhaps because of the size and long life of tree, peopled by
trees, many religions have regarded them as sacred symbols, and fabulous animals
certain individual trees have been worshiped as gods. Hindus, for and giants, which
example, revere the banyan links the earth
tree; the Druids with heaven and
worshiped the oak. hell. Like many
trees of legend it is
CHRISTIAN BELIEF also a source of
In the Bible, the cross knowledge: the
on which Christ died god Odin gained
was symbolically linked his wisdom by
drinking from the
with the tree of life, spring at its roots.
which grew in the

garden of Eden along
with the tree of

knowledge and offered
everlasting life.

(c) 2011 Dorling Kindersley. All Rights Reserved.

TREE OR NOT?
A tree is a tall plant
with a single woody
stem. The three main
groups of trees are the
broadleaves (pp. 8-9),
the conifers (pp. 10-11),
and the palms (pp. 12-
13). There are several
other treelike plants,
including tree ferns,
cycads, and giant
bamboo (shown
here).
Bark becomes
smoother higher
up the tree

Each spring, twigs,
leaves, and flowers
(pp. 32-37) develop
from buds (pp. 24-25)

Branches stay at
same height above
ground as tree grows,
becoming thicker
each year

DAPHNE In summer, deciduous
TRANSFORMED trees have a dense
Greek legend has it canopy of leaves
that to escape from (pp. 26-31)
the amorous Apollo, the
goddess Daphne changed into a
laurel tree. Today the laurel has a
symbolic use as a token of victory,
just as it did in ancient Greece.

(c) 2011 Dorling Kinde rsley. All Rights Reserved.

Broadleaved trees

Five thousand years ago, before the
spread of agriculture, huge areas of Europe
and eastern North America were cloaked in
broadleaved forest. Since then much of the
forest has been cleared to make way for
people. Despite this, woodlands with stately broad­
leaved trees such as oaks, beeches, and maples still remain
Hedge maple in many places and make up an extremely important

natural habitat. Broadleaved trees are so named because most of them
have broad, flat leaves, quite unlike the needles and scales of conifers.
They all produce flowers, and after pollination (pp. 32-37) these flowers
develop seeds. The seeds are often enclosed in a hard
nut or a fleshy fruit. Many broadleaved trees shed
their leaves every autumn: that is, they are
deciduous (p. 46).

Young acorns BROADLEAVED WOODLAND
attached to Natural woodlands are powerhouses of biological
long stalks activity. The trees’ leaves intercept sunlight and use
it to provide the energy they need to grow (p. 16).
Every year they produce huge quantities of wood,
leaves, flowers, fruit, and seeds. These make up the

food of millions of woodland
animals that range from tiny
invertebrates (animals without
backbones), such as micromoths
(p. 51), to large mammals, such as deer.

Oak in winter Oak in full
summer
foliage

THE OAKS THE WINTER SLEEP Lichen
Oaks are typical broadleaved trees. Broadleaved trees are most common in growing
About 600 species are found around on bark
the world. Some oaks, like the warm climates. To survive in colder
English oak shown here, are Young acorns on regions, they have evolved a form of
deciduous; others are evergreen. All long stalks “hibernation” in which they shed
oaks are wind pollinated (p. 32), their leaves and become
and all produce acorns. Oak wood is dormant (inactive)
exceptionally hard and durable. until spring.

Narrow
growth
rings

Hard wood, resistant Leaf litter, rich in rotting fungi
to decay and invertebrate animals

(c) 2011 Dorling Kindersley. All Rights Reserved.

Crooked branches SHAPED BY THE ENVIRONMENT
grow at irregular A tree’s position can affect its
intervals shape. In windswept places,
Irregular shape caused by twigs and branches on the side
strong winds facing the wind are killed, so a
tree becomes lopsided. A tree
growing close to others grows
mainly upward as it reaches for
light; a tree in the open forms a
leafy, spreading crown.

A beech growing in Beeches growing on a
an open site plantation

BROADLEAVED GROWTH PATTERNS Broad, leathery leaves
Broadleaved trees like oaks generally in clusters at tips of
have a spreading growth pattern. In most shoots
species the trunk divides into many
spreading branches of similar size. (c) 2011 Dorling Kindersley. All Rights Reserved.
This is quite unlike the more upward
growth of conifers (p. 10).

Coniferous trees

Conifers grow all around the world,

but particularly in the colder regions.
They encircle the far north in a band of
continuous forest that stretches across North
America, Scandinavia, and Siberia. Where high
mountains reach southward, conifers can be found
clinging to the steepest slopes. They are an ancient
group of plants, and fossils show that their range
was once much wider than it is today. Coniferous
trees generally have narrow, hard leaves that are
Norway spruce known as scales or needles, depending on their

shape. Nearly all of them are evergreen.
Conifers do not have true flowers; instead,
they produce cones.

VARIATIONS IN SHAPE CONIFEROUS FOREST
Although many Where conifers are grown close together in
conifers, like the cypress plantations, the year-round shade they cast
or Norway spruce, have
an upright, conical makes the forest a poor place for wildlife.
shape, others, like the But in a natural coniferous forest
yew and Scotch pine, containing large, mature trees, spaces
have a fuller profile. between the trees allow other
plants to grow. This provides
food for a variety of animals
and invertebrates.

Scotch pine Cypress

THE PINES Irregular branching
There are nearly 100 found only in
species of pine. Most of old trees and
them are found in cold
climates, although those growing in
some grow around the exposed places
Mediterranean and in
other warm regions. Young seed-bearing cones Mature seed-bearing cones
Pines are typical of Scotch pine Wide growth rings
conifers: their leaves
are narrow needles, Pine needles in leaf litter Resinous wood
and their seeds de­­
velop in hard cones.
Pine wood is gener­
ally fairly soft and
contains a strong­
smelling resin that
helps to prevent decay.

(c) 2011 Dorling Kindersley. All Rights Reserved.
10

Bark at the top of a
mature Scotch
pine flakes off
in thin, reddish
patches

New female cones
take almost two years

to ripen and shed
their seeds.

Hard blue-green
needles carried in
pairs around the
sides of the shoots

CHRISTMAS CONIFERS    CONIFER GROWTH PATTERN
Although trees have In most young conifers there is a
been used as ornaments strong leading shoot, and short side branches
for hundreds of years are thrown out at regular intervals. Later in life
at Christmas, the their growth may become much less symmetrical
custom of decorating (even), as the gnarled and twisted branches of
Norway spruces and this Scotch pine show.
other conifers became
really widespread in the 19th
century. Evergreen decorations,
however, were used long before
the arrival of Christianity: in pagan
midwinter festivals the green
foliage of holly or conifers signaled
the return of spring.

(c) 2011 Dorling Kindersley. All Rights Reserved.
11

Tropical trees

Although tropical trees do not have to face harsh
winters, their growth is affected by another factor - rain. In
some parts of the tropics, rain falls all year round. In these
hothouse conditions, broadleaved trees can grow at an
extraordinary rate - 15 ft (5 m) a year is quite common for some
saplings. So crowded are the trees that, area for area, tropical rain
forest supports the biggest weight of living matter of any land
habitat on Earth. Where there is less rain, trees struggle
Palm more against drought than against each other. In

places with wet and dry seasons, many trees shed their leaves to
survive the water shortage. Trees like palms and eucalyptuses,
which often live in places that are very dry, often have tough,
leathery leaves to keep hot winds from drying them out.

BUTTRESS ROOTS BENEATH THE CANOPY
In tropical rain forests, trees often In tropical rain forest, the unbroken “canopy”
grow to great heights to compete formed by the treetops casts a deep shade
with their neighbors for sunlight. on the forest floor.
Where the soil is thin, the trees are in
danger of toppling over, so some
species have evolved
buttress roots that
spread out and stabilize
their trunks.

NATURAL DRAINAGE Drip tip throws off
Many tropical trees have leaves rainwater
with pointed tips. These work like
gargoyles on old buildings,
throwing off the water in heavy
downpours. The tree shown here is
a weeping fig, which is found in
India and southeast Asia.

(c) 2011 Dorling Kindersley. All Rights Reserved.

RECORD-BREAKING
EUCALYPTUSES
Eucalyptuses are some
of the fastest-growing
trees in the world. They
are mainly found in the
parched outback and subtrop-
ical forests of Australia; some
species also grow near the

snow line on
the continent’s
mountains.

ISLAND JUNGLE
This dense tangle of vegetation is
typical of the rain forest of northern
Australia. Cooler forests in Australia
and New Zealand are the home of
many species of tree ferns, plants
that look like palms but are quite
unrelated to them.
Tree fern

Leaves unfold like
fans as they grow

Single, THE ONE-TREE FOREST Eucalyptus leaves
fibrous The banyan is an extraordinary tropical tree contain oil and
unbranched that spreads by forming pillar roots. These attract koala bears
stem develop from roots that grow down from the (p. 51)
banyan’s branches. One banyan in Calcutta
Each nut is has over a thousand pillar roots, giving it the
surrounded largest spread of any tree on Earth.
by a
waterproof, THE PALMS
lightweight There are just under 3,000 species
husk of palms in the world, nearly
Roots all of them found only in the
emerge tropics. The coconut palm’s
through nuts float on seawater until
husk they are thrown up on land.
The liquid or “milk” in the nut
allows the seed to germinate
on dry beaches.

