PLANT
DIVERSITY
PLANT CLASSIFICATION
• The plant kingdom has been classified into four major
groups:
1.
2.
3.
4.
Bryophytes (Nonvascular plants)
Pterophytes (First vascular plant)
Gymnosperm (Cone-bearing plants)
Angiosperm (Flowering plants)
• Plants are classified by the presence or absence of:
• vascular tissue (xylem and phloem)
• true leaves and roots
• dependence on water for reproduction
• seeds or spores
• cones or flowers
• fruit
Bryophytes –
Nonvascular
plants
• Poorly adapted to life on land
• Live in moist, shady places growing on
rocks, trees and soil.
• CHARACTERISTICS:
• No vascular tissue  unable to transport
water; absorbs water through their entire
body.
• No true roots, stems or leaves  have
rhizoids to anchor the plant.
• No cuticle
• No strengthening tissue
• Homosporous
• Dependent on water for reproduction
• Alternation of generation:
• Gametophyte (haploid) is dominant; can
photosynthetic; produce gametes
• Sporophyte (diploid) is dependent on
gametophyte generation.
Vascular Plants
What are the adaptations needed for
terrestrial life?
What are the main differences
between nonvascular and vascular
plants?
• Prevent desiccation  cuticle and
stomata decrease water loss.
• Vascular plants:
• To aid nourishment the following was
needed:
• Roots
• Vascular tissue
• Supporting tissue
• To aid reproduction the development of
spores and seeds was needed.
• possess vascular tissue
(xylem and phloem)
• Sporophyte generation is
the largest generation and
more conspicuous
generation
Pterophytes –
Seedless vascular
plants
• Pterophytes are more evolved for terrestrial life
than Bryophytes.
• Characteristics:
• Have roots, stems and leaves:
o
o
•
•
•
•
•
•
•
•
Roots grow out the horizontal stem (rhizome)
Leaves are deeply divided
Have vascular tissue
Thin cuticle and stomata
Reproduces by the means of spores
Produce motile male gametes which like moss rely
on water for fertilization.
Have an independent sporophyte generation which
develops from the gametophyte generation.
No flowers, seeds or cones
New leaves are coiled up
Sporangia are found on the undersurface of the
leaves
Why can ferns grow
in drier places than
mosses?
• Ferns have proper roots with water conducting
tissue, xylem, for the absorption and transport
of water from the soil.
• Ferns have a waxy cuticle which helps prevent
the loss of water from the leaves.
LEARNING ACTIVITY 3
Seedless plants; pg. 254
Seed-bearing plants
• Two major groups:
1. Cone-bearing plants (Gymnosperm)
2. Flowering plants (Angiosperm)
• WHAT SEED-BEARING PLANTS SHARE WITH
FERNS:
• Plant body with true roots, stems and leaves
• Presence of vascular tissue
• A dominant and independent sporophyte generation
Seed-bearing
plants
• SEED PLANTS DIFFER FROM
MOSSES AND FERNS:
• Gametophyte generation has
been reduced in size and are
now found in seeds.
• Gametes not dependent on
water for fertilisation
• Spores of seeds are either male
or female  heterosporous
• Megapsore  female spore
• Microspore  male spore
MAJOR
EVOLUTIONARY
ADVANCEMENT OF
SEED PLANTS
• The plant body is more complexed – allows plants to
grow taller; enabling them to maximum amount of
sunlight.
• Pollen grains are produced form microspores
• Microspores produce male gametes (sperm
cells)
• Pollen grains are transferred to the macro spore
(female gamete)with the help of wind, animals,
insects and water)
• Pollen grain develops a pollen tube through
which the non-motile male gamete are carried
directly to the female gamete  this has
MAJOR EVOLUTIONARY
ADVANCEMENT OF
SEED PLANTS
• Resistant seeds are produced
• Allows a plant embryo to lie dormant until
conditions becomes suitable for germination
• Has food for the embryo’s needs in early
growth and development
Gymnosperm –
Cone-bearing
plants
• CONIFERS – Yellow wood
• Evergreen trees and have long
narrow leaves
• Male and Female trees
• The male cones are adapted for wind
dispersal  light and sticky
• Have no Flowers or fruit
• Produce naked seeds
FLOWERING
PLANTS
• Angiosperms evolved much later
than the gymnosperms
• Most advanced type of plants
• They are vascular, seed-bearing
plants that have flowers and fruit
TWO GROUPS:
MONOCOTYLEDONS &
DICOTYLEDONS