seed plants (chapter 30)
seed plant evolutionary hallmarks 1) microscopic gametophytes protection (UV, desiccation) nutrition from parents (increased chance for survival)
microscopic gametophytes... seedless, nonvascular - mosses, liverwort, hornworts seedless, vascular - ferns, spike mosses, whisk ferns, horsetails
microscopic gametophytes... seed - gymnosperms, angiosperms
seed plant evolutionary hallmarks 2) seeds more complex than spores (packaged embryo and protective coat)
seeds... protection of the gametophyte!!!
seed plant evolutionary hallmarks 3) pollen eliminated need for liquid for fertilization non-flagellated sperm pollen grains covered in sporopollenin great for dispersal
seed plant systematics Gymnosperms (gymno naked; sperm seed) >760 spp. from progymnosperms (seedless) during Devonian radiation during Carboniferous and early Permian dominant during Mesozoic conifers cone-bearing plants (e.g. pines) cone is usual reproductive structure ovules and seeds develop on sporophylls better adapted to poor, rocky soils and cold
Gymnosperms... Cycadophyta ~100 spp. important during Triassic (248 mya) dioecious (dio two; ecious house) pollen and ovulate cones on separate plants tropical and subtropical superficially resemble palms palms are angiosperms e.g. sago palms
e.g. Cycadophyta...
Gymnosperms... Ginkgophyta single, extant species Ginkgo biloba popular ornamental native to eastern China oldest species of living tree deciduous no cones completely exposed seed
e.g. Ginkgophyta...
Gymnosperms... Gnetophyta ~70 spp. believed most closely related to Angiosperms three distinct genera
e.g. Gnetophyta... Ephedra (Mormon tea) shrub in N. American deserts Gnetum tropical; tree or vines Weltwitschia S. African deserts
Gymnosperms... Coniferophyta largest phylum (~550 spp.) name ( conifer ) from reproductive structure cone - cluster of scale-like sporophylls usually monoecious dominant N. Hemisphere e.g. pines, firs, spruces, larches, yews, junipers, cedars, cypresses, redwoods most evergreen limited photosynthesis possible in winter, ready to start at soon as spring! needle-shaped leaves in some is adaptation for dry climates contain thick cuticle among largest and oldest organisms on earth redwoods in California can reach over 100m bristlecone pine in California >4,600 years old!
e.g. Coniferophyta...
gymnosperm life cycle...
seed plant systematics Angiosperms (angio container; sperm seed) the flowering plants Anthophyta (one phylum) most diverse and widespread of all plants ~250,000 spp. (vs. only 720 spp. of gymnosperms) arose during Cretaceous dominant by end of Cretaceous continued dominance during Eocene (35-57 mya) flowers fruits
monocots & dicots...
flowers... specialized reproductive adaptation what makes plants sexy contributed much to success insects, other animals, or wind to transfer pollen
flower power...
Ophrys
fruits...(thickened ovary wall is the pericarp)
fruits... protects dormant seeds aid in dispersal many modifications kite or propeller device e.g. dandelions, maples animals for dispersal insects burrs to cling to animal fur edible fruits eaten seeds deposited during defecation
fruit structure variation...
types of fruits... simple aggregate multiple
angiosperm life cycle...
flowers; fruits seeds; pollen; microscopic gametophytes; spores retained vascularization; sporophyte dominant from protists to flowers... spores; multicellular; gametophyte dominant
plant comparison... feature moss fern conifer flowering dominant generation gametophyte sporophyte sporophyte sporophyte vascularization nonvascular vascular vascular vascular sperm flagellated flagellated non-flagellated (most) non-flagellated seed seedless seedless seed seed fruit no no no yes water required for fertilization yes yes no no pollen no no yes yes heterosporous no no (most) yes yes