How Did Plants Evolve?

Scientists believe that plants evolved from an ancestor of green algae (a member of Kingdom Protista). These early plants were similar to today’s mosses (shown through fossil evidence) Were dependent on water for reproduction and to avoid drying out.

The Move To Land… The advantage of life on land… More sunlight More CO2 More nutrients The disadvantage? Water Loss/Drying Out! So, what adaptations did plants develop in order to thrive on land?

Adaptations: 1: The Cuticle A waxy covering that prevents water loss 2: Vascular Tissue Not every part of a plant is touching water, so tubes transport materials up and down. Xylem: Water up from the roots Phloem: Sugars down from the leaves. 3: Seeds Instead of Spores Spores need water to reproduce Seeds provide an embryo with the food and protection needed for a dry environment.

The Plant “Family Tree” Cuticle Vascular Tissue Seeds Fruit & Flowers Green Algae Ancestor Bryophytes Ferns Gymnosperms Angiosperms The Plant “Family Tree”

The Bryophytes (Seedless Non-Vascular Plants) Liverwort Hornwort Cuticle? Yes Vascular Tissue? No So…Stays close to the ground, near water Seeds? So…reproduces with spores, must be near water Examples? Mosses Liverworts Hornworts

Life Cycle of Moss

The Plant “Family Tree” Cuticle Vascular Tissue Seeds Fruit & Flowers Green Algae Ancestor Bryophytes Ferns Gymnosperms Angiosperms The Plant “Family Tree”

The Ferns (Seedless Vascular Plants) Cuticle? Yes Vascular Tissue? Seeds? No So…reproduces with spores, must be near water Examples? Ferns Horsetail Equisetum

Life Cycle of Fern

The Plant “Family Tree” Cuticle Vascular Tissue Seeds Fruit & Flowers Green Algae Ancestor Bryophytes Ferns Gymnosperms Angiosperms The Plant “Family Tree”

The Gymnosperms (Vascular Seed Plants) Cuticle? Yes Vascular Tissue? Yes (but leaves are reduced to needles to prevent water loss) Seeds? But…they are naked! Males & Female Cones Examples? Pine Spruce Gingko Male & Female cone

Gymnosperm Life cycle

The Plant “Family Tree” Cuticle Vascular Tissue Seeds Fruit & Flowers Green Algae Ancestor Bryophytes Ferns Gymnosperms Angiosperms The Plant “Family Tree”

The Angiosperms (Vascular Seed Plants) Stinking Corpse Lily – p 591 Cuticle? Yes Vascular Tissue? Seeds? Flowers & fruit protect and help disperse! Examples? Flowering Plants Grass Corn

Task: you need to find a way to survive with your feet permanently anchored in cement You CAN’T: Hide from predators Seek a mate Walk to water or food Change your habitat You HAVE to: Get necessary nutrients Get water & oxygen Reproduce (your mate may be miles away) Deal with changes in your environment (i.e. dry, wet, hot, cold, dark, light, etc..)