Apocynaceae

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  1a. Flowers with a corona [Figs. 362,363,366]; carpels connate only by the thickened style-head; pollen coherent in masses; seeds always comose
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    Periploca

    2a. Plants lianas; corolla lobes densely villous adaxially; corona composed of 5 short, bifid, antepetalous lobes alternating with 5 narrow, thread-like lobes 4–8 mm long
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    2b. Plants herbs or vines; corolla lobes glabrous or minutely pubescent adaxially; corona either a whorl of 5 tubular- or scoop-shaped hoods or a fleshy, lobed cup
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      Cynanchum

      3a. Stems climbing or twining (at least the apical part of the plant); calyx and corolla lobes ascending to spreading [Fig. 366]; corona a fleshy, lobed cup [Fig. 366]
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      Asclepias

      3b. Stems upright, neither climbing nor twining; calyx and corolla lobes reflexed 
 [Figs. 362,363]; corona a whorl of hoods bearing internally near the base a slender, horn-like appendage (the horns absent in A. viridiflora) [Figs. 362,363]
• See list of 3 genera in 1b
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  1b. Flowers with only sepals and petals, lacking a corona [Figs. 359,360]; carpels apically connate with a common style and stigma; pollen grains not cohering in masses; seeds with or without a coma
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    Vinca

    4a. Flowers solitary from leaf-bearing nodes; corolla 20–50 mm wide in life; trailing plants with upright branches
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    4b. Flowers in terminal or both terminal and axillary cymes [Fig. 359]; corolla up to 10 mm wide in life; upright plants without trailing stems
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      Amsonia

      5a. Leaves alternate or irregularly scattered; petals blue; seeds lacking a coma of hairs
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      Apocynum

      5b. Leaves opposite; petals white, tinged or striped with pink, green-white, or yellow; seeds comose

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 Show photos of:   Each photo represents one genus in this family.