Ultimate Visual Dictionary (DK)

ORNITHOPODS 2





EXAMPLES OF HADROSAURS










HYPACROSAURUS HADROSAURUS GRYPOSAURUS
Length: 30 ft (9.1 m) Length: 26–33 ft (7.9–10 m) Length: 26–33 ft (7.9–10 m)


Bony crest
Dorsal Orbit
vertebrae Air passage Infratemporal
Air passage
Cranium fenestra
Infratemporal fenestra
Orbit Naris




Cervical
vertebrae
Mandible Tooth
SKULL AND MANDIBLE
OF JUVENILE
LAMBEOSAURUS

Mandible Naris





Scapula
Bony
Sclerotic ring crest
Shoulder joint
Cranium
Tibia
Rib
Orbit
Humerus
Fibula
Elbow joint Naris
Radius
Wrist joint
Ulna
Infratemporal Mandible
Phalanges Premaxilla
fenestra
Metacarpal
SKULL AND MANDIBLE OF
Phalanges ADULT LAMBEOSAURUS


99

PREHISTORIC EAR TH
Marginocephalians 1 Thick, high-
domed cranium
Supraorbital ridge
MARGINOCEPHALIA Orbit
(“margined heads”) were
Naris
a group of bipedal and quadrupedal
Mandible
ornithischian dinosaurs with a narrow Neural spine
shelf or deep, bony frill at the back of
HEAD-BUTTING PRENOCEPHALES
the skull. Marginocephalians were
probably descended from the same ancestor as the ornithopods and
lived in what are now North America, Africa, Asia, and Europe during
the Cretaceous period (145–65 million years ago). They were divided Cervical
into two groups: Pachycephalosauria (“thick -headed lizards”), such rib
Humerus
as Pachycephalosaurus and Stegoceras, and Ceratopsia (“horned
faces”), such as Triceratops and Psittacosaurus. The thick skulls of Ulna
Pachycephalosauria may have protected their brains during possible Radius Pubis
head-butting contests fought to win territory and mates; their hips Wrist joint
and spines may also have been strengthened to withstand the shock. Metacarpal
The bony frill of Ceratopsia would have added to their frightening
Phalanx
appearance when charging; the neck was strengthened for impact Ilium
and to support the huge head, with its snipping beak and powerful Ischium
slicing toothed jaws. A charging ceratopsian would have been a
Metatarsals
formidable opponent for even the largest predators. Ceratopsians
Phalanges
were among the most abundant herbivorous dinosaurs of the
Late Cretaceous period (97–65 million years ago).
EXAMPLES OF SKULLS OF PACHYCEPHALOSAURS
Thickened dome
Thickened dome
of cranium
Thickened dome Orbit of cranium
Orbit of cranium
Bony spike
Maxilla
Bony
ridge
Bony
Maxilla nodule
Tooth Maxilla Bony
Mandible
SKULL AND MANDIBLE Orbit nodule
OF STEGOCERAS SKULL OF PRENOCEPHALE SKULL OF PACHYCEPHALOSAURUS
EXTERNAL FEATURES OF Bony nodule Thickened dome
PACHYCEPHALOSAURUS Scaly skin of cranium
Domed head
Eye Bony nodule
Bony spike
Neck
Snout
Tail Knee Forelimb
Hind limb Finger
Buccal cavity
Ankle Hand Brain cavity
Claw SECTION THROUGH SKULL OF
Foot PACHYCEPHALOSAURUS
Toe

100

MARGINOCEPHALIANS 1

EXAMPLES OF
PACHYCEPHALOSAURS









HOMALOCEPHALE WANNANOSAURUS PRENOCEPHALE
Group: Pachycephalosauria Group: Pachycephalosauria Group: Pachycephalosauria
Length: 10 ft (3 m) Length: 2 ft (60 cm) Length: 8 ft (2.4 m)

SKELETONS OF STEGOCERAS Caudal vertebrae
Sacral
Orbit
Dorsal vertebrae vertebrae
Cervical
vertebrae
Chevron
Naris
Neural spine
Ilium
Hip joint
Cervical rib
Mandible Prepubis
Radius Femur
Ischium
Rib Scapula
Wrist Knee joint
Ulna joint Elbow Fibula
joint Tibia
Ankle joint

Metatarsals
Domed head
Bony shelf
Claw
Phalanges
EXTERNAL FEATURES OF
Outer ear STEGOCERAS
Eye

Scaly skin
Naris
Neck
Shoulder
Tail

Thigh
Forelimb
Hind limb
Hand
Elbow Knee
Finger Ankle
Claw Toe Foot
Claw

101

PREHISTORIC EAR TH
Brow horn
Marginocephalians 2 Parietosquamosal Nose horn
frill
Epoccipital bone


Thick, scaly
Parietal fenestra Epoccipital bone skin
Parietosquamosal
frill
Thigh
Tail
Nose horn
core
Supraorbital Hind Eye
ridge
Ankle limb
Naris
Orbit Elbow
Naris
Cranium Nail Toothless
beak
EXTERNAL FEATURES Forelimb Wrist
Mandible OF TRICERATOPS
Pubis Dorsal vertebrae
Parietosquamosal
SKULL AND MANDIBLE
OF STYRACOSAURUS frill Ilium
Hip joint
Cranium
Postorbital Parietal
bone fenestra
Nasal bone
Orbit
Lacrimal
bone
Naris Infratemporal
fenestra
Beak
Jugal bone
Rostral
bone
Predentary Surangular
bone bone
Dentary Angular bone
bone Tooth
Mandible Rib
Ischium
SKULL AND MANDIBLE
OF PROTOCERATOPS Scapula
Femur
Humerus
Knee joint
Fibula
Tibia Elbow Sternal
Neural spine joint bone
Ankle joint
Caudal vertebra
Ulna Coracoid
Chevron Metatarsals
Shoulder
joint
Phalanges
Radius
SKELETON OF TRICERATOPS


102

MARGINOCEPHALIANS 2


EXTERNAL FEATURES Eye EXAMPLES OF CERATOPSIA
OF PSITTACOSAURUS

Cheek horn
Scaly skin Beak
Claw PROTOCERATOPS
Thigh Group: Protoceratopsidae
Finger Length: 9 ft (2.7 m)
Elbow Forelimb

Knee
Claw

Toe
Ankle
Hind limb
STYRACOSAURUS
Group: Centrosaurinae
Parietosquamosal Tail Length: 18 ft (5.5 m)
frill







Brow horn
Cranium core
Orbit
TRICERATOPS
Group: Chasmosaurinae
Length: 30 ft (9.1 m)

Nose horn
core
Cervical
rib
Naris

Infratemporal
fenestra
PACHYRHINOSAURUS
Group: Centrosaurinae
Jugal bone
Length: 18 ft (5.5 m)
Tooth
Metacarpals Mandible
Rostral bone
Phalanges
Predentary
bone LEPTOCERATOPS
Group: Leptoceratopsidae
Length: 7 ft (2.1 m)
103

PREHISTORIC EAR TH

Mammals 1

MODEL OF A
MEGAZOSTRODON
SINCE THE EXTINCTION of most of the dinosaurs 65 million years
ago, mammals (along with birds) have been the dominant vertebrates
on land. This class includes terrestrial, aerial, and aquatic forms.
Having developed from the therapsids, the first true mammals—
small, nocturnal, shrewlike creatures, such as Megazostrodon-
TETRALOPHODON appeared over 200 million years ago during the Triassic period
CHEEK TEETH (250–200 million years ago). Mammals had several
features that differed from those of their ancestors: an efficient
four-chambered heart allowed these warm-blooded animals Long tail aids Insulating
balance
to sustain high levels of activity; a covering of hair helped them hair
maintain a constant body temperature; an improved limb
structure gave them more efficient locomotion; and the birth of live
young and the immediate supply of food from the mother’s milk aided their
rapid growth. Since the end of the Mesozoic era (65 million years ago), the
Neural
number of major mammal groups and the abundance of species in each spine
have varied dramatically. For example, the Perissodactyla (the group
Scapula
that includes Coelodonta and modern horses) was a common group
during the Early Tertiary period (about 54 million years ago). Cervical
Today, the mammalian groups with the most species include the vertebra
Rodentia (rats and mice), the Chiroptera (bats), the Primates
(monkeys and apes), the Carnivora (bears, cats, and dogs),
and the Artiodactyla (cattle, deer, and pigs), while the
Proboscidea group, which formerly included many genera,
such as Phiomia, Moeritherium, Tetralophodon, and
Mammuthus, now has only three species of elephant.
In Australia and South America, millions of years
of continental isolation led to increased diversity
of the marsupials, a group of mammals
distinct from the placentals (see p. 74)
that existed elsewhere.

Humerus








Nasal horn
Naris
Orbit
Radius
Mandible
Premaxilla bone
Ulna

Chisel-edged
molar Metacarpal
Phalanx

104

MAMMALS 1


Cranium
UPPER JAWBONE HOOFBONE (THIRD Naris
(MAXILLA) OF A HORSE PHALANX) OF A HORSE
Premaxilla
bone
Molar
tooth



SKULL AND MANDIBLE
OF A MOERITHERIUM
Articular
surface

Tendon insertion
Molars Premolars
Upper jaw tusk
Molar
Dorsal vertebra
tooth
SKULL AND MANDIBLE
Shovel-
OF A PHIOMIA
shaped
tusk
Ilium
Thick hide
Trunk


Ball and
socket
joint
Short tusk used
for rooting up
Pubis plants
MODEL OF A PHIOMIA
Cranium
Elongated
Rib Femur Mandible Teeth digit
Caudal
vertebra






Fibula
Tibia

Metatarsal
Phalanx
SKELETON OF AN ARSINOITHERIUM
Humerus
Hind limb
bone
FOSSIL SKELETON OF A BAT


105

PREHISTORIC EAR TH

Mammals 2





LOWER JAW OF A BEAR Articulation
with skull
SKELETON OF A TOXODON
Large
canine Diastema Scapula




Neural
Low cusp spine

Molar
Premolar Cervical
vertebra
Zygomatic Cranium
arch
Orbit
Maxilla
Nasal bone



















Incisor Occipital region
Mandible Molar
Humerus
Incisor
Radius Large
breastbone
SKULL OF AN OPOSSUM Ulna
Cranium
Orbit
Metacarpals


Naris



Occipital
region Phalanx
Canine Infraorbital Molar
foramen

106

MAMMALS 2

FOSSIL SKULL OF LOWER JAW OF AN
AN HYAENODON AUSTRALOPITHECUS
Orbit
Sagittal crest
Naris Expanded
Cranium
occlusal
surface

Canine
Neck
insertion
Infraorbital
foramen
Mandible Molar Premolar

Molar
SKULL OF A SMILODON
Orbit
Muscle scar
Naris
Ilium
Sagittal crest
Infraorbital
foramen



