Macrolobium microcalyx Ducke
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Authority
Cowan, Richard S. 1953. A taxonomic revision of the genus Macrolobium (Leguminosae-Caesalpinioideae). Mem. New York Bot. Gard. 8 (1): 257-342.
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Family
Caesalpiniaceae
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Scientific Name
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Description
Species Description - Shrub of 2 m. to tree 10 m. tall, the branchlets microscopically puberulous or occasionally glabrous. Petioles 2-6 mm. long, glabrous or puberulous on the upper surface, canaliculate. Leaf blades 3-5-jugate, the pairs 8-25 mm. apart; rachis 3-9 cm. long, glabrous or the axis minutely uncinate-puberulous on the upper surface. Leaflets 15-45 mm. long, 7-25 mm. wide, oval to oblong to oblong-obovate, the base inequilateral, the upper side cordate, the lower side acute to subobtuse, the apex rotund, retuse to emarginate, sometimes apiculate; upper surfaces minutely uncinate- or arcuate-puberulous on the costa, glabrous beneath; costa salient above, plane to subsalient beneath, the venules prominulous. Inflorescence 2-9 cm. long, the axis minutely puberulous, the peduncle 2-6 mm. long; bracts 1.5-2 mm. long, 1-1.5 mm. wide, caducous, triangular to triangular-ovate, acute, ciliolate, glabrous within, very minutely puberulous externally or rarely glabrous outside; pedicels 1-3.5 mm. long, very minutely puberulous; bracteoles 4.5-7 mm. long, 2-3 mm. wide, oblong to oblong-oval to oblong-obovate, villosulose within, appressed-puberulous externally. Hypanthium 1-1.5 mm. long, sparsely puberulous, sessile. Sepals five, free, the adaxial ones 0.5-1.5 mm. long, 0.5-1 mm. wide, triangular, acute to acuminate, glabrous, the other sepals I.5-3 mm. long, 1-1.5 mm. wide, triangular-lanceolate to lanceolate, acuminate to caudate-acuminate, glabrous. Petal blade 2.5-5.5(-7) mm. long, 4-5 mm. wide, transversely oval, the claw 2-4 mm. long, auriculate or merely expanded at the base, more or less pilosulose on the outer surface or rarely glabrous, villosulose within, sometimes sparsely so, claw ciliolate. Filaments (10-)l6-18 mm. long, villosulose in the-lower part.' Stigma capitellate. Style (8.5-)l 1-16.5 mm. long, villose basally. Ovary 1.5-2 mm. long, 1 mm. wide, oblong, 2-ovulate, villose on all surfaces, the gynophore 1.5-2.5 mm. long, villosulose, inserted on the base or up to midway on the adaxial hypanthial wall. Fruit unknown.
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Discussion
LECTOTYPE: A. Ducke (H.J.B.R. No.) 23298, "Estrada do Aleixo, Manaos," Amazonas, Brazil, Sept. 1929 (deposited RB, isolectotypes G, P, U, US).
The nearest relative of M. microcalyx is M. montanum, especially the typical variety of the latter. The following characters of M. microcalyx serve to distinguish it from its nearest relative: (1) its sepals are strongly dimorphic in both size and shape; (2) the ovary is villose on all surfaces; and (3) it usually has more pairs of leaflets per leaf.
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Distribution
Additional Specimens: BRAZIL: Amazonas: Camanaos, Sept. 1935, Ducke 34 (A, F, IAN, MO, NY, US); Camanaos, upper Rio Negro, Nov. 1929, Ducke (H.J.B.R. No.) 23299 PERU: Mishuyacu, near Iquitos, Dept. Loreto, 1929-30, Klug 140, 387, 1043 (NY, US).
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