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Plants – Characteristics and
Function
Evolution of Plants
• Scientists believe that
terrestrial plants evolved
from green algae as both
show the following
similarities:
• Use starch as their
primary food reserve
• Have cellulose in their
cell walls
• Use chlorophyll a and b
for photosynthesis
Evolution of Plants
• In order to adapt to
the drier, terrestrial
environment, plants
developed specialized
structures to avoid
water loss (bark),
obtain nutrients
(roots, stems, leaves)
and reproduce/grow
(spores, seeds,
flowers)
Evolution of Plants
• The first plants were nonvascular, like moss, that
depended on osmosis
and diffusion to get water
and nutrients.
• Vascular plants evolved
which had specialized
cells used for the
transport of water (Xylem)
and nutrients (Phloem),
called vascular tissue.
Plant Tissue
•
Like animals, plants are made up of four types of tissue:
1.
Meristematic tissue is where cell growth occurs.
2.
Dermal tissue is the outermost cell layer of the plant. It is used for
protection and to prevent water loss.
Plant Tissue
3. Ground tissue is the inner cell layers of the plant that
is not vascular tissue. This is where nutrients are
stored and where the plant does photosynthesis.
4. Vascular tissue are the cells involved in transporting
water and nutrients through the plant.
Main types of vascular plants
• Gymnosperms: mainly
coniferous trees, seeds
appear on cones, make
up the majority of
Canadian forests, termed
‘softwood’ by lumber
companies and provide
most of the money
earned by Canada’s
forestry industry.
Main Types of Vascular Plants
• Angiosperms: many
more species than
gymnosperms, live in
a wider variety of
habitats, use flowers
to reproduce and
encase the seed in a
‘fruit’, divided into
monocots and dicots.
Monocots and Dicots
Criterion
Monocots
Dicots
Seed Leaves
1
2
Veins in
Leaves
Vascular
Bundles in
Stems
Flower Parts
Parallel
Netlike
Scattered
Arranged in a
ring
Petals are
multiples of 3
Petals are
multiples of 4 or
5
Monocots
• Only about 10% have
a woody stem
(bamboo and palm
trees).
• Most have a
herbaceous stem
which is soft and
fleshy (grass, tulips,
etc…)
• Rice, corn, wheat,
onions, carrots, …
Dicots
• Deciduous trees are dicots.
• Termed ‘hardwood’ and make up a good portion of the lumber
industry in Canada.
• Other dicots: beans, potatoes, most wildflowers and salad
ingredients (tomatoes, lettuce, cabbage, radishes…)