Occipital
condyle


Zygomatic
Canine Dentary Slicing arch
bone tooth
Femur

Rib Thick,
insulating
coat
Knee
joint


Fibula
Tibia


Ivory tusk
Metatarsals
Woolly
underhair
Hairy trunk
Phalanx





RECONSTRUCTION OF A MAMMOTH

107

PREHISTORIC EAR TH

The first humans JAWBONE OF AUSTRALOPITHECUS

(SOUTHERN APE)
MODERN HUMANS BELONG TO THE MAMMALIAN order of
primates (see pp. 202–203), which originated about 55 million Larger jawbone
years ago; primates included the only extant hominid species. The than modern
human
earliest hominid was Ardipithecus (“ground ape”) and Australopithecus
(“southern ape”), both small-brained intermediates between apes and
humans that were capable of standing and walking upright. Homo habilis,
the earliest member of the genus Homo, appeared at least 2 million
years ago. This larger-brained “handy man” began making tools for hunting.
Homo ergaster first appeared in Africa about 1.8 million years ago and spread
into Asia about 800,000 years later. Smaller-toothed than Homo habilis,
H. ergaster—followed by Homo erectus—developed fire as a tool, which enabled
it to cook food. Neanderthals, a near relative of modern humans, originated about Large back
200,000 years ago, and Homo sapiens (modern humans) appeared in Africa about tooth
100,000 years later. The two coexisted for thousands of years, but by 30,000 years ago,
Homo sapiens had become dominant and the Neanderthals had died out. Classification
of Homo sapiens in relation to its ancestors is enormously problematic: modern
humans must be classified not only by bone structure, but also by specific
behavior—the ability to plan future action; to follow traditions; and to use
symbolic communication, including complex language and the ability to use 
and recognize symbols.
Cranium
Jutting brow
ridge Orbit
Orbit
Naris
Naris


Jutting
jawbone
SKULL OF AUSTRALOPITHECUS SKULL OF HOMO HABILIS
(SOUTHERN APE) (FIRST MEMBER OF HOMO GENUS)
Well-rounded
cranium
Larger braincase than
Australopithecus Small brow
ridge

Orbit


Orbit Naris



Naris

Small tooth
External
External auditory meatus auditory meatus
SKULL OF HOMO ERECTUS (UPRIGHT MAN) SKULL OF HOMO SAPIENS (MODERN HUMAN)

108

THE FIRST HUMANS

FLINT TOOL MADE ABOUT EXAMPLES OF TOOLS USED
250,000 YEARS AGO BY HOMO SAPIENS
Point
Sharp edge
used to cut Axe used to
meat clear land


Leather binding

Flint may FIRE-MAKING TOOLS
have been Wooden
mouthpiece
carved by
Homo held drill
securely
FLINT HANDAXE erectus FLINT FLAKE
WOODEN MOUTHPIECE
Wooden drill turned
in drill hole to create Bone
spark



Hammer Head used
head used to to mine
detach chips flint
of flint Leather bow
kept drill
upright


BOW DRILL
Handle Handle Handle Drill hole
DRY STRAW


WOODEN HEARTH
ANTLER RED DEER ANTLER FARMING
HAMMER HAMMER AX

EXAMPLES OF PREHISTORIC FOODS SPEAR AND ARROW HEADS



HARPOON POINT
Antler
Twine binding
MINT
FISHING TACKLE
WHEAT GRAINS Wooden point
hardened by fire



Flint glued into WOODEN ARROW
groove cut in shaft


FLINT ARROW
SALMON

109



PLANTS




PLANT VARIETIES . . . . . . . . . . . . . . . . . . . . . . 112
FUNGI AND LICHENS . . . . . . . . . . . . . . . . . . . . 114
ALGAE AND SEAWEEDS . . . . . . . . . . . . . . . . . . . 116
LIVERWORTS AND MOSSES . . . . . . . . . . . . . . . . 118
HORSETAILS, CLUBMOSSES, AND FERNS . . . . . . . 120
GYMNOSPERMS 1 . . . . . . . . . . . . . . . . . . . . . . . 122
GYMNOSPERMS 2 . . . . . . . . . . . . . . . . . . . . . . . 124
MONOCOTYLEDONS AND DICOTYLEDONS . . . . . 126
HERBACEOUS FLOWERING PLANTS . . . . . . . . . . 128
WOODY FLOWERING PLANTS . . . . . . . . . . . . . 130
ROOTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
STEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
LEAVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
PHOTOSYNTHESIS . . . . . . . . . . . . . . . . . . . . . . . 138
FLOWERS 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
FLOWERS 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
POLLINATION . . . . . . . . . . . . . . . . . . . . . . . . . . 144
FERTILIZATION . . . . . . . . . . . . . . . . . . . . . . . . . 146
SUCCULENT FRUITS . . . . . . . . . . . . . . . . . . . . . 148
DRY FRUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
GERMINATION . . . . . . . . . . . . . . . . . . . . . . . . . 152
VEGETATIVE REPRODUCTION . . . . . . . . . . . . . . 154
DRYLAND PLANTS . . . . . . . . . . . . . . . . . . . . . . 156
WETLAND PLANTS . . . . . . . . . . . . . . . . . . . . . 158
CARNIVOROUS PLANTS . . . . . . . . . . . . . . . . . . . 160
EPIPHYTIC AND PARASITIC PLANTS . . . . . . . . . 162

PLANTS

Plant varieties FLOWERING PLANT
Bromeliad
(Acanthostachys strobilacea)
Leaf
THERE ARE MORE THAN 300,000 SPECIES of plant.
They show a wide diversity of forms and life-styles, ranging, for example,
from delicate liverworts, adapted for life in a damp habitat, to cacti, capable of surviving
in the desert, and from herbaceous plants, such as corn, which completes its life-cycle in one year,
to the giant redwood tree, which can live for thousands of years. This diversity reflects the adaptations
of plants to survive in a wide range of habitats. This is seen most clearly in the flowering plants (phylum
Angiospermophyta), which are the most numerous, with over 250,000 species, and the most widespread,
being found from the tropics to the poles. Despite their diversity, plants share certain characteristics: typically,
plants are green, and make their food by photosynthesis; and most plants live in or on a substrate, such as
soil, and do not actively move. Algae (kingdom Protista) and fungi (kingdom Fungi) have
some plantlike characteristics and are often studied alongside plants, although they
GREEN ALGA
Micrograph of desmid are not true plants.
(Micrasterias sp.)
FERN
Tree fern
(Dicksonia antarctica)

Pyrenoid
(small protein
body)


Chloroplast









Sinus Cell wall Rachis
(division between (main axis
two halves of cell) of pinnate leaf)
BRYOPHYTE
Moss Petiole
(Bryum sp.) Seta (leaf stalk)
(stalk)
Immature capsule
Ramentum
(brown scale)
Sporophyte
(spore- Base of dead Trunk
producing Capsule frond (leaf)
plant) (site of spore
production)
Adventitious
root
“Leaf” Gametophyte
(gamete-producing
plant) Epiphytic
fern growing
at base





112

PLANT YARIETIES
FLOWERING PLANT
Succulent
(Kedrostis africana)
Petiole
Spine Flower FLOWERING PLANT (leaf stalk)
Micrograph of cross-section Leaf
Bract through leaf of marram grass
(leaflike structure) (Ammophila arenaria)
Sclerenchyma
Inflorescence (strengthening
Cuticle tissue)
(waterproof
covering) Stem
Stem Xylem
Vascular
Stiff trichome Phloem tissue
(hair)
Interlocked
trichomes (hairs) Caudex
Epidermis (swollen
(outer layer stem
of cells) base)

Hinge cells Mesophyll
(cause curling of leaf to (photosynthetic
reduce water loss) tissue)

Root
Pinna FLOWERING PLANT
(leaflet) Couch grass FLOWERING PLANT
(Agropyron repens) Pitcher plant
(Sarracenia purpurea)
Sepal
Fruit
Caryopsis surrounded
(type of by floral parts
Rachis dry fruit)
(main axis of
grass inflorescence)
Umbrella
of style Pitcher (leaf
Frond (leaf) modified to trap
Pedicel insects)
(flower
stalk)
Hood
Node
Downward-pointing
hair (encourages
insect prey into
pitcher)
Midrib of
pinna (leaflet)
Wing



Lamina
(blade)
Round, hollow Sheathing
stem leaf base
Immature
Adventitious pitcher
root

113

PLANTS

Fungi and lichens EXAMPLES OF FUNGI


Emerging Pileus (cap) Bark
FUNGI WERE ONCE THOUGHT OF AS PLANTS but are now classified as sporophore continuous with of dead
a separate kingdom. This kingdom includes not only the familiar (spore-bearing stipe (stalk) beech tree
structure)
mushrooms, puffballs, stinkhorns, and molds, but also yeasts,
smuts, rusts, and lichens. Most fungi are multicellular, consisting
of a mass of threadlike hyphae that together form a mycelium.
However, the simpler fungi (e.g., yeasts) are microscopic,
single-celled organisms. Typically, fungi reproduce by means of
spores. Most fungi feed on dead or decaying matter, or on living
organisms. A few fungi obtain their food from plants or algae,
with which they have a symbiotic (mutually advantageous)
relationship. Lichens are a symbiotic partnership between
algae and fungi. Of the six types of lichens, the three most
common are crustose (flat and crusty), foliose (leafy), and
fruticose (shrublike). Some lichens (e.g., Cladonia floerkeana)
are a combination of types. Lichens
EXAMPLES reproduce by means of spores or Inrolled
OF LICHENS margin
soredia (powdery vegetative
of pileus
fragments). (cap) Gill Sporophore Stipe Hyphae
(site of spore (spore-bearing (stalk) (fungal
production) structure) filaments)
Secondary fruticose OYSTER FUNGUS
thallus
(Pleurotus pulmonarius)
Toothed
Branched, hollow stem Gleba branchlet
(spore-producing
Apothecium
(spore-producing body) tissue found in Branch
FRUTICOSE this type of fungus)
Cladonia portentosa Sporophore
Sporophore Porous stipe (spore-bearing
Soredia (powdery vegetative (spore-bearing (stalk) structure)
fragments) produced at structure)
end of lobe
Tree bark Volva
(remains of
Foliose universal
thallus veil) Stipe (stalk)
STINKHORN RAMARIA FORMOSA
FOLIOSE (Phallus impudicus)
Hypogymnia physodes Soredium (powdery vegetative
SECTION THROUGH FOLIOSE LICHEN fragment involved in propagation)
SHOWING REPRODUCTION released from lichen
Soredia (powdery vegetative Algal cell
fragments) released onto BY SOREDIA
surface of squamulose Apothecium Fungal hypha
thallus (spore-producing Upper
cortex
body)
Basal scale Algal
of primary layer
squamulose
thallus Medulla of
fungal hyphae
(mycelium)
Moss Podetium
(granular stalk) Lower Soralium
SQUAMULOSE (SCALY) of secondary cortex Rhizine (pore in
AND FRUTICOSE THALLUS fruticose thallus (bundle of upper surface Upper surface
Cladonia floerkeana absorptive hyphae) of thallus) of thallus