(c) 2011 Dorling Kindersley. All Rights Reserved.
13

The birth of a tree

For any tree, the first few months of 5SHEDDING THE
life are far more hazardous than the SEEDCASE
decades, or even centuries, that follow Fourteen days after
them. While it is true that “tall oaks from germination the two
little acorns grow,” only a tiny fraction of seed leaves, or
a tree’s seeds actually survive that long. In cotyledons, expand.
a good year a single oak tree will produce These were previously
about 50,000 acorns. But most of these folded inside the seed,
will be eaten by animals or fall to places but now they force
Mature beech tree, over 150 years old, where they cannot grow. Those that do the seedcase off, and it
growing in parkland develop into seedlings run the risk of drops to the ground.
Until this moment,
being eaten or trampled on by animals. Only a handful will still be alive the seed has relied
a year later. All seeds have a store of food that entirely on its internal
provides energy to keep them alive and to fuel food reserves - now its
germination and growth. In some seeds, like 4GROWING UP seed leaves will start
those of willows, this store is so tiny that the Five days after to provide it with
germination, the energy.
seedcase has been Seedcase forced off by
lifted off the ground seed leaves
seeds must germinate within days of being by the developing
shed. On the other hand, the seeds of trees stem. As the root Emerging
like the oak and beech contain enough food to grows deeper into the seed leaves
stay alive for a whole winter. Germination - the ground, rootlets start
real birth of the tree - begins as soon as the to branch out just
below soil level.

days grow warmer in the spring. Seedcase

Seedcase Three-sided Crack
curling back seed attached caused by
to case swelling
embryo Seedcase Stem Stem
Soil level
1THE FALL TO EARTH Seedcase Emerging Rootlets
The beech tree root Rootlets Main
produces its seeds, 2GERMINATION Main root root
also called beech mast BEGINS 3GETTING A GRIP
or beechnuts, in During the winter The developing
woody cases. The tree months many of the embryo needs a firm
grows a heavy crop in seeds that lie scattered foothold in the ground.
“mast years,” which under a beech tree are A root appears from
occur about one year eaten by hungry the pointed end of the
in three. Some seeds squirrels, wood mice, seed and grows directly
drop when the woody finches, and jays. Those downward. It collects
cases open while still seeds that are lucky water and minerals
attached to the tree, enough to survive from the soil and
and others fall to the begin to germinate in anchors the seed.
ground while still early spring. The first
attached to the case. sign of life is a crack in
the seed’s hard shell as
the embryo inside it
begins to expand.

(c) 2011 Dorling Kindersley. All Rights Reserved.
14

6REACHING for 7COMING INTO 8THE SEEDLING IN SUMMER True leaves
LIGHT LEAF Fifty days after germination,
Once the seed leaves A month after the seedling has completed most
have unfolded, events germination, the seed of the growth that it will make in
start to move quickly. leaves are still powering its first year. If it survives the
The twentieth day the seedling’s growth, winter, it will begin its
after germination finds but the first true leaves second year with buds,
the seedling with a are beginning to expand. bark, and a tiny woody
shoot tipped by its first Unlike the stubby seed “trunk” - making it a
true leaves. With a leaves, the true leaves are complete tree in
great deal of luck, this just like those on the miniature.
slender shoot will adult tree. Below ground,
eventually become the the root
massive trunk of a system
mature tree. But if the has
seedling is growing become
under the deep shade much more
of its parent, the extensive.
young leaves will not
be able to provide True leaves with veins
enough energy, and as in adult tree
so, starved of light, the
seedling will die.

Developing shoot

Seed leaves will
wither at end of
first year

Stem Stem Stem

Seedcase Seedcase Seedcase
Main root Main root
Main root Rootlets
Rootlets Rootlets

(c) 2011 Dorling Kindersley. All Rights Reserved.
15

How trees grow

Trees grow in two different ways. At the tip
of every twig there is a group of specialized cells.
When these cells divide they make the twig grow
longer, and so the tree grows taller or spreads
more. At the same time, a different kind of growth
A LIVING SKIN is produced by the cambium, a layer of cells that
Despite losing its
heartwood inside, this
ash tree survives. It is covers the woody part of the tree. As the cells in
the outer layer of the cambium divide, the trunk, branches, twigs,
sapwood that carries
water and sap. and roots grow fatter. The girth of, or distance
around, most mature tree trunks increases by
roughly 1 in (2.5 cm) every year. In temperate climates, both kinds
of growth usually occur in the spring and summer only. The HIDDEN STRENGTH
cambium grows outward and the new cells that it produces form a As trees grow, the force produced
visible ring - one for each year. By counting these rings, it is by their expanding roots is
possible to figure out the age of the tree. tremendous. This tree in Cambodia
is gradually breaking up the old
temple wall on which it grows.

THE HEAVIEST TREES Heartwood - Sapwood - composed
Sequoias and California composed of living cells
redwoods grow on
mountainsides mostly of
watered by fog that dead cells
rolls in from the Sapwood -
Pacific Ocean. Because composed of
there are few strong living cells
winds, the trees’
growth is not stopped,
and they often reach
exceptional heights.

Bark

GROUND HUGGERS SLOW GROWTH FAST GROWTH
In the Arctic tundra, This branch from a yew This branch from a
conditions are too tree is over 75 years sycamore tree is only
severe for trees to old. Its growth rings are about 15 years old. Its
grow. Instead, packed closely together. growth rings are
flattened shrubs, widely spaced.
like this dwarf Area of
willow, flourish. rapid growth Area of
slow growth

Sap stain in partially LOPSIDED
seasoned wood GROWTH
As trees grow, their
THE OLDEST TREES Bark trunks and branches
Bristlecone pines are do not always
among the oldest living expand at the same
things on Earth. These rate all the way
pines grow in the around. Off-center
Rocky Mountains; at growth rings like these
high altitudes their can be produced in two
growth is extremely different ways. If a tree grows
slow. Some specimens in an exposed place, its wood
are estimated to be grows faster on the side facing away
6,000 years old. from the wind than it does on the
windward side. With large branches, faster
growth often occurs on the underside to help
support the weight of the branch.

(c) 2011 Dorling Kinders1le6y. All Rights Reserved.

THE YEARLY CYCLE OF GROWTH New leaves Sapwood Heartwood
For a few weeks every year in grow every year Cambium - region Growth ring
temperate-region trees, the growth Twigs grow of growth produced
produced by the cells at the tips of longer at every year
branches is very rapid. So too is the their tips Medullary ray -
growth of leaves as they expand carries nutrients
after emerging from their buds Trunk and branches inward
(p. 24). The growth in a tree’s girth grow thicker every year
is less noticeable, but it is just as Roots grow longer Bark
important: this type of growth is at their tips and
essential if the tree is to support the produce root hairs Sapwood - composed
extra height and spread that it gains every year (p. 19) of living cells
every year.
Roots grow
The branches and roots can grow thicker every
longer only at their tips, not farther year
back. This has an important effect Heartwood -
on tree growth: it means that once composed mostly
a branch has grown out from the of dead cells
trunk, it will always be at the same
height above the ground. Because
the trunk can only get fatter, not
longer, it cannot lift the branches
upward as the tree grows older. But
branches near the ground drop off
as the tree grows, so it can seem as
if the lowest branches are gradually
being lifted upward.

A CENTURY OF Narrow rings show
GROWTH that growth was
This trunk from a giant slower here
sequoia is about 100
years old. The girth of
this species can
increase by up to 3 in
(8 cm) every year.

Wide rings show
that growth was
rapid here
Fibrous bark
made up of
dead cells

(c) 2011 Dorling Kindersley. All Rights Reserved.

Putting down roots

Because trees are the tallest living plants, it is
easy to think that their roots plunge down deep into the
earth. But this is often far from the truth. Instead of
Badgers pass their tunnels on from growing downward, most of a tree’s roots grow
generation to generation. As a tree outward, forming a crisscrossing net that anchors the
grows, a badger “set” grows with it, tree in the ground. The roots of a tree 165 ft (50 m) tall
as the animals harmlessly dig new are likely to reach no more than 8 ft (2.5 m) into the
tunnels among the spreading roots

ground, but they may well spread outward to a distance that matches the
tree’s height. This means that the roots of a 165-foot tree cover an area the
size of a very large football field. Over all this ground, tiny root hairs
collect water and minerals and channel them into rootlets. The
precious water passes from the rootlets into the main roots and
finally, after a long journey, into the trunk.

Roots for waterlogged ground

Most trees are unable to grow MANGROVE SWAMP
in ground that is perma­ Mangroves face little competition from other plants.
nently waterlogged because On some tropical coasts they form bands of vegetation
the soil is unstable and hundreds of miles long.
moves around. It is also very
low in oxygen, which tree COMING UP FOR AIR
roots need. A few trees can The bald cypress
live in these conditions.
Mangroves are tropical trees flourishes in the bayou
that grow on coastal mud country of the southern
flats. They have two
special kinds of roots: stilt­ United States. It has
roots arch from the man­ two unusual
grove’s trunk and anchor the
tree in mud; breathing roots, characteristics - its
or pneumatophores, grow up knobbly breathing
through the mud and are roots, and the fact that
exposed to the air at low it is a deciduous conifer.
tide, enabling them to
collect oxygen. The bald
cypress is another tree that
has breathing roots. This
unusual conifer lives in the
freshwater swamps of the
southern United States,
where there is little oxygen
in the still water.

(c) 2011 Dorling Kindersley. All Rights Reserved.
18

THE GROWTH OF A ROOT Root hairs
For trees in temperate areas (where winter is the coldest
season), the yearly cycle of growth begins with the roots. As Zone of growth
the ground begins to warm up in spring, the roots grow Reinforced root cap
millions of tiny hairs, each of which is a single cell. These hairs is pushed forward
absorb water and moisture from the soil. Each root hair lives through soil
only a month or two, and in the autumn all the root hairs die.
At the tip of each root is a root cap, a layer of cells that protects
the root as it grows forward. Most of the tree’s nutrients are
absorbed by young roots; old roots become tough and woody
and are used for anchorage instead.

