Monographs Details: Macrolobium colombianum (Britton & Killip) Killip var. colombianum
Authority: Cowan, Richard S. 1953. A taxonomic revision of the genus Macrolobium (Leguminosae-Caesalpinioideae). Mem. New York Bot. Gard. 8 (1): 257-342.
Family:Caesalpiniaceae
Description:Species Description - Branchlets glabrous or the very young ones sparsely pilosulose. Stipules 5 mm. long, 1.5 mm. wide, subulate-lanceolate, acuminate, persistent, sparsely puberulous on the outer surface. Leaves 5-6-jugate, the pairs 12-20 mm. apart. Petioles 10-15 mm. long, subalate-canaliculate; rachis 6.5-9 cm. long, the rachis and petioles puberulous on the upper surface, glabrous beneath. Leaflets 33-72 mm. long, 12-18 mm. wide, elliptic or oblong-elliptic, densely puberulous above on the costa, glabrous beneath, the venules prominulous. Inflorescences 7-9 cm. long, the axis glabrous, the peduncles 2-6 mm. long, sparsely and minutely puberulous; pedicels 5-6.5 mm. long, glabrous; bracteoles 8 mm. long, 4 mm. wide, oblanceolate, glabrous externally, sparsely appressed-puberulous within. Hypanthium 4.5-5 mm. long, on a stipe 2.5 mm. long, glabrous. Sepals 7 mm. long, 2.5-3 mm. wide, oblong, rotund-obtuse, glabrous. Corolla and androecium unknown. Stigma capitellate. Style about 15 mm. long, pilosulose basally. Ovary 2.5 mm. long, 1.5 mm. wide, oblong-oblanceolate, the margins densely pilosulose, the lateral surfaces glabrous, 3-4-ovulate; free portion of the gynophore 3 mm. long, pilosulose. Fruit unknown.

Discussion:

Figure 12.

Outea "(?)" colombiana Britton & Killip, Ann. N. Y. Acad. 35: 166. 1936.

Type Collection: / . Triana 4419, "Istmo de S". Pablo, Nouvelle-Grenade.-Prov. de Choco, hauteur 70 metr.," March 1853 (HOLOTYPE NY, isotypes BM, COL, US). Known only by the type collection.

The only near relative of this rather complex species is certainly M.trinitense, although there is a very remote connection with M. stenosiphon. M. colombianum is set off from its nearest relative by its leaves having a greater number of pairs of differently shaped leaflets, by its more or less pubescent ovary, and by the geographic distribution.

The varieties composing this species are based primarily on the distribution of the ovary pubescence, number of pairs of leaflets per leaf, shape of the leaflets, size and shape of the stipules, and the geographic distribution. Var. monagasense, with its numerous pairs of lanceolate-oblong leaflets and pubescent ovary, is not particularly closely related to either var. metaense or var. ocumatense, its nearest relatives. These latter varieties also have pubescent ovaries and/or fruit and differ from one another in the number of leaflet pairs, size of the stipules, and geographic distribution.

The glabrous ovary of the typical variety and var. bicuspidum serve to differentiate them from the other taxa of the same rank. Quite a number of characters separate them from each other. The more important of these are the size and nature of the stipules, number of leaflet pairs, petiole length and presence or absence of pubescence on the inflorescence.