Different kinds of seeds o taxus yew with fleshy

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Different kinds of seeds o Taxus (yew) with fleshy appendages (not fruits) o Many conifer seeds are winged and wind dispersed o Pinus greggii: serotinous cones take a fire for seed to be released. Heat from fire melts the glue and they open up Lodgepole pine forest following fire: from serotinous cones all the plants are the same age o Pine nuts are harvested from several different pine species
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o Juniper “berries” (flavoring of gin) Fertilization The unification of the sperm and the egg o Gymnosperms Distinguishing characteristics Seeds Gametophyte dependent on sporophyte More advanced vascular tissue Water not needed for reproduction (pollen carried by wind) Microspores and megaspores (heterosporous) o Angiosperms All angiosperms are classified in a single division, Anthophyta the name comes from the greek anthos, flower Seed is enclosed in fruit Flowers The flower is an angiosperm structure specialized for sexual reproduction Many species are pollinated by insects or animals, while some species are wind-pollinated o Animals will carry the pollen for some A flower is a specialized shoot with up to four types of modified leaves: o Sepals, which enclose the flower o Petals, which are brightly colored and attract pollinators o Stamens, which produce pollen on their terminal anthers o Ovary, which encloses ovules Have to be showy to attract the animals (design and scent) Flowers are not there to help with reproduction (just to be pretty) Gymnosperms don’t have ovaries
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Ovules have the immature seeds Carpal is part of the pistil Angiosperms 12/7/12 o History Appeared 150 mya Diversified greatly last 65 mya along with insects Now dominant plant life form More than 250,000 species o Have seeds and flowers o Life cycle Much reduced gametophyte Male gametophyte = pollen Female gametophyte = embryo sac o Significance of the style and the stigma o Many rely on animals for pollination o Most advanced vascular tissue o Male gametophyte in angiosperms 2-celled pollen Generative cell divides to form 2 sperm nuclei Tube cell produces the pollen tube o Pistil in angiosperms Interactions between stigma/style and pollen are important Stigma, style, and ovary = pistil Pollen tube has two sperm nuclei o Double fertilization in angiosperms One sperm fertilizes the endosperm mother cell (central cell); the other fertilizes the egg cell
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o Angiosperm life cycle o o Self-incompatibility systems Gametophytic (multiple alleles) Homeomorphic sporophytic Heteromorphic sporophytic (ex. Distyly) o Other controls on offspring quality Selective fruit abortion Selective ovule abortion o Pollination Bee pollination Plants provide pollinators rewards of pollen and/or nectar Brenda’s Yellow Cryptantha Wind pollinated species produce copious pollen and ack odors and showy colors Self-pollinating species do not invest in showy flowers
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