UNDERGROUND PARTNERSHIPS
Many tree roots grow intertwined
with the thin living threads, or

hyphae, of a fungus. The
colorful fly agaric
mushroom usually
grows among
birch and
pine roots.

LEAF CARRIERS
Earthworms are important to trees
because their burrows let air into

the soil around the roots.
They also drag fallen leaves
underground, returning
minerals to where the
roots can reach them.

LIVING UNDER ROOTS
Burrowing animals such as
rabbits and badgers often set
up home under trees. The
roots keep the ground
from collapsing and
also remove some of

the moisture,
making the
ground
drier.

(c) 2011 Dorling Kindersley. All Rights Reserved.
19

The tree trunk THE SPIRAL CREEPER
Tree creepers are small
Just below the surface of a tree’s trunk, mouse-colored birds
that feed on tree-trunk
constant but invisible flows of sap draw insects. They are
minerals up from the ground and carry unique in the way
nutrients downward from the leaves (p. 17). they climb each
The tree guards this rich pathway for food with its covering trunk by spiraling
of tough bark. Even so, insects, fungi, and parasitic plants around it.
sometimes manage to break through this barrier and reach Hole in dead wood
what lies beneath. Nourished by the food that they have dug by a wood­
plundered from the tree, these animals form the base of the pecker and used for
tree-trunk food chain. Fungi rot the wood and open it to nesting; the
other attackers, while the larvae of countless insects, from surrounding bark
beetles to wood wasps, make up the food of woodland birds. has healed
after a small
THE LIVING LARDER branch
Many mammals, such as squirrels, dropped
take away tree seeds and bury away
them. But they do not find later all
the seeds they have stored, and Acorns in pine bark Acorn wood-
many of these seeds survive to pecker on a
germinate. The acorn woodpecker tree trunk
of south-western America stores
acorns in an obvious place - in trees
or telegraph poles. It bores holes
and pushes an acorn into each one.
It may cover a single tree with
hundreds of holes.

Green coloration on
bark caused by a

thick layer of tiny
single-celled plants
called algae, which
reach the trunk by
wind-blown spores
Living bark growing over
dead heartwood

Fruiting bodies of “Eye” in bark -
fungus - it has in- the scar left by
fected damp wood a young branch
LIFE ON THE TRUNK that was shed
This trunk is from a mature Norway maple. Fungi
and insects will attack where dead wood is ex-
posed, but the tree will survive as long as enough
living wood is left to supply water to the leaves.

(c) 2011 Dorling Kindersley. All Rights Reserved.

Nuthatch and TREE-TRUNK ACROBATS
young Although most large birds cannot
support their weight while clinging
Cross section of to a vertical tree trunk, smaller
nuthatch nest species have no difficulty doing so.
Their agility enables them to collect
rich pickings in the form of insects
that live in bark crevices. Many of

these birds fly from
tree to tree,
working their way
upward as they
quickly scan the
trunk for food. The
nuthatch is alone
among them in
being able to walk
down a trunk as
well as up it.

Bark damaged IMPRISONED INSIDE A TREE
by squirrels in Some birds that nest in tree-trunk
search of the holes adapt the entrance size and
tree’s sugar- shape by adding mud to it. This
rich sap habit is taken to extremes by
tree hornbills. The female
Healthy seals the nest entrance with
side branch a mixture of mud and sa­
with complete liva, leaving just a small
bark covering hole so that her mate can
Side galleries feed her. The mud en­
dug by growing trance dries to become very
larvae hard, preventing predators
from breaking in to attack
the mother and fledglings.
While she is trapped inside
her cell, the female bird
molts, and may be almost
bald for some weeks.

Eggs laid at Bark beetles Pine weevil
intervals INSECT MINERS WOOD BORERS
The young of bark Adult weevils can
along main beetles dig spread disease and
gallery galleries as they damage shoots by
eat their way using their long snouts
Main gallery through the wood. to chew at the bark.
dug by
mother
beetle
Bark beetle galleries

PASSENGERS AND PARASITES
Trees often play host to smaller
plants, most of which do no harm
to them. Mosses, lichens, and ferns
are common on trees in temperate
regions; in the tropics they are
joined by much flashier plants
such as orchids and bromeliads.
More threatening is the mistletoe:
its sticky seed, which is scraped off
a bird’s beak onto the host tree’s
bark, produces a root that grows
into the living wood. The parasitic
mistletoe then extracts nutritious
sap from the tree. Because most of
its food comes from the tree, the

mistletoe has little need of its
leaves, which are small and
leathery to the touch.

(c) 2011 Dorling Kind2er1sley. All Rights Reserved.

Bark-the outer skin Bark from an ash
sapling

RUBBER TAPPING A tree’s bark is its skin. It protects the tree
Most of the world’s rubber is
made from white latex from attack by animals and fungi, from drying
collected from cuts made in out, and even, in eucalyptuses and redwoods,
the bark of certain trees orig­ from being damaged by forest fires. Just like
inally found in the Amazon skin, bark is made up of two layers. The inner
basin in South America. layer, called the bark cambium, consists of
living cells that are constantly dividing.
Produced in their millions, these cells die when
they are cut off from the supply of water and
sap. But when dead they become the outer
bark and form a highly effective barrier

against the elements.

Bark cambium HOW BARK AGES
The bark of an ash
Old cracked sapling is smooth. As
bark the tree matures, the
New bark develops many
bark cracks and fissures.

Young tree Mature tree HOW BARK GROWS Bark from
Natural cork Every year, the bark a 60-year-
cambium produces a
oak bark new layer of bark old ash
which pushes the
previous year’s bark
outward. The oldest
bark is at the outside.

Cork tile

THICK AND THIN SKINS Bottle corks
Bark varies enormously
in thickness. The bark
of redwoods, like that
of the sequoia on the
opposite page, can be
over 1 ft (30 cm)
thick. By contrast,
the bark of a
mature beech
tree, shown here, may
be as little as 0.5 in
(1 cm) thick over most
of the trunk.

DOUBLE DEFENsE STRIPPING CORK
Old bark, like this from Cork is the bark of the cork
a poplar, forms a double oak. Every eight or ten years,
barrier - it is tough and the outer bark of the trunk is
it contains chemical stripped away to leave the
defenses. Some of these bark cambium. This layer
chemicals are used by then grows into new bark.
people: the Peruvian
cinchona tree, for (c) 2011 Dorling Kindersley. All Rights Reserved.
example, provides 22
quinine, used for
treating malaria.

THE PAST PRESERVED RESISTING DECAY IRREGULAR CRACKING MAPLE SYRUP
Because it has a distinctive pattern, The papery bark of below The early settlers in America
bark, like pollen, can be used to birches is very durable. This strip of horse were quick to take advantage of
identify trees from the past. This As a result, bark from chestnut bark comes the sugar maple - a source of
piece of hazel bark is about 4,000 the North American from a tree about 100 delicious syrup. To make the
years old. The tree that produced it paper birch was once years old. Like the ash, syrup, sap is first collected by
grew near a marshy area, and after used by Indians for the horse chestnut has pushing a hollow tube through
it died it was covered by peat. Acids making canoes. bark that is smooth in a the dead bark to the sap­
in the peat, and the lack of oxygen, young tree, but which conducting layer. The sap is boiled
kept it from decaying. cracks as the tree ages. until only the sticky syrup remains.
It splits into small,
PERFUMED BARK irregular plates as
The spice cinnamon is growth forces
made from the bark of the bark
outward.
a tree that grows in
India and Sri Lanka.
Sticks of cinnamon are
produced by cutting
bark off young saplings;
when left to dry, the

bark curls up.

Deep crack TRAPPED IN TIME THE FIREFIGHTER
Ivy This wasp and a fly The bark of the sequoia is thick and
became stuck in pine fibrous, and because it lacks resin, it
resin oozing from bark does not easily catch fire. These two
50 million years ago. characteristics help to protect the
Fossilized resin like this huge tree from the forest blazes that
is known as amber. kill so many other conifers.
BREATHING THROUGH BARK FLAKING BARK
All plants need oxygen and carbon Many conifers, including the yews,
dioxide, and they “breathe” through spruces, and pines, have bark that
their stems as well as their leaves. flakes off in small pieces as the tree
This cherry wood shows the grows. On this yew trunk, patches of
enlarged pores, or lenticels, which darker old bark have fallen away to
allow gases to penetrate through to reveal light red bark underneath.
the wood beneath.

Lenticel through
which the tree
“breathes”

(c) 2011 Dorling Kindersley. All Rights Reserved.

From bud to leaf

For any plant, growth is a demanding business. Even in trop­ Leading bud
with scales
ical rain forests, where the climate is ideal for growth all year partly folded
round, very few trees can grow nonstop. In higher latitudes,
growth is stopped every year by the cold and darkness of back as it
winter, and resumes as buds burst in spring. Winter buds begins to
Horse chestnut contain the materials that a tree needs to grow quickly once burst
buds spring is under way. They can be found on all deciduous broad­
leaved trees, and on many conifers as well, although conifer buds are less easy Paired
to see among evergreen foliage. Each tree’s buds follow a different plan. In lateral
some trees, the buds contain all the cells needed for the following season’s buds
growth; in others, they contain just the foundations for the following Leaf scar
year, with the cells dividing rapidly once the buds have burst. Trees can be
identified, even in winter, by the shape and arrangement of the buds.

