Transcript Plant Classification

Kingdom
Plantae
National Geographic Plants
Kingdom Plantae
• What are plants?
• most are autotrophs
• eukaryotic
• have cell walls containing cellulose
• mostly land dwelling organisms
• they are the foundations of almost all
ecosystems.
Plants
Non-flowering
Sporebearing
No
roots
Mosses
with
roots
Ferns
Naked
seeds
Gymnosperms
Flowering
1 seedleaf
Monocots
2 seedleaves
Dicots
Evolution of Plants
• ancestors of modern day plants were aquatic organism
similar to green algae.
• to grow on land, plants have developed:
• an embryo – reproductive structure which develops
directly into a plant.
• ability to stand upright and reach for the sun
• tissues to transport water, nutrients and wastes.
• strategies to reduce water loss
• strategies to disperse seeds without relying on water
currents.
• flowering plants are the youngest in plant evolution.
Alternation of Generations
• most plants have a life cycle that alternates between diploid
and haploid forms.
• diploid (2 sets of chromosomes – 1 from each parent)
• haploid (1 chromosome set)
Classification of Plants:
• there are 5 major groups of plants:
• green algae
• mosses and relatives
• ferns and relatives
• seed plants
• flowering plants
1. Green Algae – modern relatives of plant ancestors
• many species are found in shallow fresh water – edges of
ponds
2. Mosses and Relatives – seedless non-vascular plants
• (Bryophytes)
• grow close to the ground in damp locations where can easily
obtain water.
• no seeds or stems – no rigid support structures in cell walls,
so can’t grow tall.
• non-vascular – can’t transport water or nutrients within.
• male and female gametes are produced in separate
reproductive structures - sperm have flagella and swim
through water to the eggs.
Spore-producing capsule
Mosses
3. Ferns and Relatives –
seedless vascular plants
•have vascular structures to
carry water.
• gives advantage: can grow
taller – reach the sunlight
•vascular structures (veins)
connect shoots above ground to
roots below
• seedless: reproduce much like
mosses – sperm swims to egg
on a film of water on the
underside of the plant.
4. Gymnosperms – seed plants
• conifers (pine, fir, cedar, ginko)
• ‘naked seeds’ – not protected or
enclosed in an ovary.
•seeds are plant embryos packaged in
a protective coat along with a food
supply.
• pollen grains are small male
gametophytes that contains cells that
develop into sperm.
• wind carries the pollen grains to
female cones – where eggs develop.
5. Angiosperms – flowering plants
• reproductive structures are flowers
• 2 groups: monocots and dicots
• ovaries within flowers completely protect the seeds.
• gametophytes of angiosperms develop within the flowers
• flowers have many adaptations to disperse pollen and seeds.
• insects, animals, birds (and wind) all transfer pollen from one
flower to another.
• once pollination occurs the ovary develops into a fruit – the
ripened ovary of a flower.
• fruits are a good way to disperse seeds:
• if ingested, the seed survives and drops elsewhere
• burrs stick to animal fur.
• maple keys are suited to wind dispersal
• coconuts are well suited to water dispersal
Flowering
Plants
Monocotyledons
Dicotyledons
MONOCOTS vs. DICOTS
MONOCOTS
10 % of monocots (one seed
leaf) have a woody stem
(rigid). Examples include
bamboo and palm trees.
MONOCOTS
Most have a herbaceous
stem (soft, fleshy).
These include lilies, tulips,
orchids, etc.
DICOTS
Dicots are deciduous trees.
They are considered to be
“hardwood” and also
provide a large amount of
money to Canada in the
lumber industry.
DICOTS
Dicots are often used to make furniture, hockey sticks, and
provide fuel for heating purposes.
A typical salad contains many dicots (lettuce, tomatoes,
radishes).