Monographs Details: Brunellia acutangula Humb. & Bonpl.
Authority: Cuatrecasas, José. 1985. Brunelliaceae (supplement). Fl. Neotrop. Monogr. 2: 28-103. (Published by NYBG Press)
Discussion:The holotype of the species (Cuatrecasas, 1970, p. 167) is J. C. Mutis in "Humboldt & Bonpland Herbarium," photographed by Macbride with the number FM 34642. Another specimen from the Bonpland (or general P) herbarium, with a handwritten generic description by Bonpland is an isotype, and it is the specimen depicted in Killip’s photograph no. 419. The Mutis 4147 9 specimens in MA and US are isotypes.

It is characteristic of B. acutangula for the young terminal branches to have a lanuginous indument of short, flexuous and crisped, patent trichomes, turning glabrate. The follicles, as well as the calyces, also have a short subcrisped-lanate tomentum without bristles; the ripe endocarp dry and open, is rather turtle-shaped and 7-9 mm broad. The typical outline of the leaf blade is oblong-lanceolate and acute at both ends; it may vary to oblong with less attenuate ends or to broadly elliptical and subacute or subobtuse at one or both ends. The tendency of the species to have broader leaves is especially noticeable at the center of its range-in Venezuelan populations (the region of Pueblos del Sur)-but there is no consistency to be seen in the populations in such variations.

With respect to the flower diagram, the typical species, in Cundinamarca, is overwhelmingly 4-merous, whereas the proportion of 5-merous flowers becomes equal or dominant in some populations in Venezuela (Páramo del Batallón, Páramo de las Coloradas, etc.). It is noticeable too that, on the slopes of the Sierra Nevada de Merida at the northern end of its range, there can be found the very typical form of the species, with oblong-lanceolate blades and predominantly 4-merous flowers.

Brunellia acutangula, the only species of section Simplicifolia in Venezuela, probably migrated from the Eastern Cordillera of Colombia, covering the area NE to the Sierra Nevada de Mérida during the recession of the last glaciation. It is significant that typical representatives of the species can be found in the Merida region. Differentiation started taking place in the center of the whole range, in the rather isolated mountain ranges of Pueblos del Sur. Aberrant specimens found in this area with leaves somewhat resembling B. tomentosa, are only partial deviations of B. acutangula without any correlation in other features.
Distribution:Colombia South America| Cundinamarca Colombia South America| Santander Colombia South America| Mérida Venezuela South America| Táchira Venezuela South America|