The 3 Main Criteria for determining if an organism is a plant:

•Multicellular (have many cells)•Autotrophic (make their own food)

•Eukaryotic (have membrane bound organelles & nucleus)

•In addition, all plants have an alternation of generation life cycle (more on this later)

Follow a similar path as Animals:

Microscopic Macroscopic Unicellular Multicellular Simple Complex Water Land Diffusion Vascular

System(transp/supprt) No seeds Seeds

The first plants appeared 600 mya - Proterozoic era Probably arose from photosynthetic protists Algae are still the most abundant/widespread

plants Algae provide 90% of earth’s biomass and oxygen Green algae are the likely ancestors of land plants First land plants arose during the Devonian-

200mya Gymnosperms arose in Pennsylvannian Angiosperms arose in the Jurassic

Algae: strictly aquatic; Bryophytes (mosses and liverworts): first land

plants; small and tied to water for reproduction Ferns: 1st land plants to have vascular tissue &

thus can grow tall; tied to moisture for reproduction

Gymnosperms (conifers): have sophisticated vascular tissue; inhabits all habitats; seeds are naked

Angiosperms (flowering plants): same as G; seeds are enclosed & store food; great dispersal ability

A type of life cycle found in plants that alternates between 2 different versions of adult plants – the sporophyte and the gametophyte plant

The lifecycle repeats, with sporophyte plants reproducing gametophyte plants and visa versa

The Sporophyte plant produces spores, which after released, will germinate and each spore will grow into a new plant (the gametophyte)

The Gametophyte plant produces gametes, (eggs and sperm). After an egg and sperm unite (fertilization), the zygote will germinate and grow into a new plant (the sporophyte)

Sporophyte

spores

gametophyte

gametes

Sporophytes & Gametophytes (attached)

Gametophytes

Sporophytes

rhizoids