114

FUNGI AND LICHENS
LIFE-CYCLE OF A MUSHROOM
Exoperidium Peridium (wall surrounding
spore-producing tissue) Velar scale Pileus (cap)
Endoperidium (remains of
Gleba Scale on universal veil)
(spore-producing exoperidium
tissue found in (outer part of
Gill
this type of fungus) peridium) Annulus
(site of spore
(ring)
production)
Stipe
(stalk)
Underground
mycelium
MATURE SPOROPHORE
Sporophore (SPORE-BEARING STRUCTURE)
(spore-bearing
structure)
Basidium
(spore-
producing
structure) Discharged spore
SECTION OF GILL
Primary
mycelium Spore
develops
Stipe from spore
(stalk)
Underground mycelium Substratum of woodland Primary Septum Hypha
Fan-shaped (mass of hyphae) soil and leaf litter mycelia fuse (cross wall)
pileus (cap) COMMON PUFFBALL to produce
(Scleroderma citrinum) secondary
mycelium
Nucleus

SPORES GERMINATE AND
PRODUCE MYCELIUM
Sporophore
(spore-bearing Immature
structure) sporophore
Pileus Mycelium
(cap)
MYCELIUM FORMS SPOROPHORE
Stipe Gill (site of
(stalk) spore production) Universal veil Pileus
Stipe
(membrane (cap)
HOHENBUEHELIA PETALOIDES Sporophore (stalk) enclosing developing
(spore-bearing sporophore) Gill
structure)
Stipe
Underground
mycelium (stalk)
SPOROPHORE GROWS
ABOVE GROUND
Substratum Expanding Partial veil
of woodland pileus (cap) (joins pileus
soil and leaf to stipe)
litter Annulus (ring)
being formed as Stipe
partial veil breaks (stalk)
Volva
Underground (remains
mycelium of
universal
veil)
FRINGED CRUMBLE CAP Hyphae UNIVERSAL VEIL
(Psathyrella candolleana) (fungal filaments) BREAKS
115

PLANTS

Algae and seaweeds BROWN SEAWEED
Channelled wrack
(Pelvetia canaliculata)
Receptacle
(fertile tip
ALGAE ARE NOT TRUE PLANTS. They form a diverse group of frond)
of plantlike organisms that belong to the kingdom Protista.
Like plants, algae possess the green pigment chlorophyll Thallus
(plant
and make their own food by photosynthesis (see pp. 138-139).
body)
Many algae also possess other pigments by which they can be
classified; for example, the brown pigment fucoxanthin is Apical
found in the brown algae. Some of the 10 phyla of algae are notch
exclusively unicellular (single-celled); others also contain Margin of
lamina (blade) Hapteron (holdfast)
aggregates of cells in filaments or colonies. Three phyla— rolled inward to
the Chlorophyta (green algae), Rhodophyta (red algae), form channel BROWN SEAWEED
Spiral wrack
and Phaeophyta (brown algae)—contain larger, multicellular, (Fucus spiralis)
thalloid (flat), marine organisms commonly known as seaweeds. Apical notch
Most algae can reproduce sexually. For Conceptacle
EXAMPLES OF ALGAE (chamber)
example, in the brown seaweed
Reproductive Receptacle
chamber Fucus vesiculosus, gametes
(sex cells) are produced in (fertile tip Thallus
Cap conceptacles (chambers) in of frond) (plant
Sterile whorl body)
the receptacles (fertile tips
Lamina
of fronds); after their release
Cell wall (blade)
into the sea, antherozoids
Stalk
(male gametes) and oospheres Smooth margin
(female gametes) fuse; the
Rhizoid Midrib Hapteron (holdfast)
resulting zygote settles on a rock
GREEN ALGA and develops into a new seaweed. Apical notch
Acetabularia sp.
Coenobium
Flagellum
Eyespot Contractile (colony of cells) Spine
vacuole
Receptacle
Daughter
Cytoplasm Cytoplasm (fertile tip
coenobium
of frond)
Nucleus
Cell Girdle Vacuole
wall Chloroplast Gelatinous
sheath Plastid Conceptacle
Pyrenoid Nucleus (photosynthetic (chamber)
(small protein
Starch organelle) containing
grain body) Biflagellate cell reproductive
GREEN ALGA GREEN ALGA DIATOM Lamina Midrib structures)
Chlamydomonas sp. Volvox sp. Thalassiosira sp. (blade)
BROWN SEAWEED RECEPTACLE
Oarweed Spiral wrack
(Laminaria digitata) Thallus (plant body) (Fucus spiralis)






Lamina (blade)
palmately
divided

ALGAE AND SEAWEEDS
Crinkled margin GREEN SEAWEED RED SEAWEED LIFE-CYCLE OF BROWN SEAWEED
Enteromorpha linza Corallina officinalis Bladder wrack
(Fucus vesiculosus)
Branch
Male Female
Branched, receptacle receptacle
hard thallus
(plant body)

Lamina
Air bladder (blade)
Thallus Stipe
(plant Unbranched, Hapteron Main Hapteron (stalk)
body) spirally twisted (holdfast) stem (holdfast)
frond
MALE AND FEMALE SEAWEEDS
Female
Small hapteron Male receptacle
(holdfast) attaching receptacle
seaweed to mussel
Conceptacle
RED SEAWEED Ostiole
Dilsea carnosa (opening to
conceptacle)
MALE AND FEMALE RECEPTACLES
Paraphysis
(sterile hair)
Ostiole
(opening to
conceptacle)
Antheridium
Thallus
(male sex
(plant organ)
body) Oogonium
(female sex organ)
SECTIONS THROUGH MALE AND FEMALE
CONCEPTACLES
Oogonium
Antherozoid
(male gamete)
Lamina
(blade) Antheridium
(male sex organ)
Oosphere
(female
gamete)
PRODUCTION OF GAMETES
Hapteron
(holdfast) Antherozoid (male Oosphere
GREEN ALGA gamete) swims (female
Spirogyra sp. toward oosphere gamete) is
fertilized by
Cytoplasm Flagellum antherozoid
End wall
to produce
Cell (cylindrical) of cell
a zygote
Cell wall
Flexible stipe FERTILIZATION
(stalk)
Filament
(strand of
linked cells)
Spirally Young thallus
wound
Two filaments (plant body)
linked for chloroplast
conjugation
(sexual Conjugation Hapteron
Hapteron tube (holdfast)
reproduction)
(holdfast)
ZYGOTE DEVELOPS INTO
End wall of conjugation
tube still in place A YOUNG SEAWEED
117

PLANTS

Liverworts and mosses A LEAFY LIVERWORT
Scapania undulata
“Stem”

LIVERWORTS AND MOSSES ARE SMALL, LOW-GROWING PLANTS that belong to the phylum
Bryophyta. Bryophytes do not have true stems, leaves, or roots (they are anchored to
the ground by rhizoids), nor do they have the vascular tissues (xylem and phloem)
that transport water and nutrients in higher plants. With no outer, waterproof “Leaf”
cuticle, bryophytes are susceptible to drying out, and most grow in moist habitats.
The bryophyte life-cycle has two stages. In stage one, the green plant (gametophyte)
produces male and female gametes (sex cells), which fuse to form a zygote. In stage
two, the zygote develops into a sporophyte that remains attached to the gametophyte.
The sporophyte produces spores, which are released and germinate into new green
plants. Liverworts (class Hepaticae) grow horizontally and may be thalloid (flat and Rhizoid
ribbonlike) or “leafy.” Mosses (class Musci) typically have an upright “stem” with
spirally arranged “leaves.”

Disk Disk Ray
Lobe (radial groove)
A THALLOID LIVERWORT Archegoniophore Lobe Lobe
Marchantia polymorpha (stalked structure Stalk
carrying archegonia) Stalk Disk
Gemma cup Thallus
(plant body) Stalk ARCHEGONIOPHORE
FROM BELOW
Gemma (detachable
tissue that produces
new plants)
Thallus Apical
(plant body) notch Rhizoid
Toothed margin SIDE VIEW OF
DETAIL OF GEMMA CUP of cup ARCHEGONIOPHORE
Pore
Thallus FEMALE
Gemma cup (plant body) GAMETOPHYTE
Ray
Midrib (radial groove)
Archegoniophore
(stalked structure MICROGRAPH OF LOBE
carrying archegonia)
MICROGRAPH OF THALLUS
Conocephalum conicum


Position
of air
chamber
Pore for
exchange
of gases






Upper
surface Rhizoid



118

LIVER WOR TS AND MOSSES
A COMMON MOSS MICROGRAPH OF MOSS SPORE LIFE-CYCLE OF MOSS
Branch of
Polytrichum commune Funaria hygrometrica Funaria sp.
conducting
tissue to “leaf”
Female rosette
“Stem” Cortex Male rosette (“leaves”
(“leaves” around around
archegonia)
antheridia)
Lateral
Main “stem” branch
of “stem”
Rhizoid
Epidermis Archegonium
(outer layer (female sex
of cells) GAMETOPHYTE organ)
Central strand Antherozoids
“Leaf” of conducting (male gametes)
tissue Epidermis released from
of capsule antheridium
Midrib
Antheridium
MICROGRAPH OF CROSS-SECTION (male sex organ)
THROUGH STEM AND LEAF
Remains of
SECTION THROUGH
SECTION THROUGH
Capsule Spore-containing spore-forming MATURE MALE APEX MATURE FEMALE APEX
Apophysis space tissue
(swollen area between Flagellum
seta and capsule) Columella
(central tissue Archegonium
Columella of capsule) Antherozoid (female sex
(central tissue (male gamete) organ)
of capsule) CROSS-SECTION swims to
THROUGH CAPSULE oosphere Oosphere (female
gamete) fertilized
Operculum by antherozoid
Beak (lid)
FERTILIZATION
Male apex
Calyptra (“leaves”
(hood surrounding
covering antheridia) Capsule Sporophyte
capsule) grows from
“Leaf” Seta fertilized
(stalk) oosphere
Seta
“Leaf” Gametophyte
(stalk) Young
aerial
“stem”
SPOROPHYTE
Capsule Apophysis
“Stem”
Seta
Operculum (stalk)
(lid)
Air space
Peristome Spores
tooth opens dispersed
RIPE CAPSULE
“Stem”
Young
gametophyte
Bud
Protonema
(branched
green filament) Spore
Rhizoid
EXTERNAL VIEW
DEVELOPING
OF MOSS
GAMETOPHYTE
119

PLANTS

Horsetails, clubmosses, CLUBMOSS
Lycopodium sp.

