Monographs Details: Macrolobium discolor var. egranulosum R.S.Cowan
Authority: Maguire, Bassett, et al. 1953. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 8 (2): 87-160.
Family:Caesalpiniaceae
Description:Latin Diagnosis - Arbuscula 2-3 m. alta, ramulis pilosulis. Stipulae 5 mm. longae, subulatae vel subulato-lanceolatae, intus glabrae, extus pilosulae. Petiolus 2-5 mm. longus, pilosulus. Foliorum lamina 3-5-jugata, paribus 8-21 mm. separatis; rachibus 2.5-4.5 cm. longis, angustissime alatis, pilosulis. Foliola 1.5-4 cm. longa, 0.5-2.5 cm. lata, oblonga vel oblongo-ovalia, in costa supra puberula, infra sparsissime pilosula vel glabra, margine plana; costa plana vel leviter saliens supra, infra valde saliens, venulae prominentes. Inflorescentiae 3-10 cm. longae, axe puberulo; bracteolae 5.5-6.5 mm. longae, 3-5-4 mm. latae, ovales, glabrae intus, extus puberulae. Hypanthium 1-1.5 mm. longum,puberulum. Sepala adaxilia 2 mm. longa, 1 mm. lata vel nulla, sepala cetera 2-3.5 mm. longa, 1-1.5 mm. lata, glabra vel ad apicem ciliolata. Petali lamina 4.5 mm. longa, 5-6 mm. lata, plus minusve transverse ovalis. Filamenta 18-20.5 mm. longa, sparse villosula ad basim. Stigma subcapitellatum. Stylus 15.5-20 mm. longus, ad basim sparsissime pilosulus. Ovarium 1.5-2 mm. longum, 1 mm. latum, oblongum, marginibus villosis, 2-4-ovulatum, gynophoro 1.5-2 mm. iongo, villosulo. Fructus 5 cm. longus, 2.5 cm. latus, oblongus, marginibus sparse pilosulis; semina 1.5 cm. diametro, suborbicularia, testa tenuissime membranacea.

Distribution and Ecology - Additional Specimens: VENEZUELA: Sabanita, northwest base of Cerro Moriche, Jan. 1951, Maguire, Cowan & Wurdack 30977 (BM, COL, NY).

Discussion:

Type Collection: B. Maguire, R. Cowan & / . Wurdack 30842, "frequent shrub to 2 m. tall, petal white, filaments red, calyx red, dry open eastern slopes of Cerro Moriche, Rio Ventuari, Amazonas, Venezuela," Jan. 1951 (HOLOTYPE NY, isotypes F, G, GH, IAN, K, MO, P, RB, U, UC, US, VEN).

The affinity of this species for M. multijugum is unmistakable but M. discolor differs by its short peduncles, somewhat differently-shaped epunctate leaflets and the very different shape of the fruit.

The typical variety and var. caudiculatum are characterized by the presence of great quantities of granular wax-bodies which are of uniform size and form and are distributed evenly over the lower surface of the leaflets. Although this condition is not peculiar to these taxa, it does serve to distinguish them from the other variety.

Var. caudiculatum may be distinguished from the typical variety by its pubescent under surfaces of the leaflets and the more uniform size of the sepals. It is, then, not strikingly distinct and certainly not worthy of the specific rank accorded it by Ducke.

Var. egranulosum differs, in addition to the difference noted above, by its smaller bracts and bracteoles, by the villose ovary margins, and by its plane leaflet margin. While the other two varieties are obviously quite closely related, this one is not clearly related to either of the others.