The Plants 293,000 species. made of eukaryotic cells; all plants are multicellular; most are large with distinct tissues (dermal, vascular & ground tissues) and organs; some of the major organs are roots, stems, leaves, flowers and fruits; they are nonmotile, usually anchored in the ground but some attach to other plants; have fairly thick, rigid cell walls of cellulose giving most individual cells a square or rectangular shape; almost all are green; contain the pigment chlorophyll inside organelles called chloroplasts that carry out photosynthesis. Plants are classified into 4 major groups.

Mosses & Allies (~23,600 species) most ancient plants and simplest surviving plants, most are small, inconspicuous and live in moist habitats; generally poorly adapted to life on land: no vascular tissue, no true organs; distinctive alternation of generations with asexual sporophyte and sexual gametophyte producing sperm and egg. Mosses (Phylum Bryophyta) 16,000 species generally poorly adapted to land, live in dense beds on moist soil, rocks or bark; each individual plant has tiny rootlike rhizoids for attachment (not to absorb nutrients for the plant); slender stemlike structure bears leaflike blades; no vascular tissue, therefore no true roots stems or leaves; gametophyte is the dominant form: Liverworts (Phylum Hepaticophyta) 9,000 species small inconspicuous plants; grow on moist soil, rocks, stumps and tree bark; especially common in coniferous forests; gametophyte body is flattened, branching thallus with umbrella shaped clusters of antheridia or archegonia; life cycle is similar to mosses Hornworts (Phylum Anthocerotophyta) 100 species gametophyte superficially resembles liverwort thallus; found in “disturbed” habitats (eg. fallow fields, roadsides); after fertilization a spikelike “horn” grows out of thallus

Ferns & Allies (11,000 species) mostly terrestrial, a few are aquatic; in temperate regions they typically inhabit swamps and moist areas; have true vascular tissueshave true roots, stems and leaves; still require water for sexual reproduction; sporophyte and gametophyte are completely separate plants

Ferns (Phylum Pterophyta) 10,000 species mostly terrestrial, a few are aquatic; range from tropics to arctic but most are tropical epiphytes; spore production occurs on underside of leaf in clusters of sporangia called sori spores germinate into a gametophyte called a prothallium Whisk Ferns (Phylum Psilotophyta) 12 species mainly tropical; simple dichotomously branching stems with underground rhizome; small scalelike leaves; distinctive sporangia producing spores which germinate into prothallium. Horsetails (Phylum Sphenophyta) 40 species today consists of a single genus; grow mostly in wet marshy habitats; up to 4 feet tall; on every continent except Australia; hollow jointed stems are impregnated with silica giving stem a gritty texture (=scouring rushes); at each joint is whorl of small nonfunctional leaves (megaphylls) Club Mosses (Phylum Lycophyta) 501 species ancient group that once were the dominant forests on land; today, common in temperate forests; many are epiphytic; distinctive alternation of generations; some with two different kinds of spores

Conifers & Allies (760 species) have much more efficient vascular tissue than ferns can grow larger, taller; most are trees or shrubs with needle-like leaves; sexual reproduction only by male and female cones; male cone produces pollen that is blown by wind to female cone; fertilized egg becomes a naked seed borne on the female cone Conifers (Phylum Coniferophyta) 590 species conifers group contains one of world’s most massive organisms & world’s tallest organism: Coastal Redwood; nearly all are perennial trees & shrubs; in most conifers, leaves are needle or scale; nearly all conifers are evergreen; many conifers produce resin; no asexual reproductive organs; greatly reduced alternation of generationsSexual reproduction becomes the main means of reproduction; sexual reproductive organs are cones; male cones produce pollen; zygote develops into seed; the seeds are exposed usually on a cone Cycads (Phylum Cycadophyta) 100 species cone bearing palmlike plants of tropics and subtropics; living fossils from age of dinosaurs; similar to conifers but seed structure is more primitive Ginkgoes (Phylum Ginkgophyta) 1 species consists of a single species that was once thought to be extinct; today is widely cultivated; with distinctive fan shaped leaves; as seed matures on female tree the outer fleshy covering gives off a foul odor Gnetophytes (Phylum Gnetophyta) 70 species group of unusual, highly adapted plants in three genera; most efficient vascular tissue of the conifer group; in some the cone clusters resemble flowers of flowering plants

Flowering Plants (235,000 species, 90% all plants) dominant plants in world today90% of all living plant species; highly adaptable vegetative organs; complex symbioses with fungi, bacteria and animals enhance survival and efficiency; much more efficient transport tissues; no asexual reproductive organs or spores produced; sexual reproductive organ is the flower; seeds protected within a fruit Monocots (Class Monocotyledons) 65,000 species floral parts in 3’s; leaves are long tapered blades with veins; stems with scattered vascular bundles; seeds with 1 cotyledon Dicots (Class Dicotyledons) 165,000 species floral parts in 4’s and 5’s; leaves broad with netted veins; stems with vascular bundles in one large circle; seeds with 2 cotyledons