and ferns



HORSETAILS, CLUBMOSSES, AND FERNS are primitive land Stem with
spirally
plants, which, like higher plants, have stems, roots, and leaves,
arranged
and vascular systems that transport water, minerals, and food. leaves
However, unlike higher plants, they do not produce seeds when
Branch
reproducing. Their life-cycles involve two stages. In stage one,
the sporophyte (green plant) produces spores in sporangia.
In stage two, the spores germinate, developing into small,
short-lived gametophyte plants that produce male and female
gametes (sex cells); the gametes fuse to form a zygote from
which a new sporophyte plant develops. Horsetails (phylum
FROND
Male fern Sphenophyta) have erect, green stems with branches
(Dryopteris arranged in whorls; some stems are fertile and have a single
filix-mas)
spore-producing strobilus (group of sporangia) at the tip.
Clubmosses (phylum Lycopodophyta) typically have small leaves arranged
spirally around the stem, with spore-producing strobili at the tip of some
stems. Ferns (phylum Filicinophyta) typically Strobilus
CLUBMOSS (group of sporangia)
have large, pinnate fronds (leaves); Selaginella sp.
sporangia, grouped together in sori, Cortex (layer
Epidermis between epidermis
develop on the underside (outer layer and vascular tissue) Shoot
of fertile fronds. of cells) apex
Branch
Rhizophore
HORSETAIL Vascular Phloem (leafless
Common horsetail tissue branch)
(Equisetum arvense) Apex of Xylem
sterile shoot
Sporangiophore
(structure Lacuna
carrying (air space)
sporangia)
Creeping stem with
MICROGRAPH OF CROSS-SECTION spirally arranged
THROUGH CLUBMOSS STEM leaves
Strobilus
(group of
sporangia) Endodermis Vascular tissue
Lateral (inner layer Sclerenchyma
branch of cortex) (strengthening tissue)
Chlorenchyma
Photosynthetic Epidermis (photosynthetic
sterile stem (outer layer tissue)
Non-photosynthetic of cells)
fertile stem Node Parenchyma
(packing
Young Internode Cortex tissue)
shoot (layer between
Collar of small Tuber epidermis and Hollow pith
Node
brown leaves vascular tissue) cavity
Vallecular canal Carinal canal
(longitudinal channel) (longitudinal
channel)
Rhizome MICROGRAPH OF CROSS-SECTION
Adventitious root THROUGH HORSETAIL STEM

120

HORSETAILS, CLUBMOSSES, AND FERNS
SPORE PRODUCTION IN FERN Sporangium LIFE-CYCLE OF FERN
Bracken (spore-producing Annulus
(Pteridium Apex of structure) (ring of cells
pinnule
aquilinum) Spore around sporangium) Pinna (leaflet)
Sporangium Pinnule (leaflet
(spore-producing
Pinnule structure) of pinna) Frond
(leaflet (leaf)
of Spore inside Rolled
pinna) dehisced immature
(split open) frond
sporangium
Abaxial Pinnule SPOROPHYTE Rhizome
(lower)
(leaflet Placenta
surface of of pinna)
pinnule
Indusium
Sorus
Midrib of (group of (flap
protecting
pinnule sporangia) Midrib of pinnule sorus) Sorus
(group of
MICROGRAPH OF SPORANGIA ON
MICROGRAPH OF LOWER SURFACE Sporangium sporangia)
LOWER SURFACE OF FERTILE (spore-producing structure)
OF FERTILE PINNULE
PINNULE
SECTION THROUGH MATURE PINNULE
Midrib Apex of frond (leaf)
FERN of pinna Sporangium
Male fern (leaflet) splits and
(Dryopteris filix-mas) Annulus releases spores
ruptures
Pinna at weak
(leaflet) point
Spore
RELEASE OF SPORES
FROM SPORANGIUM
Spore Filament
develops
into
Rhizoid
Pinnule prothallus
(leaflet of
pinna) GERMINATION OF SPORE
Archegonium
Frond Antheridium (female sex
(leaf) (male sex organ)
organ)
Prothallus
(free-living
Young frond gametophyte) Rhizoid
(leaf) GAMETOPHYTE PRODUCES GAMETES
Young frond
Rachis (leaf) rolled
(main axis of and covered
pinnate leaf) by ramenta Antheridium
(male sex Oosphere
organ)
Base of Ramentum (female
Sclerenchyma old dead (brown scale) gamete)
Vascular (strengthening tissue) frond (leaf)
bundle Rhizome Antherozoid
Phloem (male gamete) Archegonium
Vascular swims to (female sex organ)
Xylem tissue oosphere FERTILIZATION
Primary leaf
of growing Remains of
sporophyte gametophyte
Epidermis
(outer layer
Parenchyma of cells)
(packing tissue)
MICROGRAPH OF CROSS-SECTION Adventitious root FERTILIZED OOSPHERE GROWS
THROUGH FERN RACHIS INTO NEW SPOROPHYTE PLANT
121

PLANTS

Gymnosperms 1 LIFE-CYCLE OF SCOTS PINE
(Pinus sylvestris)

Needle
THE GYMNOSPERMS ARE FOUR RELATED PHYLA of seed-producing (foliage
plants; their seeds, however, lack the protective, outer covering leaf)
that surrounds the seeds of flowering plants. Typically,
Cone Ovuliferous scale
gymnosperms are woody, perennial shrubs or trees, with stems, (ovule- then seed-
leaves, and roots, and a well-developed vascular (transportat) system. bearing structure)
The reproductive structures in most gymnosperms are cones: male MALE CONES YOUNG FEMALE CONE
cones produce microspores in which male gametes (sex cells) develop; Pollen grain in micropyle Ovuliferous
female cones produce megaspores in which female gametes develop. (entrance to ovule) scale
Microspores are blown by the wind to female cones, male and female Pollen
gametes fuse during fertilization, and a seed develops. The four grain Ovule
(contains
gymnosperm phyla are the conifers (phylum Coniferophyta), mostly
Nucleus female
tall trees; cycads (phylum Cycadophyta), small palmlike Air sac gamete)
trees; the ginkgo or maidenhair tree POLLINATION
SCALE AND SEEDS
(phylum Ginkgophyta), a tall tree with
Pine Integument
bilobed leaves; and gnetophytes (Pinus sp.) (outer part Archegonium
(phylum Gnetophyta), a diverse Ovuliferous scale of ovule) (containing
(ovule- then seed-
group of plants, mainly shrubs, bearing structure) Wing Pollen tube female
but also including the scar (carries male gamete)
horizontally growing gamete from FERTILIZATION
Wing of seed pollen grain
welwitschia. derived from to ovum)
ovuliferous scale
Seed Seed
Microsporangium Seed
(structure in which Seed
pollen grains are Ovuliferous Wing
Seed scar
formed) Point of attachment scale
to axis of cone (ovule- then
OVULIFEROUS SCALE FROM seed-bearing
THIRD-YEAR FEMALE CONE structure) MATURE FEMALE CONE AND
WINGED SEED
Microsporophyll
(modified leaf
carrying Ovule
microsporangia) (contains Plumule Cotyledon
female (embryonic (seed leaf)
gametes) shoot)
Root
Bract
scale
GERMINATION OF
Scale leaf PINE SEEDLING
Axis
of cone Ovuliferous scale
(ovule- then seed- Axis
bearing structure) of cone
WELWITSCHIA
MICROGRAPH OF LONGITUDINAL MICROGRAPH OF LONGITUDINAL (Welwitschia mirabilis)
SECTION THROUGH YOUNG SECTION THROUGH SECOND-YEAR
MALE CONE FEMALE CONE

Frayed end of leaf






122

GYMNOSPERMS 1
SMOOTH CYPRESS YEW
(Cupressus glabra) (Taxus baccata)

Immature Ovuliferous
female scale
cone Ovule
(contains female
gamete)
Ovuliferous scale CROSS-SECTION THROUGH
(ovule- then seed- IMMATURE CONE
bearing structure)
Ovuliferous scale
(ovule- then seed-
Seed bearing structure)
Single ovule
Scalelike (contains female
leaf gamete)

CROSS-SECTION Scale
THROUGH MATURE Seed
Mature CONE Female “cone”
female Immature Aril
cone male cone Scale (fleshy
Opening between outgrowth
woody scales Developing from seed)
Woody through which seed
scale seeds are Scale Stem
released
DISCARDED CONE FEMALE “CONES” AT
Stem VARIOUS STAGES OF Needle
DEVELOPMENT (foliage
CYCAD leaf)
Sago palm
(Cycas revoluta)
Pinna MAIDENHAIR TREE
(leaflet) (Ginkgo biloba) Girdle scar

Pinnate leaf Stem


Scale
leaf Petiole
(leaf stalk)





Old leaf base Bilobed leaf
Stem covered
Continuously by scale leaves
growing leaf
Adaxial (upper)
Site of cone surface of leaf
growth
Frayed end of leaf
Abaxial (lower)
surface of leaf
Immature
cone
Stalk
scar Woody stem


123

PLANTS

Gymnosperms 2



Second-year female cone
BRANCH OF BISHOP PINE
(Pinus muricata) Ovuliferous scale
Needle (ovule- then seed-bearing
(foliage leaf) structure)
Ovuliferous scale
(ovule- then seed-
bearing structure)

Bud Cone
scale
Apical bud
Cone stalk
Stem
Dwarf shoot
Scale leaf scar
FEMALE CONE
(FIRST YEAR)




Stem





Male cone Needle (foliage leaf)
Dwarf shoot
Margin
Upper surface of needle
of needle (foliage leaf)
(foliage leaf)
Needle
(foliage leaf)
Apical bud




Scar of Dwarf shoot
dwarf shoot Stem
TERMINAL ZONE OF BRANCH
Stoma
(pore)
Vascular tissue Mesophyll
(photosynthetic tissue)
Phloem Xylem
Epidermis
Female
(outer
cone
Stoma layer of
(pore) cells)
Woody ovuliferous Cuticle
scale (ovule- then Endodermis (waterproof
seed-bearing structure) (inner layer Resin canal covering)
of cortex) MICROGRAPH OF NEEDLE
FEMALE CONE MICROGRAPH OF CROSS-SECTION (FOLIAGE LEAF) OF PINE
(THIRD YEAR) THROUGH NEEDLE (FOLIAGE LEAF) (Pinus sp.)
124

CROSS-SECTION THROUGH
Apical bud scale MATURE STEM OF BISHOP PINE
(Pinus muricata)
Apical bud
Annual ring
Shoot
apex
Immature needle
(foliage leaf)
Needle
(foliage
leaf) bud


Bud scale
Heartwood
(supportive,
Scale leaf inactive
secondary
xylem)
MICROGRAPH OF LONGITUDINAL SECTION
THROUGH SHOOT APEX OF PINE Branch trace
(Pinus sp.) (vascular bundle
supplying branch)
Pith
Hypodermis
Medullary ray (cell layer below
(extension of pith) epidermis)
Cortex Base of dwarf shoot
(layer between Pith
epidermis and
vascular tissue)
Dwarf shoot trace
(vascular bundle
supplying dwarf Sapwood
shoot)
Secondary (active secondary
xylem Epidermis xylem)
(outer layer
Vascular Phloem of cells) Phloem
tissue Bark Periderm
Primary Resin canal (outer layer
xylem
of bark)
MICROGRAPH OF CROSS-SECTION Cortex
THROUGH YOUNG STEM OF PINE (layer between
(Pinus sp.) phellem and
Cortex vascular tissue)
(layer between Resin canal
phellem and Secondary Primary
vascular tissue)
xylem xylem
Endodermis
Phellem
(inner layer (protective
of cortex)
outer layer)
Secondary
Phloem xylem


Primary
Phellem
(protective xylem Resin canal
Phloem
outer layer)
MICROGRAPH OF CROSS-SECTION MICROGRAPH OF CROSS-SECTION
THROUGH YOUNG ROOT OF PINE THROUGH MATURE ROOT OF PINE
(Pinus sp.) (Pinus sp.)

