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Seed Plants. Seed Plants. Seed - an embryo of a plant encased in a protective coating & surrounded by a food supply. General Characteristics. Life cycles alternate between gametophyte & sporophyte generations Do not require water for fertilization. Seed Plants.
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Seed Plants • Seed - an embryo of a plant encased in a protective coating & surrounded by a food supply
General Characteristics • Life cycles alternate between gametophyte & sporophyte generations • Do not require water for fertilization
Seed Plants • Seed plants are divided into 2 groups: • Gymnosperms • Cones – sporophyte structure where gametophytes grow & mature • Seeds exposed directly on the surfaces of cones • Angiosperms • Flower - sporophyte structure where gametophytes grow & mature • Seeds within a layer of tissue that protects the seed
Pollination • Pollen Grain • Contains the male gametophyte • Pollination – when pollen grain is carried to the female reproductive structure by wind, insects, or small animals
Gymnosperms – “Naked Seed” • Most gymnosperms & some angiosperms are wind pollinated
Groups of Gymnosperms • Gnetophytes • About 70 present-day species • Mostly desert-type habitats • Cycads • Palm-like plants that produce large cones • Mostly tropical & subtropical habitats
Groups of Gymnosperms • Ginkgoes • Only one species, native to China • Survives because of cultivation • Conifers • The largest & most common gymnosperms are the conifers – more than 500 known species • Includes pines, spruces, firs, cedars, sequoias, redwoods, junipers, & yews • Most are evergreens, retaining their leaves throughout the year
Angiosperm Facts • Angiosperms have a unique reproductive organ called FLOWERS • Many produce fruit = a wall of tissue surrounding a seed • The seed leaves of plant embryos are called cotyledons • Flowers that complete an entire life cycle within one growing season are called –annuals • Most are pollinated by animals
Monocots and Dicots – 2 classes of Angiosperms • Named for the number of seed leaves (cotyledons) in the plant embryo • Cotyledon helps provide a food source for the developing plant
Flower Seed Root Stem Leaves Monocots • Cotyledons = 1 • Root = Fibrous root • Stem = vascular bundles scattered throughout • Leaves = Parallel venation • Flower = parts in multiples of 3
Flower Seed Root Stem Leaves Dicots • Cotyledons = 2 • Root = taproot • Stem = vascular bundles arranged in a ring • Leaves = Branched venation • Flower = parts in multiples of 4 or 5