Topic 6.3 Support, growth and stability in plants

• The main support for plants is the stem and
the root.

• The plant stem supports its own weight and
also the weight of leaves, flowers and fruits.

• The root provides support to the plant by
gripping the soil.

Terrestrial Plants

• Terrestrial plants can be divided into
a) Woody plants : e.g. rambutan tree, angsana tree ……..
b) Herbaceous plants (non-woody):
e.g. cucumber plant,

balsam plant……

Terrestrial Plants

• Woody plants have hard, strong, tough woody tissue for
support.

• Non-woody plants depends on the turgidity of the cells for
support.

Woody plants have buttress roots

Woody plants have prop roots

Woody plants have stilt roots

Tendrils in non-woody plants

Clasping roots of non-woody plants

Aquatic Plants

• Aquatic plants do not have woody tissue for support, they
obtain their main support from the water buoyancy force.

• Aquatic plants also have stems and leaves that have
aerenchyma tissue.

Water hyacinth Aquatic Plants

Aerenchyma
tissue in the stem



• The plant stability is influenced by the centre of gravity and its
base area.

• The lower the centre of gravity, the more stable the plant is.
• The broader the base area, the more stable the plant is.

• Experiment 6.2 (p.137)