125

PLANTS

Monocotyledons COMPARISONS BETWEEN
MONOCOTYLEDONS AND
DICOTYLEDONS
and dicotyledons Vein Leaflet
(parallel
venation)

FLOWERING PLANTS (PHYLUM ANGIOSPERMOPHYTA) are divided into two classes:
monocotyledons (class Monocotyledoneae) and dicotyledons (class
Dicotyledoneae). Typically, monocotyledons have seeds with
one cotyledon (seed leaf); their foliage leaves are narrow with Petiole
parallel veins; the flower components occur in multiples of (leaf stalk)
three; sepals and petals are indistinguishable and are known
as tepals; vascular (transport) tissues are scattered in random
CROSS-SECTION bundles throughout the stem; and, since they lack stem Emerging
THROUGH leaf
MONOCOTYLEDONOUS cambium (actively dividing cells that produce wood),
LEAF BASES most monocotyledons are herbaceous (see pp. 128-129).
Dicotyledons have seeds with two cotyledons; leaves are broad with a central
midrib and branched veins; flower parts occur in multiples of four or five;
sepals are generally small and green; petals are large and colorful; vascular Leaf base
bundles are arranged in a ring around the edge of the stem; and, because many
dicotyledons possess wood-producing stem cambium, there are woody forms
(see pp. 130-131) as well as herbaceous ones. Adventitious
root
Xylem
Vascular tissue
Water-absorbing A MONOCOTYLEDON
parenchyma Mesophyll Phloem Palisade mesophyll Paradise palm
(photosynthetic (tightly packed
(packing (Howea forsteriana)
tissue) tissue) photosynthetic tissue)
Vein Collenchyma
Spongy
mesophyll (supporting
(loosely packed tissue)
Sunken Vein
stoma photosynthetic
tissue) Vascular Xylem
(pore) tissue Epidermis
Epidermis Phloem (outer layer
Cuticle (outer layer of cells) of cells)
(waterproof Sclerenchyma Parenchyma
covering) (strengthening tissue) (packing tissue)
Midrib
MICROGRAPH OF CROSS-SECTION THROUGH MICROGRAPH OF CROSS-SECTION THROUGH
A MONOCOTYLEDONOUS LEAF A DICOTYLEDONOUS LEAF
Yucca (Yucca sp.) Crab apple (Malus sp.)
Lateral, inner tepal
Outer tepal (monocotyledonous
(monocotyledonous petal) Filament Stigma
sepal) Stamen
Anther
Pollen on
anther
Column
(stamens
and style)

Funnel guide for Petal
bird pollinators’ beak
Guide hair
Labellum (lip)
A MONOCOTYLEDONOUS FLOWER forming landing stage A DICOTYLEDONOUS FLOWER
Orchid for pollinator Hibiscus
(Phalaenopsis sp.) (Hibiscus rosa-sinensis)

126

Stigma Petal Flower bud
Sepal Pedicel
Anther
Plicate (folded) Stamen (flower stalk)
lamina (blade) Filament Bract
of young leaf (leaflike structure)
Petiole
(leaf stalk) Receptacle
Node

Lora
(strip of Lamina
dead cells) (blade)
Leaf
Petiole
(leaf stalk) Stem



Leaf base Branch
Lateral
Vein bud
(branched venation)
MONOCOTYLEDONOUS LEAF BASES FORMING STEM
Chusan palm
(Trachycarpus fortunei) Midrib
Stem
Bud scale Pith
leaf Axillary bud
(bud developing
between leaf and stem)
Main root
Petiole
(leaf Immature Lateral root
stalk) foliage leaf
Vascular supply
to axillary bud
Leaf base Phellem
(protective cork layer)
Leaf trace Vascular tissue of stem
(vascular bundle supplying leaf) (xylem and phloem)
MICROGRAPH OF LONGITUDINAL SECTION THROUGH
A DICOTYLEDON
A WOODY DICOTYLEDONOUS STEM Hibiscus (Hibiscus rosa-sinensis)
Maple (Acer sp.)
Pericycle Protoxylem Metaxylem
(outer layer Xylem Xylem
of stele) Metaxylem
Protoxylem
Epidermis Cortex
(outer layer (layer between Epidermis
of cells) epidermis and (outer layer
vascular tissue) of cells)
Phloem
Pith
Pericycle
Cortex (outer layer
(layer between of stele)
epidermis and
vascular tissue) Endodermis Phloem Endodermis
(inner layer (inner layer
Stele of cortex) Stele of cortex)
(vascular cylinder) (vascular cylinder)
MICROGRAPH OF CROSS-SECTION THROUGH MICROGRAPH OF CROSS-SECTION THROUGH
A MONOCOTYLEDONOUS ROOT A DICOTYLEDONOUS ROOT
Corn (Zea mays) Buttercup (Ranunculus sp.)
127

PLANTS

Herbaceous flowering plants



HERBACEOUS FLOWERING PLANTS TYPICALLY HAVE GREEN, NON-WOODY STEMS, and tend to be relatively
short-lived. Many herbaceous plants live for only one or two years. Annuals (e.g., sweet peas) grow from
seed, produce flowers and then seeds, and die within a single year. Biennials
(e.g., carrots) have a two-year life cycle. In the first year, seeds grow into plants, Young plant
which produce leaves and store food in underground storage organs; the stems forming
and foliage then die back in winter. In the second year, new stems grow from
the storage organs, produce leaves, flowers, and seeds, and then die. Some
Petiole (stalk)
herbaceous plants (e.g., potatoes) are perennial. They grow back year after year,
of young leaf
producing shoots and flowers in spring,
storing food in underground tubers or
rhizomes during summer, Lateral Stipule
dying back in the fall, root (structure at Trifoliate
base of leaf) leaf
and surviving
underground
Node
during winter. Simple
ovate
Root Main leaflet
nodule root
STRAWBERRY
SWEET PEA (Fragaria x ananassa)
(Lathyrus odoratus)
Runner
(creeping stem)
Remains
Lateral of leaves Leaf
root scar Stem scar Rib


Leaf base
Lateral root Tap
root Leaf Petiole Spine
CARROT scar (leaf (modified
(Daucus carota) stalk) leaf)
Slender
rhizome

Stem Adventitious
tuber root
Stem
Narrow,
succulent leaf Simple
deltoid
leaf
ROCK STONECROP
POTATO (Sedum rupestre)
(Solanum tuberosum)



Adventitious
root







128

HERBACEOUS FLOWERING PLANTS
PARTS OF HERBACEOUS FLOWERING PLANTS



Bracteole
Bract (small bract)
(leaflike
structure)
Midrib
Cyme
Succulent, (type of inflorescence)
simple ovate
leaf Inner, tubular Outer, ligulate
disk floret ray floret

Flower bud
Node
Peduncle
(inflorescence stalk)
Dentate Capitulum
margin (type of inflorescence)
Leaf
Internode
LIVE-FOREVER OR Simple lobed Peduncle
ICE PLANT leaf (inflorescence
(Sedum spectabile) stalk) Flower
bud
Petiole Petiole
(leaf stalk) (leaf
Succulent stalk)
stem Leaf base Stem Linear
Leaf Lateral FLORISTS’ CHRYSANTHEMUM leaf
scar bud Prickle (Chrysanthemum morifolium)



BEGONIA Bract Capitulum Hollow
CEREOID (Begonia x (leaflike (type of stem
CACTUS tuberhybrida) structure) inflorescence) Sheath formed
Spinose-dentate from leaf base TOADFLAX
margin Dentate (Linaria sp.)
Rachis margin Unwinged rachis
(main axis of SLENDER THISTLE (main axis of
Winged pinnate leaf) (Carduus tenuiflorus) pinnate leaf)
stem Peduncle
Stipule Winged (inflorescence
(structure at rachis stalk)
base of leaf) Tendril Stem (main
Flower bud
segment axis of
pinnate
leaf) HOGWEED
Pinna (Heracleum sphondylium)
(leaflet) Bract
Margin of (leaflike Tepal
cladode Toothed structure)
Petiole notch PERUVIAN LILY
(leaf stalk) (Alstroemeria aurea)
Peduncle Cladode
(inflorescence (flattened stem) Stem
stalk) branch
Raceme
(type of inflorescence)
CRAB CACTUS
(Schlumbergera truncala)
EVERLASTING PEA
Petal Sepal (Lathyrus latifolius)

129

PLANTS

Woody flowering plants



WOODY FLOWERING PLANTS ARE PERENNIAL, that is, they continue to grow and reproduce for many years.
They have one or more permanent stems above ground, and numerous smaller branches. The stems and branches
have a strong woody core that supports the plant and contains vascular tissue for transporting water and
nutrients. Outside the woody core is a layer of tough, protective bark, which has lenticels (tiny pores) in it to
enable gases to pass through. Woody flowering plants may be shrubs, which have several stems arising from the
soil; bushes, which are shrubs with dense branching and foliage; or trees, which typically have a single upright
stem (the trunk) that bears branches. Deciduous woody
plants (e.g., roses) shed all their leaves once a year Pinnate Simple
and remain leafless during winter. Evergreen compound entire
leaf leaf
woody plants (e.g., ivy) shed their leaves Dentate
margin
gradually, so retaining full Aggregate fruit
leaf cover throughout (succulent fruit)
the year.
Tendril
BRAMBLE
(Rubus fruticosus)
Trifoliate Rachis
compound
leaf Petiole
Main Prickle (leaf stalk)
root
Leaflet
ROWAN COMMON MULBERRY
(Sorbus aucuparia) (Morus nigra)
CLEMATIS Prickle
(Clematis Internode Lenticel (pore)
montana)

CHUSAN PALM Leaf scar ELDER
(Trachycarpus fortunei) Node Node ROSE (Sambucus
(Rosa sp.)
Stem nigra)
Lateral
Lateral Petiole bud
root (leaf stalk)
Dormant
COMMON HORSE Ring scar bud
CHESTNUT Petiole
(Aesculus Petiole Leaf scar (leaf
hippocastanum) (leaf stalk) stalk)
Adaxial (upper)
surface of
Simple lamina
palmate leaf Leaflet Triple spine
Lora (strip Terminal (modified leaf)
of dead cells) bud
COMMON HORSE CHESTNUT
PASSION FLOWER Tendril (Aesculus hippocastanum)
(Passiflora caerulea)
Palmate
compound leaf
Stipule (structure
at base of tendril)


CHUSAN PALM
(Trachycarpus fortunei)


130

WOODY FLOWERING PLANTS
PARTS OF WOODY FLOWERING PLANTS

DURMAST OAK
(Quercus petraea)
Simple
lobed Midrib
obovate
leaf
Remains
Pinnate of bracts Flower
compound Immature bud
leaf Nut acorn Sepal
(dry fruit) Pedicel Stamen
Receptacle
(flower
stalk)
Petal
Spine Bract
Pinna Sepal
(leaflet) Pedicel (flower
stalk)
Ovary
MAHONIA
Axillary Peduncle
(Mahonia lomariifolia) bud (inflorescence stalk) ROSE
(Rosa sp.)
Pome Stipule
Variegated (succulent (structure at Leaflet
lamina fruit) base of leaf) ROSE
(blade) (Rosa sp.)
Remains Lateral
Adventitious of style ROWAN bud
root (Sorbus
Stem aucuparia) Petal
Petiole
COMMON ENGLISH IVY Ring scar (leaf stalk)
(Hedera helix ‘Goldheart’) Node
Flower bud
Culm BAMBOO ROWAN
(jointed stem) (Arundinaria nitida) (Sorbus aucuparia) Pedicel
(flower
Petiole stalk)
(leaf stalk) Adaxial (upper) Stem
surface of Simple
Petiole
Vein lamina lanceolate leaf
(blade) (leaf stalk)
CLEMATIS
(Clematis sp.)
Peduncle
(inflorescence stalk)
TREE MALLOW
(Lavatera arborea) Peduncle
(inflorescence
Pedicel
Leaf stalk)
Stem (flower Double samara Pedicel
stalk) (winged dry
fruit) Drupe (flower
(succulent stalk)
Wing fruit)
Pericarp (fruit wall) PEACH
enclosing seed (Prunus persica)
Triple spine Compound
(modified inflorescence
leaf) (panicle)
BARBERRY SYCAMORE RUSSIAN VINE
(Berberís sp.) (Acer pseudoplatanus) (Polygonum baldschuanicum)




