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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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