Perfectly Proper Plants

Alternation of Generations

Alternation of Generations All plants alternate between a multicellular haploid generation (gametophyte because it produces gametes) and multicellular diploid generation (sporophyte because it produces spores)

Types of Plants Bryophytes Mosses, liverworts, hornworts Gametophyte is the dominant generation! No real vascular tissue to conduct water and nutrients Few cell layers thick, keeps them close to water and minerals Sporophyte releases bzillions of spores (but need to stay attached to the gametophyte)

Life Cycle of a Moss

Vascular Tissue (except Bryophytes) Xylem Tube-shaped dead cells Most Contain Tracheids - Bring water and minerals UP from roots

Vascular Tissue (except Bryophytes) Phloem Living tissue Nutrient-conducting cells arranged in tubes Distribute sugars, amino acids, and organic stuff THROUGH the plant

Roots Absorb water and nutrients from the soil Anchor vascular plants so the shoot can grow taller

Leaves Increase the surface area of the plant body Primary location for photosynthesis Can be Microphylls – small, spine shaped Megaphylls – highly branched with higher levels of photosynthesis

Seedless Vascular Plants Pterophytes - Ferns! Sporophyte is the larger and more complex!! (Gametophyte is fragile and small) Sperm cells of ferns have flagella and need to swim through a film of water to reach eggs (just like bryophytes) Common in damp habitats

Fern Life Cycle (592)

Vascular (seed) plants Seeds Multi-cellular (more complex than a spore) Sporophyte embryo packaged with a food supply in a protective coat Microsporangia produce male gametophyte Megasporangia produce female gametophyte Female gametophyte stays in parent sporophyte When fertilized, the whole ovule (ovary) becomes the seed

Gymnosperms - Coniferphyta Cone-Bearing Plants “naked seeds” No enclosed chamber for the ovary. Ovules and seeds develop on special leaves called sporophylls

Life Cycle of Gymnosperm (605)

Angiosperms (Flowering) Flower: Sex parts Stamen: Male repro organs (microspores - anther, filament) Carpels: Female repro organs (megaspores - stigma, style, ovary) Fruit: Mature ovary Thickened wall of ovary to protect the seeds and help disperse them

Structure of a Flower (608)

Life Cycle of Angiosperm (611)

Monocot vs Dicot

Monocots vs Dicot