Immature ONE YEAR AGO
leaves Last year’s
growth extends
Bud scales from the leading
bud back to the
THE HORSE CHESTNUT INSIDE A Immature girdle scar. The
Each of the horse chestnut’s BUD stem length of twig
large, sticky buds contains the A bud between these
tightly packed material for an entire contains points shows that it
season’s growth. When the days immature leaves folded was a good year for
lengthen in early spring, the inside a protective case. growth.
resinous coating on the bud melts, Although trees with large
and the protective scales spring leaves often have large buds,
back. The cells within the bud this is not always so.
expand rapidly. Within the space of
two weeks, the shoot can grow by One-year-old side Dormant (inactive)
as much as 18 in (45 cm). The shoot formed from buds begin to grow
leading buds - the ones at the tip of lateral bud at tip only if the
a shoot - contain tightly packed of twig growing buds
flowers as well as leaves. The lateral are damaged
buds (ones on the sides of the Girdle scar shows
branches) contain only leaves. where one season’s
When they emerge from the bud, growth ended and the
horse chestnut flowers and leaves next began
are covered in a protective down.

Three-year-old side TWO YEARS AGO
shoot formed from The twig did not grow
lateral bud at tip very long and did not
of twig produce any side shoots.

Girdle
scar

THREE YEARS AGO “WITCH’S BROOMS”
During this year, the Uncontrolled growth of buds
twig did not grow a great may be set off by infections;
deal. The twig produced a this is often seen in birches.
side shoot which is now
three years old.

(c) 2011 Dorling Kindersley. All Rights Reserved.
24

Buds arranged
alternately
on stem

Single fur-clad scale PREPACKED Pear in blossom BUDS WITH WHISKERS
surrounding bud FLOWERS Single bud at tip of These whiskers are
FUR-CLAD Some fruit trees each twig characteristic of the
BUDS begin to Turkey oak, a species
Of all the trees flower before now found throughout
found in parks and gardens, they come into Europe but once
magnolias are among the easiest to leaf. Each bud confined to the Buds
identify in winter. They can be contains a tightly Near East. Like all arranged
either deciduous or evergreen. In packed flower cluster oaks, it has a alternately,
deciduous magnolias, each winter that opens before the cluster of buds except at
bud is covered by thick “fur.” The new season’s shoot has at the ends tip of twig
buds open in early spring to reveal developed.
broad oval leaves and large waxy of its twigs.
flowers (p. 34). Flower buds may be
1 in (2.5 cm) long.

Leading bud

Axillary bud Whiskers
produces wind­ surrounding bud
pollinated
OPPOSITE BUDS flowers before ALTERNATE BUDS Beech buds burst to
The buds of trees such leaves develop Poplar, birch, plane, and beech buds reveal leaves that
as ashes and maples Paired black are arranged alternately on the open like fans
are opposite - in other buds typical twigs. Beeches are renowned for the
words, in pairs on of ash depth of shade that they cast - the
either side of the stem. arrangement of their buds ensures
On an ash branch, the that each leaf receives
male and female the maximum amount
flowers are produced of sunlight.
by the smaller axillary
buds which lie just
behind the leading
bud. The leading
bud itself produces
only leaves.

Buds arranged Beech mast (p. 40) and leaves Wayfaring tree
alternately, leaves and
rather than flowers
in pairs

Growth occurs in Buds farther away
any direction from tip of twig are
arranged alternately
Cluster of buds
at tip of twig

CLUSTERED BUDS UNPROTECTED
Oaks have buds that BUDS
are arranged in clusters Most trees clothe their
at the tip of each twig. buds with thick scales,
Because growth can but some, like the
proceed in almost any wayfaring tree, have
direction, this buds without this sort
clustering gives oak of protection. The
trees their characteristic wayfaring tree makes
spreading appearance. up for its lack of scales
This is particularly true with a fine covering of
of the English oak, hair on the
shown here. undeveloped leaves.

(c) 2011 Dorling Kindersley. All Rights Reserved.
25

Simple leaves Veins spread out Microscopic pores
across the leaf on surface of leaf
The leaves of a tree are like miniature blade in a network allow gases to enter
Stalk or
power stations, but instead of burning petiole Leaf blade
fuel, they generate it. They take in energy
in the form of sunlight and use it to turn carbon dioxide Midrib
and water into sugars. These sugars can then be used as Close-up of a
a fuel, or they can make cellulose, the substance that simple broadleaf
forms the tree’s cells and on which the wood-forming
substance, lignin, is laid down. The leaves of broad­
leaved trees can be divided into two types -
simple and compound (p. 28).

White willow Jagged teeth
Osier around edge
of leaf

Upper surface,
covered in
fine hairs

LANCE-LEAVED WILLOWS TOOTHED OVAL LEAVES YOUNG GIANT
Many willows have The shape of the The oval leaves of some
long narrow leaves cultivated cherry leaf is magnolias can grow up to
with silvery hairs on common to many trees. 1 ft (30 cm) long. This
the undersides. specimen is a young leaf.

Smooth, dark Underside SAW-TOOTHED
upper surface CHESTNUTS
The sweet chestnut’s jagged, tough
leaves are a familiar sight in
Europe. The same distinctive leaves
were once well known in North

America until chestnut
blight destroyed all
the trees.

HEART-SHAPED LEAVES
Symmetrical (even)
heart-shaped leaves are SOFT UNDERSIDES
uncommon in the tree UNEQUAL LOBES The round leaves of the Copper beech
world: the redbud and Leaves with unequal gray poplar have pale, descended
the katsura are two lobes are grown by downy undersides. from a natural
basswoods. In summer they may mutation
garden species that have become covered with honeydew
them. This leaf is from produced by sap-sucking insects.
the redbud.
Normal
holly
VARIEGATED LEAVES
Variegated Variegated In most leaves the Cultivated UNUSUAL Cultivated
holly holly green pigment Japanese PIGMENTS Japanese
maple Dark-colored leaves maple
chlorophyll, which contain the green
harnesses the energy pigment chlorophyll, but
of sunlight, is spread it is masked by various
throughout the leaf. other pigments.
In a variegated
(multicolored) leaf, it is
reduced or absent in
parts. These leaves
cannot trap much sun­
light and rarely survive.

(c) 2011 Dorling Kindersley. All Rights Reserved.
26

Young leaf emerging
from sheath on
growing shoot

Central notch English oak
divides leaf VARIABLE SHAPES
in two Most deciduous oaks have lobed
or toothed leaves, which are
Two-pointed Parallel Red usually leathery to the touch. White
leaf veins oak Evergreen oaks are quite different - oak
ODD TREE OUT many of them have short, lance­
The two species of tulip tree - one shaped leaves.
North American and the other
Chinese - have large, flat-ended ANCIENT SURVIVOR Vine-leaved
leaves that are quite unlike those of The primitive ginkgo’s Japanese maple
any other tree. The specimen shown fanlike leaves have
here is a young leaf with two points. remained unchanged
Large mature leaves usually have
four points (p. 37), which can be for over 200 million
arranged in a variety of ways. years. Once known

only in China, this HANDLIKE Japanese maple
tree is now grown LEAVES
in parks and Maple leaves are
gardens all over generally easy to
the world. recognize by their
Snake-bark handlike shapes.
maple However, some species,
such as the snake-bark or
moose-bark maples of China, Japan
and North America, can be confusing
at first: many have scarcely lobed
leaves. The leaves of another maple,
box elder, are compound (pp. 28-29).

LATE INTO LEAF CITY DWELLERS
Catalpas, or Indian Although plane leaves are hand­
bean trees, have some shaped, planes are not related to
of the largest of all
simple deciduous maples, as their fruits (p. 41)
leaves, reaching 1 ft clearly show. Plane leaves have
(30  cm) in length.
Catalapas are natives of a tough, glossy surface that
the subtropics. When is washed clean by rain,
they are grown in helping them to grow well
cooler climates the
leaves do not reach full even in the polluted
size until midsummer. air of cities.

Mature catalpa

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27

Compound leaves PEA-FAMILY LEAVES TOOTHED LEAVES
Rounded, paired The rowan, or
Compound leaves include some leaflets are often a mountain ash, with
clear sign that a tree its feathery leaves will
of the biggest leaves found on broad­ belongs to the pea grow anywhere, from
leaved trees. They can measure 3 ft family. This group urban streets to rocky
(1 m) from stalk to tip, so big that at includes the acacias hillsides.
first sight they look like collections of separate and the North
leaves attached to one stalk. But a closer look American black
shows that this is not so: compound leaves each locust, shown here.
grow from a single bud, and when autumn
comes many of them fall off in one piece, each
leaving a large leaf scar where they
were attached to the tree.

ODD-NUMBERED LEAFLETS
Compound leaves with three
leaflets are fairly rare.
The trees that have them
include some maples and
the common hoptree. The
European laburnum is grown
for its yellow flowers.

Laburnum leaf Leaflets almost
Leaflets larger toward equal sized
end of leaf

Mature hickory

HICKORIES AND WALNUTS SLENDER LEAFLETS
The hickories, walnuts, and The staghorn sumac’s elegant leaves
wing-nuts make up a are a familiar sight on
distinctive family of trees. All unused land in the
have large compound leaves United States and
that can be up to 30 in (75 cm) long. This leaf is in gardens in Europe. The forked
from a bitternut, one of the hickory species found in stems of this shrubby tree are covered
the extensive forests of the eastern United States. in dense fur, making them look like the
antlers of deer before their velvety
skin has been shed.

(c) 2011 Dorling Kinders2le8y. All Rights Reserved.

Horse chestnut leaf Leaflets arranged
Mature ash tree in leaf in a circle

SHORT-STAY LEAVES PALMATE LEAVES
In Europe, the commonest large tree with The leaves of all the horse
compound leaves is the ash. Though large, ash chestnut family have leaflets that
leaves are sparse, and even a big ash tree casts little point outward like the fingers of a
shade. In the autumn the ash is slow to shed its hand. The horse chestnut has
foliage. According to folklore the ash tree seven or nine leaflets, while its
possessed medicinal powers, and it was believed relatives, the North American
that a sick child would be cured if he or she was buckeyes, usually have five.
passed through the branches of the ash.

