Brachyotum gracilescens Triana
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Authority
Wurdack, John J. 1953. A revision of the genus Brachyotum (Tibouchineae-Melastomataceae). Mem. New York Bot. Gard. 8 (4): 343-407.
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Family
Melastomataceae
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Scientific Name
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Description
Species Description - Trichomes smooth. Young branchlets quadrangular, sparsely strigulose and soon glabrescent, the nodal patent hairs to 2 mm. long. Petiole 5-10 mm. Blade 20-60 x 10-25 mm., ovate with the apex acute and base obtuse to rounded-truncate, thin and i.s. plane or somewhat rugose, the 3 primaries and 15-20 pairs of secondaries narrowly impressed above and narrowly elevated below; above very sparsely short-strigose or long-strigulose with broad glabrous strips along the primaries, the slender hairs mostly 1-2/mm.2 (occasionally as dense as 5-6/mm.2) with their basal 1/5-1/3 adherent; below sparsely to very sparsely loose-slenderlong-strigulose along the veins, the surface glabrous except for the sparse (3-15/mm.2) solitary glands. Flowers 4-merous, solitary, binate, or ternate on long (20-30 x 0.5 mm.) slender peduncles from opposite upper leaf axils, the bracteoles at the peduncular apex 1.5-3 x 0.3-0.6 mm. and early caducous. Pedicel 3-11 mm. below bracteoles, 1-5 mm. above; pedicellar bracteoles 1-1.5 x 0.2 mm., glabrous except for the appressed cilia and a few hairs abaxially on the single vein, very early caducous, absent in uniflorous inflorescences and usually absent in the center flower of the dichasium. Hypanthium 4-5 x 4-4.5 mm., 0.2-0.3 mm. thick medianly, sparsely strigulose, the slender hairs 3-5(-9)/mm.2 Sepals 3-4.5 x 3.5-5.5 mm., the apical 2-3.5 mm. broadly subulate and 1.5-2.5 mm. wide, the apices short-apiculate, united at bases 0.2-0.7 mm., the sinuses acute, outside glabrous except for a few hairs on the basal 1/3-1/2 of the midrib. Petals carmine to basally white with bright rose margins, 12-19 x 10-15 mm., asymmetrically obovate with the apices broadly rounded to obliquely truncate, the midvein sometimes with a small apiculus, the non-glandular cilia 0.1-0.4 mm. (the terminal one 0.6-1 mm.). Filaments 5~9 mm.; anthers 3.5-7.5 mm.; connective at anther base not at all extended nor free of the anther. Style 17-24 x 0.6-0.8 mm., exserted 2-6 mm. Ovary 4-5 x 2-2.5 mm., sparsely strigulose on the apical 0.3-1 mm. with conic setae, the apical lobes 0.2-0.4 mm. above the locules.
Distribution and Ecology - Distribution: central to southern Ecuador, alt. 2400-3000 m.
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Discussion
Type Collection and Locality: Spruce 6084 (HOLOTYPE K; isotypes BR, GBOIS, G-DEL, GH, P, S, W); "in silvis montis Tunguragua alt. 10,000 ped." (fide holotype), Prov. Tungurahua, Ecuador.
Type Photographs: Gleason 87-5 (holotype); F16710 (destroyed isotype at B).
B. gracilescens and its relatives, B.. fraternum and B. rugosum, form a group whose other relationships are obscure; they are somewhat suggestive of B. rostratum and its relatives in the slender peduncles, obtuse to truncate petals, and etuberculate anthers; however, the smooth hairs and/or large leaves are anomalous.