Kingdom

PlantaeNational 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.

Non-flowering

Plants

Flowering

Spore-bearing

Naked seeds

No roots

with roots

Mosses Ferns

Gymnosperms

1 seed-leaf

2 seed-leaves

Monocots 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.

MossesSpore-producing capsule

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

MonocotyledonsMonocotyledons DicotyledonsDicotyledons

Flowering Plants

MONOCOTS vs. DICOTS

MONOCOTS10 % of monocots (one

seed leaf) have a woody stem (rigid). Examples include bamboo and palm trees.

MONOCOTSMost have a herbaceous

stem (soft, fleshy).

These include lilies, tulips, orchids, etc.

DICOTSDicots are deciduous

trees. They are considered to be

“hardwood” and also provide a large amount of money to Canada in the lumber industry.

DICOTSDicots are often used to make furniture, hockey sticks,

and provide fuel for heating purposes.

A typical salad contains many dicots (lettuce, tomatoes, radishes).