Leaflets paired and Hercules-club
of equal size DOUBLY DIVIDED
The Hercules-club from

North America
has enormous
leaves that are
twice compound:
each leaflet is
attached to a side
stalk. The leaves may
be over 3 ft (1 m)
long and almost as
wide. Doubly divided
leaves are very unusual
among trees. Only one
other tree with them,
also from North
America, is at all
common. This is the
Kentucky coffee tree -
not a relative of the
true coffee bush but a
member of the pea
family. Its seeds were
used as a coffee
substitute during the
last century.

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29

Needles and scales

The needles and scales of conifers are quite unlike the

leaves of broadleaved trees. They have parallel veins and a hard
or leathery surface. With a few exceptions, such as larches, they
remain on the tree all the year round. Including the yews, there
are seven families of conifers, and the most important are the pines,
redwoods, and cypresses. Pine-family conifers include not only
pines but also firs, spruces, cedars, and larches. Conifers
have a variety of leaf shapes. Pines, cedars, and larches,
for example, have needles; firs, yews, and some
redwoods have flattened, leathery leaves;
and cypresses have scales.

Blue atlas Needles ORNAMENTAL CONIFERS
cedar in pairs Many species of conifers have
been bred for their ornamental
Blue-green foliage, which can be green,
needles of yellow, or even blue. These
cultivated feathery scales are from a
blue atlas cultivated sawara cypress.
cedar

NEEDLES IN ROSETTES Scotch pine
A number of conifers are
known as cedars - but Needles Needles
not all are true cedars. in threes in fives
Evergreen needles Arolla pine
that grow in NEEDLES IN BUNCHES
rosettes identify Pines all have long needles that grow in
this group. bunches of two, three, or five. Each needle
has a thick outer layer, or cuticle, and a
Flat, dark coating of wax. Together, these reduce water
green needles loss and allow pines to live in places that are
too dry for many other conifers.

Monterey pine

GRAVEYARD LEAVES FOR ALL SEASONS Underside Upper side
SENTINEL Firs have tough, flat of silver fir of silver fir
The yew’s dark foliage is leaves. Like many other
poisonous. Often conifers, they are Many fir leaves are
planted in churchyards, adapted to cope with differently colored
yews have become a heavy falls of snow. above and below
symbol of death. Their sloping
branches and
smooth, flexible leaves
shed snow easily
without breaking under
its weight. The leaves
have a built-in
“antifreeze” and are not
damaged by frost.

(c) 2011 Dorling Kinders3le0y. All Rights Reserved.

New Hard,
needles triangular
leaves with
spiked tips

Old needles Monkey
puzzle

THE COPPICING CONIFER NEEDLES ON PEGS SCALES AROUND THE STEM UNIQUE
The California redwood or sequoia Spruces have spiky The Japanese cedar has small APPEARANCE
produces sprouts from its stump after needles that grow from scalelike leaves around its The monkey puzzle is almost
felling, just as in a coppiced small “pegs” on their stems. Despite its name, it is a impossible to mistake. Also known as
broadleaved tree (p. 61). twigs. Christmas trees redwood, not a cedar. the Chile pine, it is actually not a pine
are usually Norway but one of an unusual family of
spruces; when they lose conifers found mainly in South
their needles, the leaf America and Australia. It is grown as
pegs are easy to see. an ornamental tree in many parts of
Europe and North America.

Young leaves Soft, flexible
in spring needles are
shed every
autumn

Bald Flattened
cypress scalelike
leaves typical
of the cypress
family

BURSTING INTO LEAF THE DECIDUOUS CONIFER SCENTED LEAVES
The bald cypress (p. 18) is a deciduous Larches (a family that includes the Thujas are members of the cypress family. The
redwood, like its distant cousin the dawn tamarack) can grow in the coldest western red cedar is a thuja. It is easy to identify
redwood (below). Bald cypress leaves are climates. Their needles are in rosettes because when its leaves are crushed, they smell
yellowish when they emerge in spring but and are shed in autumn. like pineapple. Many other conifers have scented
become dark green as they mature. leaves; giant fir, for example, smells like oranges.

A CONTRAST IN SCALE OUT OF THE EAST TWO TYPES OF LEAVES
Although the giant The dawn redwood’s feathery Some junipers
sequoia is one of the foliage is also known from
world’s biggest trees, it fossils millions of years old. have spiky leaves
has some of the It was thought to be when young
smallest leaves. Its tiny extinct until and scalelike
scales are packed tightly discovered growing
around the stems. in a remote part of leaves when
China in adult. The common
the 1940s. juniper, shown here,
Soft, flat needles has only spiky leaves.
are shed every Cultivated junipers
autumn have leaves that are
all shades of green,
yellow, and blue.

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31

Blowing in the wind Female “flower”

Tree flowers grow in a huge range Leaves
sprouting
of sizes and shapes. Some palms have
massive flower heads more than 33 ft EXPOSED TO THE WIND Male “flower”
(10 m) across, while many equally All coniferous trees are wind
large trees have tiny flowers that are pollinated. In the Lawson cypress, FLOWERS
hard to see without a magnifying tiny male “flowers” develop at the tips FIRST
glass. All broadleaved trees produce of the branchlets - the best place for Larches shed
true flowers; conifers grow simpler pollen to be shed if it is to catch the wind their pollen in
structures that are not flowers in the strict and be carried away. early spring,
sense of the word. Many trees rely on before their
the wind to transfer male reproductive leaves develop.
cells, or pollen, to the female cells. As in all conifers,
it is the female
“flowers” that
develop into
woody cones
containing the
seeds (p. 44).

Male “flowers” Male “flowers” Individual male
on underside (catkin) flower within
of twig catkin

SEPARATE SEXES THE EARLY FLOWERING HAZEL Sticky stigma Anther
The yew is dioecious, meaning that male The hazel is one of the first wind­ traps pollen HAZEL CATKIN
and female “flowers” grow on different pollinated trees to come into flower floating in air Catkins form in the
trees. The “flowers” shown here are from in the spring. If the temperature Female autumn but do not open
a male tree. They develop on the stays above freezing for just two or hazel until the following
undersides of its twigs in small clusters. three days in a row, the catkins expand flowers spring. Each catkin
to release their pollen into the chilly air. produces over two
million pollen grains.

Female SEXES TOGETHER Male flowers
flowers The alder is (catkin)
monoecious, meaning
Male Young that male and female
flowers leaf flowers grow on the
(catkin) same tree. The
female flowers
develop in short,
woody catkins.

THE WOODLAND HORNBEAM WIND BLOWN POLLEN
The hornbeam is a tree of deep In dry weather, alder
woodland. Its flowers appear just as catkins shed millions
the leaves are beginning to sprout. of pollen grains into
the air. Each tiny
grain is little more
than 0.03 mm across.

(c) 2011 Dorling Kinders3le2y. All Rights Reserved.

Growing shoot CLUES FROM THE PAST
Pollen grains are very
Cluster of resilient. Scientists can
male discover what trees grew
“flowers “ where from pollen
preserved in peat
deposits.

Cluster of
female flowers

POLLEN IN THE STREETS POLLEN WITH SAILS Cluster of
Ornamental plane trees shed huge Pines produce enormous male Scotch
quantities of pollen into towns and numbers of pollen grains, and if pine “flowers”
cities in spring. Both the male and the male “flowers” are given a sharp BEDRAGGLED CATKINS
female flower clusters are ball­ knock, a cloud of yellow pollen appears. The unimpressive,
shaped, and they hang from Pine pollen grains have two tiny air-filled straggly catkins of the
the tree in small groups. sacs attached to them, and these act like sails to English oak open in
carry the grains far through the air. late spring in untidy
bunches. The
female flowers,
destined to produce the
acorns, are clustered at
the tips of the shoots.

Catkin divided Female flowers
into three on stalks, a
branches characteristic
feature of
English oak Catkin

BRANCHED CATKINS Stigma of NEW AND OLD GROWTH
Hickories shed their female flower The walnut’s catkins sprout from
pollen in early summer
from catkins that are the previous year’s shoot. The
branched into three. The female much smaller female
flowers, which are at the tips of the flowers, whose sticky
shoots, are not at all noticeable. stigmas can be seen
here, develop at
the end of the
new shoot.

(c) 2011 Dorling Kind3er3sley. All Rights Reserved.

Insect-pollinated flowers ATTRACTING BY SCENT

By far the most noticeable tree flowers are The bird cherry
attracts insects not only
by color but by smell.
Like many insect­
those that are pollinated by animals, usually pollinated plants, the
insects. Insect-pollinated flowers have evolved flowers produce
supplies of sugar-rich nectar which draw bees, Stigma an almond­
butterflies, beetles, flies, and countless other insects to them. The (female) like perfume.
pollen grains of these trees are bigger than those of wind­
pollinated flowers - up to .012 in (0.3 mm) across. They Anther (male)

also have a sticky coating that makes them cling
to an insect’s body so that they can be trans­
ferred from one tree to another. Insects transfer
pollen from male
anthers to the female Ovule (female)
ovule via the stigma

Flower made up of
fleshy scales

After pollination,
flowers droop - this
clears a path for bees
toward unpollinated
flowers

AN ANCIENT LINEAGE KANZAN CHERRY
The first flowers to appear on Earth The Kanzan Japanese
belonged to magnolia-like plants, and cherry is one of the most
their cuplike blooms have probably popular varieties in
changed little in 200 million years. cultivation. Huge clus­
The petals are set in a spiral around a ters of flowers weigh
central point containing the male down its branches in
anthers and female stigma. spring, but this variety
A WEALTH OF BREEDING never produces fruit.
Over the centuries, a handful of The elaborate flowers
species of wild cherry have have been so highly
been bred to produce hun­ bred for decoration
dreds of ornamental that their repro­
varieties. Japanese ductive structures
flowering cherries no longer work.
probably came from
four wild Double ring of
species. petals found only
in cultivated
varieties

Anthers and
stigma
reduced
in size

Double ring
of petals

(c) 2011 Dorling Kindersley. All Rights Reserved.

