Mecranium ovatum Cogn.

  • Family

    Melastomataceae (Magnoliophyta)

  • Scientific Name

    Mecranium ovatum Cogn.

  • Primary Citation

    Symb. Antill. (Urban) 7: 528. 1913

  • Type Specimens

    Specimen 1: Isosyntype -- M. D. Fuertes Lorén 1500

  • Description

    Description Author and Date: James D. Skean, Jr., January 2011, based on Skean, J. D., Jr. 1993. Monograph of Mecranium (Melastomataceae-Miconieae). Syst. Bot. Monogr. 39: 1-116.

    Type: [DOMINICAN REPUBLIC] "SANTO DOMINGO." Barahona: Sierra de Baoruco, near Barahona, between the forks of the rivers Cañada Maluca, 1450 m, fl, Apr 1912, Fuertes 1500 (holotype: B, destroyed; isotypes: A-2! BR-2! F! G! GH! L! NY! S! US!).

    Description: Shrub or small tree to ca 6 m tall; older stems often nodose. Twigs slightly to moderately 4-angled, 1.5-3 mm in diameter, smooth, essentially glabrous, but youngest buds and nodal ridges often with a few unbranched to irregularly branched and matted multicellular hairs; internodes (0.8-) 1.3-5.2 (-6.9) cm long. Leaf blade (3.1-) 4.1-9.9 (-13.1) cm long, (1.7-) 2.3-5.1 (-5.5) cm wide, ovate or elliptic, rarely obovate, coriaceous, very slightly curved abaxially; apex acuminate, rarely acute or obtuse; base cuneate or slightly decurrent, less commonly acute or obtuse; margin plane or often slightly revolute near base, minutely serrate on distal ca 3/4; venation acrodromous, suprabasal, usually with 1 pair of conspicuous secondary veins joining midvein 0.5-5.5 mm above lamina base, and 1 pair of inconspicuous, intramarginal secondary veins; adaxial surface with midvein, largest secondary veins, and tertiary veins strongly impressed when fresh, but flattening upon drying; abaxial surface with midvein and largest pair of secondary veins raised, the intramarginal secondary veins and tertiary veins less raised, the quaternary and higher order veins usually slightly raised in dried material, the surface essentially glabrous, but with some scattered minute glandular hairs present; marsupiform domatia and persistent tufts of hairs absent on abaxial surface in axils at junction of midvein and largest pair of secondary veins. Petiole 5-21 (28) mm long, glabrous. Inflorescences borne in leaf axils and on leafless nodes below leaves, 1-3 branched, (1.3-) 1.5-4 (-6) cm long, (0.4-) 0.6-3 (-4) cm wide, the caducous bracts to ca 1.9 mm long; peduncle (2-) 4-13 (-15) mm long. Hypanthium 1.2-1.6 mm long, 1-1.5 mm wide, slightly obconical or subglobose, sparsely pubescent with minute glandular hairs, the portion free from ovary ca 0.6 mm long; portion of calyx bearing external teeth 0.2-0.4 mm long. Calyx teeth ca 0.2 mm long, 0.2 mm wide. Calyptra present in bud, dome-like, with a caducous apiculum to ca 0.1 mm long. Petals 1.2-1.6 mm long, 1.2-1.4 mm wide, obovate, slightly cupped adaxially, white, spreading; apex rounded, emarginate. Stamens white; filament narrowly ovate, 1.2-1.4 mm long, ca 0.4 mm wide; anther narrowly obovate, 1.2-1.4 mm long, ca 0.35 mm wide, the anther sacs 0.4-0.6 mm long, opening confluently by a single, gaping foramen, septum torn. Ovary inferior, 0.7-1.1 mm long, 1-1.2 mm wide, the apical appendage ca 0.4 mm high; style white, 2.5-3 mm long, ca 0.3 mm wide, straight or slightly curved; stigma 0.3-0.4 mm wide. Berries ca 4 mm in diameter, purple-black, glabrous or with a few minute glandular hairs; seeds ca 0.7 mm long, 0.4 mm wide. Fig. 37.

    Habitat and Distribution: Hispaniola: endemic to broad-leaved cloud forests of the Sierra de Baoruco of the Dominican Republic; 800-1750 m, most common at 1300-1450 m. (Fig. 38).

    Phenology: Flowering from late February to May with most fruits reaching maturity by June.

    Taxonomy and Systematics: Mecranium ovatum is a glabrous species with broadly ovate or elliptic leaves with strongly impressed veins. The impressed veins are obscured somewhat in pressed specimens, but can still be observed. Under 20x or higher magnification the leaf abaxial surface can be seen to have its smallest veinlets slightly raised, unlike the flattened veinlets of M. multiflorum, the species most similar to M. ovatum. The geographical distribution of M. ovatum, occurring just to the east of the range of M. multiflorum in the Massif de la Selle-Sierra de Baoruco, makes it tempting to speculate that this species originated as a peripheral isolate of M. multiflorum. Mecranium ovatum is similar in leaf shape and vein impression to M. puberulum of the Massif du Nord-Cordillera Central. However the latter has densely pubescent twigs and leaves with five major longitudinal veins. The classical locality of collection for this species is known by botanists as "Monteada Nueva." These cloud forests east of the town of Polo are rich in plant species endemic to the Sierra de Baoruco.

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