Monographs Details: Diolena longidens Gleason
Authority: Maguire, Bassett, et al. 1953. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 8 (2): 87-160.
Family:Melastomataceae
Description:Latin Diagnosis - Suffrutex ramosus; folia valde dimorpha, majora ovato-oblonga supra medium pectinato-dentata, minora elliptica integra; flores 5-meri solitarii, breviter pedunculati; sepala fere semicircularia erosa, dentibus exterioribus subulatis multo breviora; D. repenti Gl. habitu valde affinis, differt dentibus exterioribus elongatis et ovario fimbriato.

Species Description - Stems suffruticose, much branched, 1-3 dm. tall, glabrous, when young strongly flattened and narrowly 2-winged, becoming thickened and sharply 4-angled; internodes 5-10 mm. long. Leaves very dimorphic: the larger ovateoblong, 12-17 mm. long, 7-9 mm. wide, obtuse, broadly acute at base, entire in the basal half, above the middle pectinate-dentate with strongly ascending teeth, glabrous except a few scattered brown scales on the lower side, 3-nerved, on petioles 1.5-2 mm. long; the smaller leaves essentially sessile, elliptic, 4-5 mm. long, abruptly acuminate, entire, 1-nerved. Peduncles solitary in the upper axils, 6-7 mm. long, subtended at base by a pair of reduced leaves, densely scabrously pubescent with stout curved-ascending hairs. Flowers solitary, 5-merous. Hypanthium cup-shaped, thin-walled, 2.8 mm. long, scabrous like the peduncle. Calyx-tube about 1 mm. long; sepals very thin, almost transparent, 2.6 mm. long from the torus, the free portion depressed-obovate, broadly rounded, conspicuously erose-ciliate; exterior teeth with a triangular base adnate to the base of the calyx, prolonged into a straight, spreading, subulate tip 5 mm. long. Petals and stamens lacking. Ovary superior, 3-celled, tipped with an erect, strongly fimbriate collar.

Discussion:

TYPE: from wet rocks on the escarpment of Cerro Sipapo, Bassett Maguire & Louis Politi 27505; New York Botanical Garden. Although stamens are lacking, its close similarity to D. repens, even in many details of structure, proves that the two are congeneric, but not that they belong to Diolena. Our species differs from Do repens in the greatly elongate and consequently very conspicuous exterior teeth of the calyx and in the fimbriate summit of the ovary.