131

PLANTS

Roots MICROGRAPH OF PRIMARY ROOT DEVELOPMENT
Cabbage (Brassica sp.)
Split in testa Cotyledon Primary root
as seed (seed leaf)
ROOTS ARE THE UNDERGROUND PARTS OF PLANTS. They have germinates
three main functions. First, they anchor the plant in the soil.
Second, they absorb water and minerals from the spaces
between soil particles; the roots’ absorptive properties are
increased by root hairs, which grow behind the root tip,
allowing maximum uptake of vital substances. Third, the
root is part of the plant’s transport system: xylem carries
Testa Root hair
water and minerals from the roots to the stem and leaves,
(seed coat)
and phloem carries nutrients from the leaves to all parts of
the root system. In addition, some roots (e.g., carrots) are food
stores. Roots have an outer epidermis covering a cortex of parenchyma
(packing tissue), and a central cylinder of vascular tissue. This arrangement
helps the roots resist the forces of compression as they grow through the soil.

CARROT FEATURES OF A TYPICAL ROOT Phloem sieve tube Root tip
(Daucus carota) Buttercup (through which (region of
(Ranunculus sp.) Stele nutrients are cell division)
(vascular cylinder) transported)
Pericycle Companion cell
(outer layer (cell associated
of stele) with phloem
sieve tube)
Root hair
Cortex
(layer between
epidermis and
Air space vascular tissue)
(allowing gas
diffusion in Root hair
the root)



























Cell wall
Epidermis Xylem vessel Endodermis Nucleus Parenchyma
(outer layer (through which water (inner layer (packing) cell
of cells) and minerals are transported) of cortex) Cytoplasm

132

ROOTS
PRIMARY ROOT AND MICROGRAPHS OF SECTIONS THROUGH ROOTS
Stele
(vascular
Lateral root cylinder)

Apical meristem Primary root
(region of actively
dividing cells)
Elongating region
Root cap
(protects
dividing Epidermis
cells) (outer layer
of cells) Cortex
(layer between
epidermis and Epidermis
Stele vascular tissue) (outer layer
(vascular of cells)
cylinder)
CROSS-SECTION THROUGH ROOT OF BUTTERCUP
(Ranunculus sp.)
Cortex
(layer between Cortex Epidermis
epidermis and (layer between (outer layer
Lateral root vascular tissue) epidermis and of cells)
vascular tissue)
CROSS-SECTION THROUGH ROOT OF FAVA BEAN
(Vicia faba)
Endodermis
(inner layer
Cortex of cortex)
Stele (layer between
(vascular epidermis and
Epidermis cylinder) vascular tissue) Phloem
(outer layer
of cells) Root tip Metaxylem
(region of Stele Protoxylem
cell division) (vascular
cylinder) Pericycle
(outer layer)
PRIMARY ROOT OF FAVA BEAN
(Vicia faba)
CROSS-SECTION THROUGH ROOT OF LILY
(Lilium sp.)
Cortex
(layer between
epidermis and Epidermis
vascular tissue)

Elongating region




Stele
(vascular
cylinder)

Apical meristem
(region of actively
dividing cells)
Hyphae of fungus
Root cap in mycorrhizal
(protects (symbiotic) association Starch grain
dividing cells) with orchid
LONGITUDINAL SECTION CROSS-SECTION THROUGH ROOT OF ORCHID IN
THROUGH ROOT TIP OF FAVA BEAN MYCORRHIZAL ASSOCIATION WITH FUNGUS
(Vicia faba)
133

PLANTS

Stems MICROGRAPH OF LONGITUDINAL
SECTION THROUGH APEX OF STEM
Coleus sp.

THE STEM IS THE MAIN SUPPORTIVE PART OF A PLANT that grows
above ground. Stems bear leaves (organs of photosynthesis), which Apical
meristem Procambial
grow at nodes; buds (shoots covered by protective scales), which grow (region of strand (cells
at the stem tip (apical or terminal buds) and in the angle between a actively that produce
leaf and the stem (axillary or lateral buds); and flowers (reproductive dividing vascular tissue)
cells)
structures). The stem forms part of the plant’s transport system: xylem Leaf primordium
tissue in the stem transports water and minerals from the roots to the (developing leaf)
aerial parts of the plant, and phloem tissue transports nutrients
Developing Cortex
manufactured in the leaves to other parts of the plant. Stem tissues bud (layer between
are also used for storing water and food. Herbaceous (non-woody) epidermis and
vascular tissue)
stems have an outer protective epidermis covering a cortex that
consists mainly of parenchyma (packing tissue) but also has some Vascular
collenchyma (supporting tissue). The vascular tissue of such stems tissue
is arranged in bundles, each of which consists of xylem, phloem, Epidermis
and sclerenchyma (strengthening tissue). Woody stems have an outer Pith (outer layer
protective layer of tough bark, which is perforated with lenticels (pores) of cells)
to allow gas exchange. Inside the bark is a ring of secondary phloem, Young
which surrounds an inner core of secondary xylem. leaves
emerging
YOUNG WOODY STEM EMERGENT BUDS
Lime London plane
(Tilia sp.) (Platanus x acerifolia)

Secondary Pith Phellem
phloem (protective Terminal bud
Cortex cork layer)
(layer between phellem
and vascular tissue)

Xylem vessel
(through which Lateral bud
water and
minerals are
transported) Vascular cambium
(actively dividing cells Node
Xylem fiber that produce xylem
(supporting and phloem) Internode
tissue)
Inner
Ray Fall bud scale
(parenchyma wood
cells) Secondary
Spring xylem
wood
Phloem sieve tube Outer
(through which bud scale
nutrients are
transported) Node Leaf scar
Companion cell
(cell associated
Phloem fiber with phloem
(supporting sieve tube)
tissue) Lenticel
(pore) Woody
Lenticel stem
(pore)


134

STEMS
MICROGRAPHS OF CROSS-SECTIONS THROUGH VARIOUS STEMS Prickle
(outgrowth of epidermis)
Epidermis
(outer layer Vascular cambium Sclerenchyma
of cells) (actively dividing (strengthening
cells that produce tissue)
xylem and phloem)
Collenchyma
Secondary
(supporting
tissue) phloem
Pith
cavity Secondary
xylem Pith
Pith
Primary
xylem
Xylem Cortex
Vascular Cortex Epidermis (layer between
bundle Phloem (layer between (outer layer epidermis and
epidermis and of cells) with thick cuticle vascular tissue)
vascular tissue)
CHERVIL (waterproof covering) ROSE
(Anthriscus sp.) (Rosa sp.)
Secondary Sclerenchyma Mesophyll
Collenchyma phloem Secondary (strengthening (layer of
(supporting xylem tissue) photosynthetic
tissue) tissue)
Pith with stellate
parenchyma Vascular
Primary (star-shaped bundle
xylem packing
tissue)
Epidermis
(outer layer Xylem
of cells) Pith
Phloem

Epidermis
Pith (outer layer Sclerenchyma
cavity of cells) with thick (strengthening
Cortex cuticle (waterproof tissue)
(layer between covering)
epidermis and DEADNETTLE RUSH
vascular tissue) (Lamium sp.) (Juncus sp.)
Parenchyma Vascular bundle
Epidermis (packing tissue) with (xylem, phloem,
(outer layer of cells) bundles of sclerenchyma and sclerenchyma
Phloem (strengthening tissue) fibers)
Vascular
Xylem tissue
Lacuna
(air space) Epidermis
(outer layer
of cells)

Pith



Cortex
(layer between Mesophyll
epidermis and (layer of Cortex
vascular tissue) Endodermis photosynthetic (layer between
(inner layer tissue) epidermis and
MARE’S TAIL of cortex) COCONUT PALM vascular tissue)
(Hippuris vulgaris) (Cocos nucifera)
135

PLANTS
SIMPLE LEAF SHAPES
Leaves Subacute apex Acuminate
apex

LEAVES ARE THE MAIN SITES OF PHOTOSYNTHESIS (see pp.
138-139) and transpiration (water loss by evaporation)
in plants. A typical leaf consists of a thin, flat lamina
(blade) supported by a network of veins; a petiole (leaf
stalk); and a leaf base, where the petiole joins the
stem. Leaves can be classified as simple, in which
CHECKERBLOOM the lamina is a single unit, or compound, in Entire Entire
(Sidalcea malviflora) margin margin
which the lamina is divided into separate
leaflets. Compound leaves may be pinnate, with pinnae (leaflets)
on both sides of a rachis (main axis), or palmate, with leaflets
arising from a single point at the tip of the petiole. Leaves can
be classified further by the overall shape of the lamina, and
by the shape of the lamina’s Cuneate
base Cordate
apex, margin, and base. Apex
base
GENERAL LEAF PANDURIFORM LANCEOLATE
FEATURES Croton Sea buckthorn
(Codiaeum variegatum) (Hippophae rhamnoides)


COMPOUND LEAF SHAPES
Terminal
pinna
(leaflet)
Midrib
Lamina
(blade)
Emarginate
apex
Margin
Rachis
(main axis of
pinnate leaf)


Pinna
(leaflet)
Lateral
vein
Petiolule
(lea flet
stalk)


Lamina base
Petiole (leaf stalk) Petiole
(leaf stalk)
Leaf base

Sweet chestnut ODD PINNATE
(Castanea sativa) False acacia
(Robinia pseudoacacia)

136

LEAVES

Subacute Acuminate Subacute Acuminate
apex apex apex Mucronate apex
apex
Entire
margin
Entire Serrulate
margin margin



Cuneate base
ELLIPTIC ORBICULAR Entire
Fig Camellia margin
(Ficus sp.) (Camellia japonica)
Acute apex Cuspidate apex
Entire
margin Entire
Variegated margin
Cuneate lamina
base
(blade) Entire
margin
Cuneate base
Truncate
Cordate base base
OBOVATE RHOMBOID PALMATELY LOBED DELTOID LINEAR
Tupelo Persian ivy Common ivy Persian ivy Iris
(Nyssa sylvatica) (Hedera colchica (Hedera helix) (Hedera colchica) (Iris lazica)
‘Sulfur Heart’)
Pinnule
(leaflet of
Pinna pinna)
Pinna Leaflet (leaflet)
(leaflet)
Petiolule
(leaflet
stalk)
Rachis
(main axis of
pinnate leaf)
Rachis
(main axis of
pinnate leaf)
Petiole Rachilla
Petiole (leaf stalk) Petiole (secondary
(leaf stalk) (leaf stalk)
axis of
EVEN PINNATE DIGITATE BIPINNATE pinnate leaf)
Black walnut Horse chestnut Honey locust
(Juglans nigra) (Aesculus parviflora) (Gleditsia triacanthos)
Pinnule
(leaflet of
pinna) Pinna
(leaflet)
Leaflet Leaflet Rachilla
(secondary axis Rachis
of pinnate leaf) (main axis
oj pinnate
Rachis leaf)

Petiolule
(leaflet stalk)
Petiole Petiole
Petiole (leaf stalk) (leaf stalk)
BITERNATE (leaf stalk) TRIFOLIATE TRIPINNATE
Clematis Laburnum Meadow rue
(Clematis sp.) (Laburnum x watereri) (Thalictrum delavayi)

137

PLANTS

Photosynthesis MICROGRAPH OF LEAF
Lily (Lilium sp.)