ORNAMENTAL APPLE Ring of ONE SEX AT A TIME
Apples have been cultivated five petals The blackthorn, or sloe, is a shrub
since Roman times not only for or small tree that flowers
their fruit (p. 39) but also for Encrusting lichen before it comes into leaf.
their flowers. Like all As in many flowers, the
apples, the delicate stigma matures before
flowers of this ornamental the anthers release
crab have five petals that sit their sticky pollen.
on a cup known as a receptacle. This keeps the
After the flower has been flower from
pollinated by visiting insects, the pollinating itself.
receptacle swells to produce the Clusters of flowers
outer flesh of the fruit. on spiny side branches

ALL MIXED UP
The horse chestnut is pollinated by
bees. Each flower head is made up
of a mixture of flower types: some
are entirely male, and others

have both male and female
parts. Only the second type
can produce “conkers.”

Ripe anthers
covered in
pollen

MIXED ORCHARDS
The flowers of most
apple varieties will
produce fruit only if
they receive pollen
from a different
variety. By planting
rows of different
varieties together,
apple growers are able
to ensure that bees
carry pollen from one
variety to another.

(c) 2011 Dorling Kindersley. All Rights Reserved.

Animal-pollinated flowers SPRING-LOADED Each flower has
FLOWERS five petals; the
The flowers of many trees are specially adapted to lure lowest pair forms
The flowers of the a projecting
animal visitors. These animals distribute pollen in return redbud are arranged “keel” that
for a meal of nectar, a sugary liquid produced by the springs open
flower. The flowers attract their pollinators by so that the weight of when an insect
their color and scent, and they are shaped so that a visiting insect lands on it
the animal cannot avoid being dusted with pollen. makes them
Although insects are the most important of these spring open. Cultivated
This ensures that hawthorn
pollinators, in some pollen sticks to with double
areas birds and bats also the insect and is ring of
carry pollen and so help carried off. petals
to produce seeds.
Judas tree
TINY in flower
FLOWERS
Maples have
clusters of nectar-rich
flowers that appear
before the leaves or at the
same time. Each tiny flower
has a ring of pollen-producing stamens. This
flower cluster is from a sycamore, a kind of maple.

Wild
hawthorn

LANDING PLATFORM
Small flowers packed
closely together, like
those of the rowan,
provide insects with a
convenient landing platform.

BLAZE OF COLOR
Hawthorns produce
heavily scented flowers.
According to legend, one hawthorn,
the Glastonbury thorn, was brought to
England by St. Joseph of Aramathea. It is
unusual in that it flowers twice a year.

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36

Bract Flower beginning
to open with sepals
folding back

Flower bud

Flower Showy petals at Tube leading
FALSE PETALS mouth of flower to nectar
In most flowers it is the petals that
are large and noticeable and so NAMED FOR Circle of
attract pollinators. But some iTS SHAPE six petals
flowers have evolved other ways of The tulip tree is related to the Sepals folded
getting attention. This flower is magnolias (p. 34). It gets its name back
from a North American dogwood. from its cup-shaped flowers,
The four structures that look like which, like those of magnolias,
petals are in fact special leaves are large and have a central spire.
called bracts which attract insects
to the tiny flower.

Upper and lower half
of beak form a narrow
tube for drinking nectar

BIRD POLLINATION TUBULAR FLOWERS
In the Americas, hummingbirds The flowers of the catalpa, or
pollinate many species of plants, Indian bean tree, are shaped so
including some trees. The birds’ that a visiting insect has to crawl
long beaks reach deep into the deep inside a tube to reach the
flowers to obtain nectar. nectar. In doing so, it is
Hairs at tip of dusted with pollen.
tongue form a
brush to collect
pollen

BAT POLLINATION INSECT LURE
Bat-pollinated trees include the Elder flowers have a powerful
baobab and kapok (p. 43). Both of smell that insects, especially
these trees have big flowers that hover flies, find highly
produce large quantities of nectar, attractive. This perfume can be
especially at night. Bats eat both noticed in elder flower wine,
pollen and nectar, and in doing so which is made by collecting the
transfer pollen from one flower to flowers as soon as they open and
another on their tongues and noses. before their smell becomes sour.
Most tree-pollinating bats hover in
front of the flowers; they use the
same technique as hummingbirds
but are much less acrobatic.

(c) 2011 Dorling Kindersley. All Rights Reserved.
37

Fruit and berries

After a tree’s flowers have been polli-
nated, the female part of the flower pro-
duces the seeds. Trees are faced with the same
problem in scattering their seeds as in scattering
their pollen: the trees themselves cannot
move, so they need the help of something
that can. To get around this problem, many
produce brightly colored, tasty fruit that
attracts animals, particularly birds. In return
FORBIDDEN FRUIT for a meal, a bird will unknowingly scatter seeds
Fruit has often been far and wide in its droppings as it flies from tree
associated with to tree. New trees spring
temptation. Although up where the
the fruit that caused seeds fall.
Adam and Eve’s fall is Small seed
often said to be an surrounded
apple, the Bible just
refers to it as a fruit.

by a fleshy
jacket, known
as an aril

CHEMICAL POISONOUS
COLORS FRUIT
Red berries, like Yews, like junipers,
those of the rowan, are conifers, but
are colored by carotenoids. These they are
get their name because they also
color carrots orange. unusual in
producing juicy,
Ripening MIDSUMMER MULBERRY colored “berries”
black Greek legend has it that the mulberry’s fruit like those of
broadleaved trees.
mulberry was stained red by the blood When a bird feeds on
of Pyramus, the lover the bright red fruit, the
who also appears in fleshy aril is digested but the seed,
Shakespeare’s A Mid­ which is poisonous, passes
summer Night’s Dream. through its body intact.

Ripe black
mulberry

Silkworm caterpillars
feed only on white
mulberry leaves

MIDWINTER FOOD Mulberries THE
Hawthorn berries are a vital food for birds in hanging TENACIOUS ELDER
winter. They remain on the tree long after most down beneath Elderberries are often eaten by
other hedgerow berries have disappeared. leaves birds. The seeds that fall in their
droppings can germinate and grow
with almost no soil. They are often
seen growing out of houses, where a
seed has germinated in a wall.

(c) 2011 Dorling Kindersley. All Rights Reserved.
38

Cultivated fruit The “russet” Fleshy layer SCIENCE AND THE APPLE
– an old, develops around Apple breeders, or pomologists, use
Since tree seeds were first established variety the base of the the science of genetics to produce
deliberately planted, with a thick, rough pollinated flower
gardeners have spent skin Seeds apples that taste good and that are
centuries improving and Single, hard stone easy to pick. Modern apple
adapting fruit to human needs typical of plum fruit trees can be cropped when
by selective breeding. The apple they are saplings only a
is a good example of the yard or so high.
changes that cultivation has The “Worcester
made. Wild apples, which are pearmain” - a modern
still found in woods and variety
shrublands, are small and
bitter and relished by birds but Pear
not by humans. Over a
thousand cultivated varieties
have been produced, all much
larger and sweeter than their
wild counterparts. This has
been achieved by continually
selecting seeds from the most
promising trees, and by
crossing one tree with
another in the hope of
combining the best of their
characteristics.

Seed Boundary of
Nectarine seed compartment

FROM STONE TO FRUIT OUT OF THE WILD FAMILY LIKENESS DIVIDED UP
Like all plums, damsons Most cultivated plums are The plums include not Inside the fruit the seed
are easy to grow from the descendants of two only true plums but compartment of apples and pears
their stones. These are wild shrubs, the also cherries, peaches, is divided into sections, each
some of the smallest blackthorn, or sloe (p. 35), apricots, nectarines, containing one or two seeds.
cultivated plums. and the cherry plum. and almonds.
Seed compartments visible THE CITRUS FRUITS
at flat end of fruit Citrus fruits like oranges and
lemons contain fruit sugars
and citric acid. In lemons, the

acid outweighs the
sugars, giving the
fruit a sharp
flavor.

SWEET AND SOUR
Oranges originally
came from Asia. The
sweet orange, used for eating, and the
Seville or sour orange, used for
marmalade, are two different species.

STAPLE DIET
Thrushes, blackbirds, and

many other birds rely on
berries to survive
the winter.

THE MEDLAR THE ANCIENT OLIVE
Like the apple, the seed compartment of the Botanically speaking,
medlar is divided up into five sections. Medlars the olive is a fruit. It
are usually eaten only when they begin to rot. has been cultivated for
its rich oil for
thousands of years.

