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(Last Modified On 11/16/2012)
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(Last Modified On 11/16/2012)
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Genus
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DESMANTHUS Willd.
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PlaceOfPublication
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Sp. P1. 4:1044. 1806
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Synonym
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Acuan Medik. Theodora, 62. 1786. Darlingtonia DC. in Ann. Sci. Nat. Bot. 4:97. 1825. Acuania Ktze. Rev. Gen. P1. 1:158. 1891.
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Description
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Perennial, small, usually diffuse or decumbent shrubs, or subherbaceous. Leaves moderately small, bipinnate, the pinnae one to many pairs opposite on the rachis, the leaflets few or many pairs, opposite; petiole short, either it and/or the rachis bearing one or more subcupular glands, very rarely eglandular; leaflets small, ob- scurely veined in most species, glabrous or infrequently pubescent; stipules seti- form. Inflorescence of axillary, pedunculate heads, the peduncle usually slender; head dense, usually few-flowered, the flowers more or less erect and the head then less than hemispherical; floral bracts nearly lanceolate, apparently never peltate as in most species of Leicaena. Flowers small, sessile, whitish or greenish; calyx synsepalous, more or less campanulate, 5-dentate; corolla essentially polypetalous, 5-parted, valvaze, the petals narrowed basally; stamens 5 or 10 (staminodes 5 or 0), free, normally exceeding the perianth; anthers comparatively larger as in Leucaena, not smaller as in Acacia, eglandular; ovary subsessile, bilateral, several-ovulate, usually glabrous; style thickened above into a truncate-concave stigma. Legume small, linear, flat, 2-valved, straight or curved, sometimes somewhat constricted between the seeds, dehiscent from the apex (the rather thin, dehisced valves sub- persistent), subseptate or continuous; seeds usually oblique, compressed.
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Habit
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shrubs
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Distribution
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Temperate, subtropic and tropic regions of the New World; introduced into the Old World.
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Note
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DesmantIus is obviously close to Leucaena, the basic floral and fruit characters being almost identical. However, whereas Leuicaena consists chiefly of arborescent species, species of Desmantbus are small shrubs or subherbaceous. In Central America additional characters serve to rather readily separate these genera, the more obvious of which are used in the key to the genera. Desmanthus is a small genus, but exceedingly troublesome from the standpoint of specific delimitation. As collections have accumulated it has become apparent that many of the characters on which species had been formulated do not hold constant, and that intergradation is rampant 'between almost all "species." Two specimens may appear distinct, but usually "'connecting" specimens exhibiting all degrees of intergradation can be found to link them. Thus, for practical reasons, if no other, not more than a handful of species appear worthy of recog- nition, and even these may not be readily distinguishable. On the basis of general observation of the genus the three "species" reportedly occurring in Panama are here combined under the oldest name, which thus considered is the only species known from Central America.
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