PHOTOSYNTHESIS IS THE PROCESS by which plants make their food
using sunlight, water, and carbon dioxide. It takes place inside special
structures in leaf cells called chloroplasts. The chloroplasts contain
chlorophyll, a green pigment that absorbs energy from sunlight.
During photosynthesis, the absorbed energy is used to join together
carbon dioxide and water to form the sugar glucose, which is the
energy source for the whole plant; oxygen, a waste product, is
released into the air. Leaves are the main sites of photosynthesis,
and have various adaptations for that purpose: flat laminae (blades)
provide a large surface for absorbing sunlight; stomata (pores) in the
lower surface of the laminae allow gases (carbon dioxide and oxygen)
to pass into and out of the leaves; and an extensive network of veins Stoma Guard cell Lower
brings water into the leaves and transports the glucose produced by (pore) (controls surface of
photosynthesis to the rest of the plant. opening lamina
and closing (blade)
of stoma)
THE PROCESS OF PHOTOSYNTHESIS
Glucose molecule
Sunlight, which is absorbed
Oxygen Carbon Hydrogen Glucose is a high-energy by chloroplasts in the leaf,
atom atom atom product of photosynthesis. provides the energy for
It travels to all parts of the photosynthesis
plant through the phloem
The leaf is the main site of
photosynthesis. Its broad,
thin lamina (blade) is an
adaptation for this process













Hydrogen atom
Oxygen atom Water
molecule
Hydrogen atom



Oxygen atom
Oxygen
Carbon dioxide Carbon atom
atom
molecule Oxygen
Oxygen atom
Oxygen molecule
Water, a raw material atom
in the soil, travels to the Carbon dioxide, a raw Oxygen, a waste product
leaf from the roots via material in the air, enters of photosynthesis, leaves
the xylem the leaf through stomata the leaf through stomata
on the lower surface of the on the lower surface of
lamina (blade) the lamina (blade)
138

PHOTOSYNTHESIS
CROSS-SECTION THROUGH LEAF
Christmas rose
(Helleborus niger) Cuticle (waterproof covering)

Upper (adaxial)
Cell wall
epidermis (outer
layer of cells)
Cytoplasm
Vacuole
Chloroplast
Palisade mesophyll (photosynthetic
(tightly packed layer organelle)
of photosynthetic
tissue) Nucleus
Intercellular
space

Sclerenchyma
(strengthening
tissue)
Xylem (tissue
that transports
water and
mineral salts)
Spongy mesophyll
(loosely packed layer Phloem (tissue
of photosynthetic that transports
tissue) sugars and
other nutrients)
Vein




Lower (abaxial)
epidermis (outer
layer of cells) Parenchyma
(packing
Guard cell tissue)
(controls opening Stoma
and closing of (pore) Substomatal
stoma) chamber
INTERNAL VIEW OF CHLOROPLAST
Lamella
Granum (membrane of Thylakoid
(stack of thylakoids that thylakoid) (flat sac of
hold chlorophyll granum)
molecules in position)
Deoxyribonucleic
Stroma acid (DNA)
(watery matrix) strand

Outer Starch grain
Chloroplast membrane
envelope
Inner
membrane

Stroma thylakoid
Ribosome (link between grana)
(site of protein
synthesis)


139

PLANTS

Flowers 1 Inner tepal Honey
(monocotyledonous
guide
petal)
Groove
FLOWERS ARE THE SITES OF SEXUAL REPRODUCTION in secreting
flowering plants. Their component parts are arranged nectar
Style
in whorls around the receptacle (tip of the flower stalk). Filament
The sepals (collectively called the calyx) are outermost;
typically small and green, they protect the developing
flower. The petals (collectively called the corolla) are
typically large and brightly colored; they are found inside
the sepals. In monocotyledonous flowers (see pp. 126-127), sepals
Outer tepal
and petals are indistinguishable; individually they are called tepals (monocotyledonous
Stigma
(collectively called the perianth). The petals surround the male sepal)
Anther
and female reproductive structures (androecium and gynoecium). EXTERNAL VIEW
The androecium consists of stamens (male organs); each stamen
is made up of a filament (stalk) and anther. The gynoecium
has one or more carpels (female organs); each carpel consists
of an ovary, style, and stigma. Some flowers (e.g., lily) occur Outer tepal
singly on a pedicel (flower stalk); others (e.g., elder, (monocotyledonous
sepal)
sunflower) are arranged in a group (inflorescence)
on a peduncle (inflorescence stalk).
A MONOCOTYLEDONOUS
FLOWER
Lily Inner tepal
(Lilium sp.) (monocotyledonous
Ovary petal)
Syncarpous
(fused carpels) Honey
gynoecium Stigma guide

Style
Tepal
scar
Anther
Stamen Receptacle
Filament
Ovary
wall Ovule
Pollen on
anther Pedicel
(flower
stalk)

Papilla
(fleshy hair)
Outer tepal Style Folded inner tepal
sheath (monocotyledonous petal)
Stigma Ovary
Receptacle
Pedicel
Anther (flower
stalk)
LONGITUDINAL SECTION Filament
THROUGH FLOWER BUD
140

FLOWERS 1



Posterior
Honey Posterior sepal
guide sepal Membranous
spur of Posterior
False anthers posterior sepal petal
Posterior attract pollinating
petal insects Anterior
petal
Lateral Bract
sepal (leaflike Anther
structure)
Anterior
petal Anterior
Anther sepal
Anterior
sepal
Bract
(leaflike Pedicel Pedicel
structure) (flower stalk) (flower stalk)
Lateral
EXTERNAL VIEW sepal
SIDE VIEW
A DICOTYLEDONOUS FLOWER
Larkspur
(Delphinium orientalis) Position
of nectary Posterior
petal

Membranous Anterior
spur petal

Posterior
sepal

Immature
spur of
posterior sepal
Androecium
Bract
(leaflike
structure) Ovary Sepal
sheath
Receptacle Carpel Style Filament
Stamen
Stigma Anther
Pedicel Pedicel
(flower stalk) Bract (flower
(leaflike stalk)
structure)
EXTERNAL VIEW
OF FLOWER BUD


Nectary
Membranous Ovary
spur Filament
Anther
Receptacle
Anterior Sepal
sepal Pedicel sheath
(flower stalk)

LONGITUDINAL SECTION THROUGH FLOWER BUD
141

PLANTS

Flowers 2 COMPOUND INFLORESCENCE
(CAPITULUM)
Sunflower
(Helianthus annulus)
Disk florets


Ray floret

Sterile ray floret to
attract pollinating
insects
Florets (small
Florets with
flowers) are grouped
anthers ready
Outer Two-lobed together to resemble
to shed pollen
fertilized stigma a single large flower
floret Inner, immature
Pollen
Style Anther florets
Corolla
tube
(fused
Pappus petals)
(modified Corolla tube (fused petals)
sepal) Ovary
Ovary
FLORETS FROM SUNFLOWER

Pollen
Anther Ray floret
Nectar Disk floret




Stigma
Style




Ovary
Corolla tube
(fused petals)
Pappus
(modified
Bract sepal)
(leaflike structure) Domed receptacle
(flattened top of
Hair inflorescence stalk)
Pith



Epidermis
(outer layer Peduncle
LONGITUDINAL SECTION THROUGH of cells) (inflorescence
SUNFLOWER INFLORESCENCE of peduncle stalk)
(inflorescence
stalk)

142

FLOWERS 2
ARRANGEMENT OF FLOWERS ON STEM


Spathe
(large bract)
to attract
Flower pollinating insects
Spadix (fleshy
axis) carrying
male and female
Bract flowers
(leaflike
structure)
Petal
Flower



Ovary



Peduncle
(inflorescence
Remains of tepals stalk)
(monocotyledonous Peduncle
Pedicel
petals and sepals) Peduncle (flower (inflorescence
(inflorescence stalk)
stalk) stalk)
INFLORESCENCE (SPIKE) INFLORESCENCE INFLORESCENCE (SPADIX)
Heliconia peruviana (COMPOUND UMBEL) Painter’s palette
Common elder (Anthurium andreanum)
Stigma
Anther (Sambucus nigra)
Stamen
Style
Filament
Flower
bud
Three-lobed Flower
stigma
Pedicel Inner tepal
(flower (monocotyledonous
stalk) petal)
Style
Bract
(leaflike
structure)

Filament
Ovary Stamen
Anther
Peduncle
(inflorescence Outer tepal
stalk) fused (monocotyledonous Corolla
to bract sepal)
Calyx
Pedicel Peduncle
(flower stalk) (inflorescence
stalk) Bract
SINGLE FLOWER (leaflike
Glory lily structure)
(Gloriosa superba) SINGLE
FLOWER
INFLORESCENCE
(DICHASIAL CYME) INFLORESCENCE
Common lime (SPHERICAL UMBEL)
(Tilia x europaea) Allium sp.


