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(Last Modified On 3/6/2013)
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(Last Modified On 3/6/2013)
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Genus
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MACHAERIUM Pers.
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PlaceOfPublication
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Syn. P1. 2: 276. 1807.
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Description
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Shrubs, trees or high-climbing woody lianas, the wood yielding orange or red sap. Leaves imparipinnate, the leaflets few to numerous, alternate; stipelles ab- sent; stipules often spinescent. Racemes axillary or terminal, these often numerous, cymoid; bracts usually small; bracteoles usually persistent. Flowers small, often dense, the hypanthium truncate, the teeth very short, usually truncate or obtuse; vexillum broad, usually emarginate; wing and carinal petals coherent distally along the lower margin; stamens 10, monadelphous or diadelphous and often with 2 fascicles of 5 stamens, the anthers small, usually basifixed, dehiscing longitudinally; stipe of the ovary surrounded by a glandular collar, the style slender, the stigma scarcely differentiated. Fruits stipitate, flat, samaroid, the seminiferous area proxi- mal, incrassate, the wing attenuate, reticulate, the seeds variable in shape.
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Note
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A genus of approximately 300 species widely distributed in the tropics of the New World and the Old World. The Panamanian species of Machaerium fall nat- urally into two groups, one with multifoliolate leaves, and the other with few leaflets. Pittier's work on Machaerium of Mexico and Central America (Contr. U.S. Nat. Herb. 20: 467-477. 1922) includes six species which occur in Panama, three of which are retained here. In Panama Machaerium is the largest genus of the Dalbergieae, challenged only by Lonchocarpus H.B.K.
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Key
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a. Fruit with the wing straight or slightly curved. b. Leaves with 20-80 leaflets. c. Leaflets palmately veined - -1. M. CHAMBERSII cc. Leaflets pinnately veined. d. Wing of the fruit relatively thick and not drying red. e. Costa of the leaflets almost invisible above; seminiferous area of the fruit distinctly marginate on the upper margin -2. M. GLABRIPES ee. Costa of the leaflets obvious above; fruits not obviously margin- ate. f. Leaflets 20-25. g. Leaflets glabrous, 0.3-0.6 cm. wide; staminal sheath usually hairy distally -3. M. CIRRHIFERUM gg. Leaflets pubescent, 1-2.5 cm. wide; staminal sheath glabrous -4. M. BIOVULATUM ff. Leaflets 25-80, usually pubescent beneath. g. Unarmed trees; rachis of the leaves up to 8 cm. long; hypanthium densely aurous-puberulent; staminal sheath pubescent -5. M. ARBORESCENS gg. Armed woody vines or trees; rachis of the leaves 4-15 (-30) cm. long; hypanthium glabrous (except few hairs on the teeth); staminal sheath glabrous. h. Wing and carinal petals falcate; free filaments of the stamens as long as or longer than the sheath; style 1.5-3 mm. long - 6. M. ISADELPHUM hh. Wing and carinal petals not falcate; free filaments of the stamens less than half the length of the sheath; style 0.5-1.5 mm. long 7. M. PURPURASCENS dd. Wings of the fruit paper-thin and drying red. e. Leaflets obtuse or rarely rounded at the apex, scarcely pubescent; hypanthium puberulent - 8. M. CAPOTE ee. Leaflets rounded at the apex, densely pubescent; hypanthium glabrescent, except for scattered bulbous trich-omes 9. M. LONGIFOLIUM bb. Leaves with 5- to 16 leaflets. c. Leaflets 5-7, long-acuminate. d. Leaflets elliptic; flowers blue; bracteoles wider than long, not carinate; hypanthium glabrescent (except the teeth); upper margin in the wing petals straight; fruit with the wing up to 3 cm. wide, not conspicuously thickened on the lower margin - 10. M. ARBOREUM dd. Leaflets ovate or oblong, rarely elliptic; flowers white; bracteoles at most as wide as long, carinate; hypanthium minutely puberulent; upper margin of the wing petals oblique; fruit with the wing up to 1.8 cm. wide, the lower margin 1-2 mm. thick -11. M. DARIENSE cc. Leaflets 6-16, not long-acuminate (except in M. pachyphyllum). d. Leaflets coriaceous, long-acuminate; rachis of the le af about 2 mm. wide; flowers about 15 mm. long -12. M. PACHYPHYLLUM dd. Leaflets chartaceous or membranous (subcoriaceous in M. seeman- nfi), obtuse to short-acuminate; rachis of the leaf 0.05-1 mm. wide; flowers about 10 mm. long. e. Leaflets 6-13, oblong, lanceolate or elliptic, obviously acuminate, 0.7-2 (-7) cm. wide; vexillum subcordate at the base, the claw obscure; wing petals narrowly oblong, the blade almost as wide proximally as distally; at least one filament of the stamens pubescent -13. M. SEEMANNII ee. Leaflets 9-11, oblong, obtuse or vaguely acuminate, 2-4 cm. wide; vexillum subcuneate at the base, the claw obvious; wing petals subrotund, the blade much wider distally than proximally; filaments of the stamens glabrous .. 14. M. WOODWORTHII aa. Fruit with the wing very broadly lunate 15. M. LUNATUM
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