Almost all habitats very important economically

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Unformatted text preview: Angiosperms leaves; mostly tropical   Ephedra: bush with scale-­‐like leaves; arid regions   Welwitschia: produces only two leaves that split with age; SW Africa   All are dioecious   Double fer�liza�on in Gnetum and Ephedra (no endosperm)   Previously thought to be sister group to angiosperms (vessels, flower clusters, double fer�liza�on) Angiosperm diversity Seed plants: Angiosperms   Monophyle�c but very diverse group   Most successful and dominant plant group (found in almost all habitats)   Very important economically –  agriculture, clothing, wood, medicine, hor�culture   Uni�ng features (“ground plan”): –  Flowers –  Carpel enclosing ovules –  Seeds within a fruit –  Reduced male and female gametophyte –  Endosperm (double fer�liza�on) Parasitic/saprophytic ~600 spp. Smallest (2-3mm, duckweed) 70 spp. Tallest (>100m, Eucalyptus) Largest flower (Rafflesia) 1 sp. ~250 spp. Carnivorous >250,000 10 The angiosperm flower   Contributed to the enormous success of angiosperms? –  Evolu�onary flexibility of flower formats   Show remarkable varia�on   Defining characteris�cs   Ensure fer�liza�on of the ovule and development of fruit containing seeds   Determinate shoot that bears sporophylls   May arise terminally on a shoot or from the axil of a leaf   May be clustered in various ways into inflorescences   “Perfect” flowers (bisexual; hermaphrodite)   “Imperfect” flowers (unisexual; monoecy and dioecy) The angiosperm flower Perianth (sterile)   Sepals (calyx): protect developing bud, o�en green and thicker   Petals (corolla): o�en large and colorful, thinner, a�ract insects (pollinators)   Tepals: sepals and petals are similar The angiosperm flower “Perfect” flower (female and male parts in the same flower):   Develops from a bud   Flower parts evolved as modified leaves a�ached to a stem �p called a receptacle   General parts (whorls): –  Sepals (calyx) –  Petals (corolla) –  Stamens (anther and filaments), make up the androecium –  Carpels (pis�l), make up the gynoecium The angiosperm flower -­‐ reproduc�ve structures Androecium ♂   Stamens (microsporophyll): –  Filament –  Anther, two-­‐lobed, contains 4 pollen sacs (microsporangia) Filament 11 Placenta�on The angiosperm flower -­‐...
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