Monographs Details: Macrolobium campestre var. arboreum R.S.Cowan
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:Latin Diagnosis - Arbor ad 35 m. alta, ramulis, petiolis, rachibus, petiolulisque glabris vel raro pilosulis sed glabrescentibus. Petiolus 5-23 mm. longus, teres. Folia 2-3-jugata, pari- vel pseudo-imparipinnata; rachibus (10-)20-45 mm. longa, leviter sulcatis. Petiolulus 2-4 mm. longus. Foliola 40-80 mm. longa, 20-35 mm. lata, ovata, lanceolata vel elliptica, ad basim plerumque obtusa, interdum acuta, ad apicem acuminata, raro acuta. Inflorescentiae 5.5-12 cm. longae,axe pilosulo; bracteis 9 mm. longis, 3 mm. latis, lanceolatis, acuminatis, ambobus lateribus puberulis; bracteolis 6-7 mm. longis, 3.5 mm. latis, ellipticis, pilosulis. Hypanthium glabrum. Petali lamina 3.5-5 mm. longa, 6 mm. lata, transverse ovalis, unguicilo 4.5 mm. longo. Ovarium glabrum, 2-ovulatum, gynophoro 3.5 mm. longo, puberulo. Fructus immaturus 12-13 cm. longus, 4 cm. latus, oblongus, apicem versus latior, glaber, carpophoro 6-13 mm. longo, puberulo.

Distribution and Ecology - Additional Specimens: BRAZIL: campina d'Arumateua, Rio Tocantins, Para, July 1916, Ducke 16261 (US); in insulis Breves aestuarii amazonica prope flumen Macujurbimzinho, Nov. 1922, Ducke 16943 (U); near mouth of Rio Embira, Amazonas, June 1933, Krukoff 4953 (A, F, G, MO, NY, U, UC, US).

Discussion:

Type Collection: A. Ducke 16532, "campinas sublonnens, Gurupa," Para, Brazil, Sept. 1916 (HOLOTYPE US, isotypes G, P).