143

PLANTS

Pollination REPRODUCTIVE STRUCTURES IN
WIND-POLLINATED PLANT
Sweet chestnut
(Castanea saliva)
POLLINATION IS THE TRANSFER OF POLLEN (which contains
the male sex cells) from an anther (part of the male Flower bud Male
reproductive organ) to a stigma (part of the female Prominent stigma flower
reproductive organ). This process precedes fertilization protrudes from flower
(see pp. 146-147). Pollination may occur within the same Female
flower (self-pollination), or between flowers on separate flower
Peduncle
plants of the same species (cross-pollination). Part of male (inflorescence
Petiole catkin
In most plants, pollination is carried out either stalk)
(leaf stalk) (inflorescence
by insects (entomophilous pollination) or by the adapted for
wind (anemophilous pollination). Less commonly, Bract wind Filament
(leaflike pollination)
birds, bats, or water are the agents of pollination.
structure)
Insect-pollinated flowers are typically brightly
colored, scented, and produce Peduncle Anther
(inflorescence
nectar, on which insects stalk)
feed. Such flowers also Stigma
FEMALE MALE
tend to have patterns that
are visible only in ultraviolet REPRODUCTIVE STRUCTURES IN
INSECT-POLLINATED PLANTS
light, which many insects can
see but which humans cannot.
Endothecium
These features attract insects, (pollen sac wall)
which become covered with the
Style
sticky or hooked pollen grains
Pollen
when they visit one flower, Dehisced grain
and then transfer the pollen (split open)
pollen sac Anther
to the next flower they visit. Stamen
Wind-pollinated flowers are Filament
generally small, relatively
inconspicuous, and unscented. Boundary between
They produce large quantities two fused carpels
of light pollen grains that are (each carpel
consists of a stigma,
easily blown by the wind to style, and ovary)
other flowers. Calyx
Ovary (whorl of
sepals)
MICROGRAPHS OF MICROGRAPH OF CARPELS (FEMALE ORGANS) MICROGRAPH OF STAMENS (MALE ORGANS)
POLLEN GRAINS Yellow-wort Common centaury
Exine (outer coat of pollen (Blackstonia perfoliata) (Centaurium erythraea)
grain) Colpus Colpus
(furrow-shaped Exine
(furrow-shaped
aperture) (outer aperture)
coat of
pollen Exine
grain) (outer
coat of
pollen
Pore grain)
Exine Baculum
Pore (outer coat of (rod-shaped Equatorial
pollen grain) structure) furrow
EUROPEAN FIELD ELM JUSTICIA AUREA MEADOW CRANESBILL BOX-LEAVED MILKWORT
(Ulmus minor) (Geranium pratense) (Polygala chamaebuxus)
144

POLLINATION
INSECT POLLINATION OF MEADOW SAGE

Pollen grains attached
Immature, unreceptive to hairy abdomen
stigma
Sepal Long style curves
downward when Sepal
bee enters flower
Anther pushed on to
bee’s hairy abdomen
Mature, receptive
stigma touches bee’s
Labellum
Pollen grains from abdomen, picking Labellum
(lip) forming (lip) forming
landing stage anther stick to up pollen
bee’s abdomen landing stage
for bee
for bee
1. BEE VISITS FLOWER WITH MATURE 2. BEE FLIES TO 3. BEE VISITS FLOWER WHERE
ANTHERS BUT IMMATURE STIGMA OTHER FLOWERS THE ANTHERS HAVE WITHERED
AND THE STIGMA IS MATURE
SUNFLOWER UNDER NORMAL
AND ULTRAVIOLET LIGHT Petal ST. JOHN’S WORT
UNDER NORMAL AND
Ovary ULTRAVIOLET LIGHT
Central area of Filament Stigma
disk florets Stamen Honey guide
Anther directs insects
Ray floret to dark,
central part
NORMAL LIGHT of flower
NORMAL LIGHT
Paler, outer part
of ray floret
Darker, inner
part of ray floret

Insects attracted to
darkest, central part
of flower, which
contains nectaries,
anthers, and stigmas



Dark central area containing
nectaries, anthers, and stigmas
ULTRAVIOLET LIGHT
Colpus
(furrow-shaped
ULTRAVIOLET LIGHT Columella (small aperture)
Trilete mark column-shaped Exine
(development structure)
Exine (outer coat of
Pore (outer coat of scar) pollen grain)
pollen grain)




Tricolpate
Exine Exine (three colpae)
(outer coat of (outer coat of pollen grain
pollen grain) pollen grain)
MIMULOPSIS SOLMSII THESIUM ALPINIUM RUELLIA GRANDIFLORA CROSSANDRA NILOTICA

145

PLANTS

Fertilization DEVELOPMENT OF A SUCCULENT FRUIT
Blackberry
(Rubus fruticosus)

FERTILIZATION IS THE FUSION of male and female
gametes (sex cells) to produce a zygote (embryo). Petal
Following pollination (see pp. 144-145), the pollen
Filament
grains that contain the male gametes are on Stamen
the stigma, some distance from the female Anther
gamete (ovum) inside the ovule. To enable the
gametes to meet, the pollen grain germinates
and produces a pollen tube, which grows Ovary
down and enters the embryo sac (the inner Carpel Stigma
part of the ovule that contains the ovum).
Style 1. FLOWER IN FULL BLOOM
Two male gametes, traveling at the tip of the
ATTRACTS POLLINATORS
pollen tube, enter the embryo sac. One gamete
fuses with the ovum to produce a zygote that
Abortive
will develop into an embryo plant. The other Remains of
Endocarp seed
male gamete fuses with two polar nuclei to (inner layer of style
produce the endosperm, which acts as a food pericarp)
Carpel
supply for the developing embryo. Fertilization
Mesocarp
also initiates other changes: the integument (outer (middle Receptacle
part of ovule) forms a testa (seed coat) around the layer of
pericarp)
embryo and endosperm; the petals fall off; the stigma
and style wither; and the ovary wall forms a layer Exocarp Remains
(called the pericarp) around the seed. Together, the (outer of stamen
layer of
pericarp and seed form the fruit, which may be pericarp)
succulent (see pp. 148-149) or dry (see pp. 150-151).
Sepal Pedicel
In some species (e.g., blackberry), apomixis can
BANANA (flower
(Musa ‘lacatan’) occur: the seed develops without fertilization of stalk)
the ovum by a male gamete but endosperm formation and fruit
4. PERICARP FORMS
development take place as in other species.
FLESH, SKIN, AND A HARD INNER
LAYER (SHOWN IN CROSS-SECTION)
Drupelet
Exocarp Exocarp
(outer layer of (outer layer of Exocarp
pericarp) pericarp) (outer layer
of pericarp) Drupelet
Carpel Remains
of style Remains
of style
Remains
of style
Remains
of stamen Remains
of stamen
Remains Remains
of sepal of sepal Remains
of sepal Remains
of stamen
Pedicel Pedicel Pedicel
(flower (flower (flower
stalk) stalk) stalk)
7. MESOCARP (FLESHY PART OF PERICARP) 8. CARPELS MATURE INTO DRUPELETS 9. MESOCARP OF DRUPELET BECOMES
OF EACH CARPEL STARTS TO (SMALL FLESHY FRUITS WITH SINGLE SEEDS DARKER AND SWEETER
CHANGE COLOR SURROUNDED BY HARD ENDOCARP)
146

FER TILIZATION
THE PROCESS OF FERTILIZATION
Anther Stamen Remains of stigma Generative nucleus
Filament and style (divides to form two Pollen tube
Carpel
male gametes) nucleus
Ovary
Pollen grain Pore
Anther lands on stigma
Stamen
Filament
Surface of stigma
Pollen
tube
Sepal
Male gamete Pollen
Pedicel Prickle (sex cell) tube
(flower Sepal nucleus
stalk) Pedicel POLLEN GRAIN GERMINATES
(flower stalk)
Pollen grain Stigma
2. FERTILIZATION HAS TAKEN 3. OVARIES BEGIN TO SWELL;
PLACE; PETALS FALL OFF STAMENS WITHER AND DIE Style
Pollen tube
Polar nucleus
Exocarp Remains Antipodal
(outer layer of style cell
Exocarp Remains of pericarp)
(outer of style
layer of Carpel Ovary Ovule
pericarp) Carpel
Micropyle
Remains of (entrance
stamen to ovule)
Remains Embryo sac
of stamen Ovum Male gamete
(female gamete) Receptacle
Sepal
MALE GAMETES TRAVEL TO
EMBRYO SAC
Sepal Pedicel Pedicel Nucellus
(flower stalk) (flower stalk) (layer surrounding Antipodal cell
embryo sac)
Integument
(outer part
5. CARPELS EXPAND AND BECOME 6. CARPELS EXPAND of ovule)
MORE FLESHY FURTHER 2nd male gamete
fuses with polar 1st male
Exocarp nuclei to form gamete fuses
(outer layer Remains Remains of style endosperm nucleus with ovum to
of pericarp) of style form embryo
Synergid nucleus
(disappears after Pollen tube reaches
Drupelet fertilization) ovum via micropyle
FERTILIZATION
Drupelet
Exocarp
(outer Style and
layer of stigma wither
pericarp)
Testa
Remains Endosperm (seed coat)
of stamen (food store)
Cotyledon
Remains
Remains of stamen Pericarp (seed leaf)
of sepal (maturing Plumule
Pedicel Pedicel ovary wall)
(embryonic
(flower (flower Remains shoot)
stalk) stalk) of sepal
Embryo plant Radicle
(embryonic
10. DRUPELETS (COLLECTIVELY 11. DRUPELETS RIPEN FULLY root)
AN AGGREGATE FRUIT) EXPAND
DEVELOPMENT OF EMBRYO
147

PLANTS

Succulent fruits HESPERIDIUM (A TYPE OF BERRY)
Lemon
(Citrus limon)
Pedicel
Endocarp (flower stalk)
Pedicel
A FRUIT IS A FULLY DEVELOPED and ripened ovary (flower Mesocarp Exocarp
(seed-producing part of a plant’s female reproductive stalk)
organs). Fruits may be succulent or dry
(see pp. 150-151). Succulent fruits are
fleshy and brightly colored, making
them attractive to animals, which
eat them and so disperse the seeds Seed
Leathery
away from the parent plant. The
exocarp Vesicle
wall (pericarp) of a succulent fruit Oil (juice
has three layers: an outer exocarp, gland sac)
a middle mesocarp, and an inner
Remains Remains Placenta
endocarp. These three layers vary of style of style
in thickness and texture in different
EXTERNAL VIEW LONGITUDINAL SECTION
types of fruits and may blend into OF FRUIT THROUGH FRUIT
each other. Succulent fruits can be
classed as simple (derived from Embryo Seed
Hilum Carpel
one ovary) or compound (derived
BERRY (point of wall
Cocoa from several ovaries). Simple attachment
(Theobroma cacao) to ovary) Carpel
succulent fruits include berries,
which typically have many seeds, and drupes, which
typically have a single stone or pit (e.g., cherry Testa
(seed Placenta
and peach). Compound succulent fruits include coat) Cotyledon
aggregate fruits, which are formed from many (seed leaf)
ovaries in one flower, and multiple fruits, which EXTERNAL VIEW AND CROSS-SECTION
SECTION THROUGH SEED THROUGH FRUIT
develop from the ovaries of many flowers. Some
fruits, known as false fruits or pseudocarps, develop
from parts of the flower in addition to the ovaries. SYCONIUM (A TYPE OF FALSE FRUIT)
Fig Remains
For example, the flesh of the apple is formed (Ficus carica) of female Fleshy infolded
from the receptacle (the upper end of the flowers receptacle
flower stalk). Peduncle Pip (seed Remains
(inflorescence surrounded of male
stalk) by endocarp) flowers

FRUIT WITH FLESHY ARIL
Lychee
(Litchi chinensis)
Pedicel Pedicel
(flower stalk) (flower stalk) Pore closed
by scales
Skin
EXTERNAL VIEW LONGITUDINAL SECTION
Seed OF FRUIT THROUGH FRUIT
Remains
of style Endocarp
EXTERNAL VIEW AND
Aril (fleshy SECTION THROUGH PIT
outgrowth Drupelet
from seed Pit
stalk)
Endocarp Cotyledon
Pedicel
Pericarp Pericarp (flower (seed leaf)
(fruit wall) (fruit wall) stalk) Embryo
Testa
EXTERNAL VIEW LONGITUDINAL SECTION REMAINS OF A SINGLE (seed coat)
OF FRUIT THROUGH FRUIT FEMALE FLOWER
148