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Amsonia

Higher Taxonomy
Family: ApocynaceaeView DescriptionDichotomous Key

Common Name: DOGBANE FAMILY
Habit: Annual, perennial herb, shrub, tree, often vine; sap generally milky. Leaf: simple, alternate, opposite, subwhorled to whorled, entire; stipules 0 or small, finger-like. Inflorescence: axillary or terminal, cyme, generally umbel- or raceme-like, or flowers 1--2. Flower: bisexual, radial; perianth parts, especially petals, overlapped, twisted to right or left, at least in bud; sepals generally 5, fused at base, often reflexed, persistent; petals generally 5, fused in basal +- 1/2; stamens generally 5, attached to corolla tube or throat, alternate lobes, free or fused to form filament column and anther head, filament column then generally with 5 free or fused, +- elaborate appendages abaxially, pollen +- free or removed in pairs of pollinia; nectaries 0 or near ovaries, then 2 or 5[10], or in stigmatic chambers; ovaries 2, superior or +- so, free [fused]; style tips, stigmas generally fused into massive pistil head. Fruit: 1--2 follicles, (capsule), [berry, drupe]. Seed: many, often with tuft of hairs at 1 or both ends.
Genera In Family: 200--450 genera, 3000--5000 species: all continents, especially tropics, subtropical South America, southern Africa; many ornamental (including Asclepias, Hoya, Nerium, Plumeria, Stapelia); cardiac glycosides, produced by some members formerly treated in Asclepiadaceae, used as arrow poisons, in medicine to control heart function, and by various insects for defense. Note: Asclepiadaceae ("asclepiads"), although monophyletic, included in Apocynaceae because otherwise the latter is paraphyletic. Complexity of floral structure, variation in asclepiads arguably greatest among all angiosperms. Pattern of carpel fusion (carpels free in ovule-bearing region, fused above), present +- throughout Apocynaceae (in broad sense), nearly unknown in other angiosperms. Base chromosome number generally 11; abundance of latex, generally small size of chromosomes evidently have impeded cytological investigations.
eFlora Treatment Author: Thomas J. Rosatti, except as noted
Scientific Editor: Bruce G. Baldwin.

Amsonia
Habit: Perennial herb, erect, semi-woody. Leaf: alternate to subwhorled. Inflorescence: +- terminal, compound cyme. Flower: corolla salverform; filaments free, attached near top of corolla tube, unappendaged, anthers free from each other and stigma, pollen +- free; nectary 0 or a shallow ring around ovaries; style +- thread-like, stigma skirted at base. Seed: glabrous.
Species In Genus: 5--25 species: North America, Japan. Etymology: (John Amson, Virginia physician, 18th century)
eFlora Treatment Author: Thomas J. Rosatti & Lauramay T. Dempster
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Citation for this treatment: Thomas J. Rosatti & Lauramay T. Dempster 2016. Amsonia, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=10238, accessed on May 06, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on May 06, 2016.


Amsonia tomentosa
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© 2009 Keir Morse
Amsonia tomentosa
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© 2006 Steve Matson
Amsonia tomentosa
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© 2010 Neal Kramer
Amsonia tomentosa
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© 2009 Keir Morse
Amsonia tomentosa
click for enlargement
© 2008 Steve Matson
Amsonia tomentosa
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© 1998 Christopher L. Christie

More photos of Amsonia in CalPhotos