Presentation on theme: "Units 22 and 23 SEED PLANTS. Life Llife Cylce of Nonseed Plant Life Cycle Flagellated sperm must swim Seed Plant Life Cycle Pollination."— Presentation transcript:
Units 22 and 23 SEED PLANTS
Life Llife Cylce of Nonseed Plant Life Cycle Flagellated sperm must swim Seed Plant Life Cycle Pollination
Highlights in the History of Seed Plants Late in the Devonian, some plants developed secondary growth: thickened woody stems of xylem
How Did Seed Plants Become Today’s Dominant Vegetation? Surviving seed plants fell into two groups: Gymnosperms: pines and cycads Angiosperms: flowering plants
Gymnosperms Any vascular plant that reproduces by means of an exposed seed, or ovulevascular plant “Naked Seed”
Gymnosperms Four major phyla of living gymnosperms: ( a)Cycads: Cycadophyta Sago palm Cone-bearing palm like tropical dinosaur food ?
Gymnosperms b)Ginkgos: Ginkgophyta One living species, Ginkgo biloba Seed coat stinks Polluted areas 1945 atom bomb The ginkgo is a living fossil, recognizably similar to fossils dating back 270 million years.
Gymnosperms (c) Gnetophytes: Gnetophyta Shrubs, trees, or vines the group is a small one, consisting of three families, each with one genus, totaling 68 species Ephedra *ephedrine
Gymnosperms (D)Conifers Coniferophyta largest group of gymnosperms pines, hemlock, spruce, evergreen conifers leaves stay all season sap ----antifreeze first real development of wood dead transport tissue
Angiosperms Flowering plants are the dominant plant today
Angiosperms They are the largest group of plants with about 90% of all plant species..
A Angiosperm Protected Seeds
Angiosperms FLOWERS are the exclusive reproductive organ of angiosperms “The earth laughs in flowers ” Ralph Waldo Emerson
What Features Distinguish the Angiosperms? Angiosperm: “enclosed seed”
Angiosperms Male reproductive structures Stamen Anther Filament bear microsporangia - sperm ( pollen) Female reproductive structures Carpel Stigma, style, and ovary bear megasporangia -egg (one or more carpel make up a pistil)
Angiosperm Pollen B - Dandelion (Taraxacum sp.) Transmission electron microscopy F - Pine (Pinus sylvestis): Light microscopy G - Mixed pollen grains (bright field light microscopy, stained)
Anigosperms Flowers may have contributed to the enormous success of angiosperms. The flowers attract a pollinators which carry pollen to other individuals of the same species
Angiosperms Attracted to sweet smells Need landing platform Attracted to sweet smells Need landing platform Attracted to strong smells Can hover; nocturnal Attracted to strong smells Can hover; nocturnal Can hover Prefer red color Can hover Prefer red color Need bigger landing platform Like bright colors Need bigger landing platform Like bright colors
Angiosperms Double fertilization Sperm A leads to the formation of a Seed Sperm B leads to the formation of an endosperm (a nutritive tissue within the seed that feeds the developing plant embryo)
Flowering plants are divided into two groups
Cotyledon? Embryonic seed is the first leaf or set of leaves that sprout from a seed Store nutrients for the embryo
A cotyledon – “seed leaf” contain nutrients for growth during embryonic development upon germination, the cotyledon may become the embryonic first leaves of a seedling.