(c) 2011 Dorling Kindersley. All Rights Reserved.
39

Seeds and nuts

Trees disperse their seeds in a number of ways: some SEED CATKINS
In late summer, wing­
wrap them up in berries that are tempting to birds (p. 38); nut trees, which come
others produce seeds inside tough cases. The seeds, from Asia and Japan,
together with their cases, make up the trees’ fruit. The exact are covered in giant
catkins hanging down
from their branches.
shape of the seedcase depends on how the seed is dispersed - These are in fact long
whether by mammals, wind, or water. Some trees, such as clusters in cases with
walnuts and beeches, produce big, well-protected seeds. These are flaps. The short
carried away by hungry mammals such as squirrels, and although flaps probably
some seeds are eaten, a number survive and germinate. Other trees help to dislodge
the seeds once ripe.

have seeds inside winged cases that are carried by the wind. A few
riverside trees, such as the alder, use water to disperse their seeds.
The case of an alder seed contains a droplet of oil that makes it
float, so the seed is swept away downstream by the current to
germinate when it arrives on
a muddy bank. Filberts
BEECH BANQUET
Once a year, beech trees
produce mast, or beech­
nuts. In the past, pigs
were often turned loose
beneath beech trees
to fatten on the oil-rich
seeds.
COBS AND FILBERTS
Cultivated hazelnuts
SEEDS ON THREADS are sold as “cobnuts.”
The seeds of the Filberts, which are
cucumber tree, a type larger, come from a
of magnolia, show up hazel that grows in
as round swellings in a southeastern Europe.
bright red pod. Each
swelling splits open to
reveal a brilliant red
seed suspended on a
silk-like
thread.

SMALL NUTS
Pistachios come
from a small Asian tree that
is now grown around the
Mediterranean and in the
southern United States.

Prickly case protects
developing nuts

Horse chestnut
cases are
usually
spiny

Roasting chestnuts WINTER WARMER SHINY “CONKERS”
Roasted sweet chestnuts Horse chestnuts, or “conkers,” are slightly
are tasty and nutritious. poisonous to humans. Other mammals,
The best nuts grow in especially deer, cattle, and sheep, can eat
warm climates, such as large quantities of them without
in Spain and California. suffering any ill effects.

(c) 2011 Dorling Kindersley. All Rights Reserved.
40

Single wing attached Seeds are scattered Ash keys often
to each seed as pods split open remain on tree
throughout the
winter

Winged cases
hang in pairs

WINGED MAPLE SEEDS POISONOUS SEEDS FLYING KEYS
Maples have seeds in winged The laburnum tree, often grown in Completely female ash trees produce winged
cases. When the cases fall, they gardens, has highly poisonous “keys” and in some years bear them on all
spiral to the ground like miniature seeds. As in all pea-family trees, branches. However, male trees have no keys. In
helicopters. the seeds grow in pods. trees with both male and female branches, only
the female ones bear keys.

Long clusters FIRST ARRIVAL Unripe
of seeds Each birch seed is seedhead
gradually enclosed in a case with
fall apart two tiny wings. The
during the fruits are light enough
winter to be blown long
distances, so birches
BASSWOOD NUTLETS appear quickly on
Basswood trees have unused ground.
small bunches of
fragrant, yellowish Ripe acorns of
flowers. After these Turkey oak
have been pollinated,
each flower produces a
furry nut containing
the small seeds.

Healthy unripe
acorn

ALDER “CONES” EDIBLE SEEDS Acorn cup “SPORTING” SEEDS
Alder seeds develop Most oaks do not begin deformed into a The tulip tree’s seeds grow
inside the female to produce acorns until they are gall by larva of in a pointed seedhead. At first, the
catkin. This woody about 50 years old. To a botanist, acorns gall wasp cluster is green, but gradually it
catkin looks like a are in fact nuts, but they are not commonly turns brown and opens to look like a
miniature pine cone called nuts because people rarely eat them. shuttlecock. The seedhead falls apart
as it matures, but it However, they used to be the staple food a year after flowering.
is not related. of one tribe of Indians in California who
ground them down into flour.

Skin
surrounding
nut

AMERICAN FAVORITE
The pecan is one of the
most important
edible nuts from
North America. It is
produced by a tree
Edible related to the walnut,
Woody kernel and its nuts taste very
shell similar to walnuts.
HAIRY IRRITANTS
Plane tree seeds grow
in ball-shaped clusters
that stay on the tree all winter. In
THE SQUIRREL’S HIDDEN STORES COLORED SKINS spring they burst open, releasing the
Squirrels eat many seeds and bury On the tree, a walnut is covered by seeds and millions of tiny golden
others to provide food for the a green skin that gradually turns hairs. These hairs can have an eye-
winter. The ones that the squirrels black, collapses, and releases the watering effect on anyone who
haven’t eaten germinate when nut. The walnut is enclosed in a encounters them.
spring arrives. hard shell that keeps out animals.

(c) 2011 Dorling Kindersley. All Rights Reserved.
41

Tropical fruit and nuts

Tropical trees that produce edible fruit TAMARIND PODS
and nuts have been bred by people since The Indian tamarind
ancient times. The date palm, for tree is a member of
example, is known to have been culti­ the pea family (p. 28),
vated for at least 5,000 years. People and, like all its
have also carried countless species from one relatives, it produces
place to another to provide food. Examples seeds in pods. The
include the papaya, avocado pear, and flesh around the seeds
cocoa, which originally grew in South is a valuable spice, and
America, and the mango, which came the pods are also a
from Asia. Perhaps the most famous traditional medicine.
of these tropical travelers is bread­
fruit. During the first attempt to Dried nutmeg
transport it from the South Seas to NUTMEG AND MACE
the West Indies, the crew of the ship The nutmeg tree
The coconut palm - a carrying it, HMS Bounty, mutinied provides two different
tree that spreads by against the notorious Captain Bligh. THE SPICE TRADE spices. The first is
waterborne seeds Many spices produced from tree nutmeg itself, which is
seeds are used to flavor food. the tree’s seed. The
second is mace, an
Hard shell Stalk attaches intensely flavored,
protects the pot to tree fleshy network that
nutritious surrounds the seed.
kernel
Thick wooden
Seeds and case case surrounds
together weigh up nuts
to 3.5 lb (1.5 kg)
Hole closed by plug
BRAZIL NUT
These nuts come from the Amazo- Plug
nian rain forest. The trees on which
they grow have never been
successfully cultivated, so all Brazil
nuts have to be gathered from wild
trees. Collecting Brazil nuts is not
easy. The trees are often very tall,
and the nuts are contained in a
hard wooden case which has to be
smashed open.

Lightweight husk
acts as a float

OCEAN WANDERERS Monkeypot nuts
Many trees that grow MONKEYPOT
on tropical coasts The “monkeypot” tree is a relative of
scatter their seeds by the Brazil nut. It produces its seeds in
dropping them into the wooden cups that Indians once used
sea, where they are for catching wild monkeys.
carried off by currents.
Many eventually sink,
but some do reach land
far away from their
original home and take
root. This seed is from a
tropical tree called
Barringtonia. Its flowers
open at night and
wither at dawn.

(c) 2011 Dorling Kindersley. All Rights Reserved.
42

MEAT TENDERIZER Baobab tree
As well as being very THE SHRINKING TREE

sweet, the papaya (or The extraordinary
papaw) is rich in baobab produces long,

papain, a substance sausage-shaped pods
that breaks down packed with seeds rich in
proteins. Papain
is collected from vitamin C. The baobab
papaya fruit has a huge swollen trunk
and used to
tenderize meat. which is used to store
water. In times of
THE MANGO drought, the tree
Sweet-tasting mango
fruit comes from trees shrinks as this supply of
that originally grew in water is used up.
southeast Asia. They
are now cultivated
throughout the tropics.

Date palms

Coconut germinating after a sea- FRUIT FROM THE DESERT COCOA AND CHOCOLATE
crossing many months long Date palms are native to It was the Aztecs who first
Africa and the Middle East. made a substance they called
The fruit grows in hanging chocolatl, or chocolate, from
clusters, each containing up the seeds inside cocoa pods.
to 1,500 dates.
THE WORLD’S BIGGEST SEED
The coco-de-mer’s enormous nut weighs up to 45 lb
(20 kg), making it the largest seed of any plant.
Coco-de-mer grows only in the Seychelles
islands. Its nuts are divided into two lobes
and for this reason are sometimes called
the “double coconut.”
Hard
seed-
case

Fibers
surrounding

seeds

NATURAL FIBErS
Before the invention
of artificial fibers, the
fibers produced by the
kapok tree were
collected and sold for
stuffing mattresses
and furniture.

(c) 2011 Dorling Kindersley. All Rights Reserved.

Cones Mature Young cones
cone
Mature
Compared with many broad­ Young cone
cones
leaved trees, conifers take a long AGE DIFFERENCES
time to produce their seeds. When the larch’s leaves
Crossbill feeding During the months that the seeds fall away in autumn,
TUFTED CONES greenish young cones
take to develop, they are protected by a hard cone. In The cones of Japanese are visible near the tips
cedar are simple to of the branches and
trees such as the pines, the cone falls off in one piece identify because they older brown cones are
some time after the seeds have been shed. In others, are ball-shaped and farther back.
such as the cedars, the cone falls apart on the tree, so each scale has a
it is hardly ever found whole on the ground. featherlike tuft
projecting from it.

Cones become
hard and
brown when
mature

Young Mature SMALL CONES A SHORT LIFE
Douglas cone The western red cedar, a species of thuja Spruce cones are
fir cones (p. 31), has clusters of tiny cones perched smooth and
THE “FAKE” FIR among its leaves - quite unlike the cones slightly flexible,
True firs have upright of true cedars. unlike hard pine
cones that fall apart cones. They fall
high up on the tree. soon after releasing
The unrelated Douglas their seeds.
fir has hanging cones
that fall to the ground
in one piece.

Young A GIANT’S CONES
cones The giant sequoia has
on small, round cones that
branch take two years to ripen.

