Brachyotum naudinii Triana

  • Authority

    Wurdack, John J. 1953. A revision of the genus Brachyotum (Tibouchineae-Melastomataceae). Mem. New York Bot. Gard. 8 (4): 343-407.

  • Family

    Melastomataceae

  • Scientific Name

    Brachyotum naudinii Triana

  • Description

    Species Description - Trichomes smooth to very minutely and sparsely roughened. Branchlets quadrangular, moderately to sparsely short-strigulose. Petiole 2-5 mm. Blade 5-17 x 4-7(-10) mm., ovate to elliptic with the apex rounded to blunt-acute and the base obtuse to subtruncate, the 3 primaries narrowly impressed above and elevated below, the secondaries obscure or obsolete above and below; above sparsely strigulose, the hairs 1-4/mm.2 with their basal 1/3-2/3 adherent; below sparsely strigulose on the primaries, very sparsely on the surface 2-6(-10)/mm.2, the glands to 25/mm.2 and solitary or in small clusters at hair bases. Flowers usually solitary on short lateral branchlets, usually exclusively 4-merous, occasionally predominantly 5-merous. Pedicel 2-5 mm. above the last somewhat reduced persistent leaves (bracteoles ?). Hypanthium 4-7 x 3.5-6 mm., 0.3-0.5 mm. thick medianly, sparsely to moderately strigulose, the fine hairs (6-)8-16/mm.2 Sepals (4-)5-7(-9) x (3-)4-5 mm., oblong-ovate (rarely deltoid-ovate) with the apices rounded to broadly acute, united at bases 0.7-1.1 mm., the sinuses rounded-acute. Petals deep purple, 13-23 x 10-17 mm., asymmetrically or nearly symmetrically obovate with the apices broadly obtuse to rounded or truncate, the gland-tipped cilia 0.1-0.4(-0.6) mm. Filaments 3.5-7.5 mm., as long as the anthers; connective at anther base (0.6-)1-1.6 mm., free of the anther for Vi the length or slightly less, the blunt ventral lobes 0.2-0.4(-0.8) mm. Style 17-25 x 0.4-0.6 mm., exserted 4-7 mm. Ovary 4.5-7 x 3-4 mm., sparsely to moderately strigulose on the apical (0.6-)1.5-3 mm., the apical lobes 0.3-1 mm. above the locules.

    Distribution and Ecology - Distribution: central (to northern ?) to southeastern Peru, alt. 2700-4000 m.

  • Discussion

    Type Collection and Locality: Dombey s.n. (HOLOTYPE presumably at P; isotypes BM, BR, F, G-DEL, L, P); "Peruvia," Dept. Huanuco (or more probably Junin), Palca, fide Macbride (1941, p. 271).

    Type Photograph: F36134 (presumed holotype at P).

    Vernacular Names: Masuca (Cook & Gilbert 720); Ccehuincha (West 3662); Jehuincha (Stork & Horton 10763).

    One Paris isotype is labeled only "herb. Richard"; this specimen was used by Cogniaux in drawing up his erroneous description of B. microphyllum; the isotype in Cogniaux's herbarium (BR) is a branch from this Paris sheet; while no collector was indicated on the Paris specimen, it is undoubtedly part of the Dombey type collection.

    In the type collection, 17 of the 28 examinable flowers were 5-merous; in Sandeman 4610, 9 of 9; and in Stork & Horton 10218, 8 of 10. The remainder of the flowers in these collections and all of the 82 examinable flowers in all other cited specimens were 4-merous. The degree of pubescence roughening varied independently of the mery, the first two collections with predominantly 5-merous flowers being perceptibly roughened, and the third-mentioned smooth. The constantly 4-merous collections have pubescence scabridity between these extremes.

    B. naudinii may be distinguished from B. grisebachii by the shape of the sepals and petals, the glandular petal cilia, and the solitary flowers. From B. tyrianthinum, it differs in the smaller leaves and shorter, sparser, less roughened trichomes, as well as the adaxially glabrous sepals. However, there are a series of constantly 4-merous specimens from northern Peru having pubescence development very suggestive of B. tyrianthinum, but the trichomes are smooth; the pubescence on the upper leaf surface ranges from 3-9/mm.2 and the sepals are rather variable in shape, ovate to ovate-oblong with variably acute apices, but glabrous within. They include Stork & Horton 9962 (F, G-DEL, UC) from La Libertad, Ferreyra 3291 (USM) and Raimondi 3152 (USM) from Cajamarca, and Mathews 1259 (K) and Pennell 15530 (PH) from Amazonas. These specimens have been doubtfully referred to B. naudinii. Sandeman 4291 (K) from Piura is even more anomalous, possibly being a depauperate form of the preceding group; the calyx lobes are very narrowly oblong-lanceolate and leaves narrowly elliptic.