Disintegrating
cone

Scale ON SHOW
with Cedar cones
seeds sit upright on
attached the branches.
They take up to
Mature cones OPENING UP EGG-SHAPED CONES three years to
ROUND CONES Cypress cones have The cones of true cedars are smooth mature and a
Cypress cones are small and 6-12 disklike scales and egg-shaped. They consist of a number of years
rounded, and often grow in clusters. that gradually part spiral stack of scales, each of which to disintegrate.
The cones shown here belong to the from each other as has two seeds attached to it. When a
Lawson cypress, which is often the cone matures. cone is mature, the tip breaks up,
found in gardens. When the cones Monterey cypress and very gradually all the scales fall
are young, they are blue-green and cones are unusually to the ground.
tightly closed. large, and their
scales are visible.

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44

Shell Mature cone Mature
surrounding cone
seed kernel
Young cone Scotch
pine seeds
Scale NATIVE PINE
The Scotch pine has
INSIDE A PINE CONE Young green cones small pointed cones.
It takes up to three years for the female pine “flower” to develop into the This species is one of
familiar seed-bearing cone. At first the cone is soft and about the size of a only three conifers
pea but, after pollination, it grows and hardens. During this process it native to Britain, the
changes color from dark green to brown as most of the cells within it others being the yew
become lignified (made woody). Pine seeds develop in pairs, with two seeds and the juniper.
being attached to each scale in the cone. Each seed has a delicate wing,
which is pressed against the scale for protection. In the stone pine, whose
cone is shown here sliced in half, the seeds are large and have a tough shell.
These seeds are the pine kernels that are used in cooking.

Scales open Scales close
in dry weather completely in
wet weather

Scales begin WHITE TIPS
to close when White, or Weymouth,
air becomes pine is one of a number
moister of pines that have long,
cylindrical cones that
A CHANGE IN THE WEATHER? Paired cones of look like spruce cones
Pine cones are traditionally used to cluster pine in outline. The white
forecast the weather - a piece of marks at the tips of the
country lore that does actually scales are spots of resin
contain a grain of truth. As these that oozes from the
cones show, their scales can be open young cone.
or tightly shut. Cones release their
seeds in dry weather; when it is Sugar pine seeds
damp, the scales close up to keep have wings up to
the seeds dry. 1.5 in (4 cm) long

CONES IN CLUSTERS Old cone that CALIFORNIAN GIANT
Cones develop from female “flowers” that has shed most The sugar pine has some of the largest cones
grow in groups on developing shoots. of its seeds of any conifer. The cones are usually about
Because the cones may stay on the trees 15 in (40 cm) long, but in some specimens they
for many years, this can create branches can reach lengths of nearly 2 ft (60 cm). A
that have clusters of cones at regular single cone can weigh as much as 1.1 lb (500 g).
intervals along their length. Many pines Sugar pines are found in the mountain areas
have cones that develop in pairs. of the western United States. They get their
name from the resin they produce, which has
a sweet taste unlike that of most pines.

(c) 2011 Dorling Kindersley. All Rights Reserved.
45

Falling leaves

Leaves get their color from the green pigment they contain CLIMATIC VARIATION
Cherry leaves turn red
called chlorophyll, which harnesses the energy in sunlight. To or yellow, depending on
make the most of the sunlight falling on their leaves, plants often both tree and climate. In
have “accessory” pigments as well. These absorb light of different some years the colors
wavelengths and pass the energy on to the chlorophyll. The main are much stronger than
accessory pigments are carotenoids, which can be orange, yellow, or red; in others.
xanthophylls, which are yellow; and anthocyanins, which are purple, scarlet,
and blue. Before a deciduous tree sheds its leaves, the balance of these
pigments changes, and the result is
often a brilliant burst of color.

BRED FOR COLOR
Some ornamental trees are
grown especially for their
autumn colors. Maples are well
known for their bright autumn
tints, and in the exquisite
Japanese maples, oriental-plant
breeders have attempted to
improve on nature by
emphasizing this feature.

AMERICAN FALL GARDEN GLORY
The eye-catching Persian ironwood has some of the richest autumn
colors of a New colors of all trees found in gardens. The reds,
England autumn oranges, and yellows in its leaves are created by
are produced mainly carotenoid and anthocyanin pigments.
by oaks and Carotenoids get their name from the fact that they
sugar maples. make carrots orange. They also provide the color

of many other vegetables, fruits, and flowers.

Yellow color produced
by a carotenoid pigment

DESIGNED FOR COLORFUL
DISPOSAL RELATIVES
Each year a The more sugars
deciduous tree like that a leaf contains,
the horse chestnut the brighter its autumn colors are likely to be. The
invests a huge amount of sycamore, a European maple, has fairly bright autumn
energy in producing new leaves and then throwing them away. One colors, but they cannot rival the brilliance of
advantage of disposable leaves is that it does not matter too much if American maples. This is because the more extreme
they get damaged. Unlike the evergreen conifers, deciduous trees do American climate helps a tree to produce sugars and,
not need resins or a thick coating of wax to protect their leaves. from them, makes more anthocyanins.

(c) 2011 Dorling Kindersley. All Rights Reserved.
46

Next year’s bud
Leaf stalk
Corky layer

WHY LEAVES FALL
As autumn proceeds, a
layer of cork grows
across the leaf stalk,
eventually causing the
death of the leaf.

PIGMENT
DESTRUCTION
These leaves from a
snake-bark maple
show how the
destruction of
chlorophyll, which
began at the outer edges
of the leaf, is gradually
working inward.

TRANSATLANTIC COLOR SPECTRUM
Most European oaks turn a dull brown in autumn,
while in North America the leaves of some red
oaks turn bright crimson.

Area without Area with
chlorophyll chlorophyll

HOLDING ON
Not all dead leaves are
shed immediately.
Young beeches keep
many of their leaves
until the next spring.

INTERNAL DESTRUCTION WASTE REMOVAL
In this hickory leaflet, the Like animals, plants
chlorophyll is being destroyed not must get rid of toxic
only inward from the leaf edge, but waste products. As well
also outward from the leaf’s midrib. as reabsorbing minerals
from its leaves, a tree also
deposits waste products in them before they
fall. This produces brownish colors, as in this
tulip tree leaf.

CHANGING COLOR
As a leaf dies, the carotenoids in it may
undergo a series of chemical changes in
which they turn from yellow to orange to red.
At the same time, scarlet anthocyanins are
produced from sugars in the leaf.

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47

The death of a tree

PETRIFIED WOOD From the moment they germinate, trees live side by side with the
Most wood soon decays,
but if buried in water­ organisms that will eventually kill them. Insects create small wounds in their
logged conditions or in wood, ivy scrambles up their trunks, and a deadly rain of fungal spores settles
peat it may become on their branches, ready to infect any point of weakness. Bit by bit, the tree
petrified wood, in surrenders parts of itself to its attacker, sealing off rotten branches and
which the wood’s decaying heartwood in an attempt to stay alive.
shape is preserved The battle may be waged for years, but
by minerals. inevitably less and less living wood
remains, until one spring the sap no
longer rises and the tree is dead.

Deer feed on the
bark of saplings,

thereby cutting
off their sap
supply

COMPETING Thick, shiny leaves A LIVING CARPET
FOR LIGHT reduce water loss Once wood rots, it soaks up water
Ivy weakens trees by like a sponge, making it a perfect
reducing the light supply. DOUBLE TRUNKS surface for moisture-loving plants to
As ivy climbs up a tree, it The left of these two grow on. This dead log is covered by
uses tiny rootlets to anchor trunks is actually the ferns and mosses. Like fungi, ferns
itself onto the trunk and branches. stem of an old ivy and mosses grow from spores - tiny
Although the rootlets absorb moisture from plant. cells that are wafted through
the bark, they do not penetrate the wood. the air by the breeze.

DUST TO DUST
When wood decays,
the minerals that it
contains find their way
back into the soil to be
taken up by living trees.
In mature forests,
growth and decay are
finely balanced.

Adult male
stag beetle

ROTTING AWAY FEEDING ON WOOD Stag
Living wood has many chemical defenses The larva of the stag beetle
against attack by fungi, but once wood has died, beetle feeds on
the chemicals gradually break down and are no decaying wood. Wood larva
longer effective. This branch shows the result of lice feed mainly on
five years’ decay on a woodland floor. Wood lice fungi, rotting leaves, Evergreen fronds of
and other dead plant polypody fern
matter.

(c) 2011 Dorling Kindersley. All Rights Reserved.
48

Toadstools IN AT THE KILL CREEPING DEATH SPREADING BY SPORES
growing in dead Many woodland fungi can continue An attack by honey fungus often Fungi spread mainly by
wood to live on the remains of a tree after spells death for a tree. The their spores. Most
THE HIDDEN LIFE OF FUNGI it is dead. These toadstools are fungus spreads by spores and by toadstools produce
Fungi may feed on dead or living wood. Toad­ sprouting from a decaying stump. thick strands, sometimes known spores on gills that
stools, which are produced by certain types of as “bootlaces.” These grow hang vertically from
fungi, appear only when the fungi needs to between a tree’s bark and wood. the toadstool’s cap.
produce spores. The long slender strands HARMLESS GUESTS
through which fungi feed are hidden from Plants that live on trees
sight inside the wood. are divided into two
types. Parasites, like
Wood mistletoe, live on
nutrients “stolen” from
Underside of their tree host.
bracket showing Epiphytes, like these
spore-producing tropical bromeliads, just
pores use a tree as a perch and
do it no harm.

BRACKET FUNGUS INSIDE ATTACK
The many different species of bracket fungus grow on both living and dead The larvae of longhorn
wood. Although they are often slow-growing, they probably kill more tree beetles damage trees by
than any other group of fungi. Unlike most gilled toadstools, the brackets chewing through the
are hard and survive for a number of years. Their spores are usually living wood.
dispersed from round pores.

Moss

(c) 2011 Dorling Kindersley. All Rights Reserved.