Mecranium puberulum Cogn.

  • Family

    Melastomataceae (Magnoliophyta)

  • Scientific Name

    Mecranium puberulum Cogn.

  • Primary Citation

    Symb. Antill. (Urban) 5: 450. 1908

  • 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: HAITI. [Dépt du Nord]: Massif du Nord, near Gonäives to Poste Marie Congo, in a shrubby, sunny place, 900 m, fl, Buch 782 (holotype B, destroyed; isotypes: BR-fragment! IJ!).

    Description: Shrub or small tree to ca 3.5 m tall. Twigs slightly to moderately 4-angled, 1.5-3 mm in diameter, smooth or slightly tuberculate-roughened, ferrugineous, youngest portions densely and evenly pubescent with brown unbranched to irregularly branched and matted multicellular hairs; internodes (0.8-) 1.1-4.5 (-5.5) cm long. Leaf blade (2.3-) 2.8-9.3 (-11.3) cm long, (1.2-) 1.5-4.8 (-5.4) cm wide, ovate or elliptic, coriaceous, often slightly curved abaxially; apex acuminate, rarely acute or obtuse; base rounded or obtuse, rarely cordate on juvenile plants; margin plane or often slightly revolute near base, serrate on distal ca 3/4, rarely throughout; venation suprabasal, usually with 2 pairs of conspicuous secondary veins, the largest joining midvein 0.5-3 (-6) mm above lamina base, and 1 pair of inconspicuous, intramarginal secondary veins; adaxial surface with midvein, 2 pairs of secondary veins, and tertiary veins strongly impressed in living material, usually flattening somewhat upon drying; abaxial surface with midvein and 2 largest pairs of secondary veins raised, the intramarginal secondary veins and tertiary veins less raised, the quaternary and higher order veins flat, the surface pubescent with hairs similar to those on stem concentrated on veins and in persistent axillary tufts at junction of midvein and largest pair of secondary veins, minute glandular hairs also present, marsupiform domatia absent at junction of midvein and largest pair of secondary veins. Petiole (2-) 6-26 (-33) mm long, densely pubescent with hairs similar to those on stem. Inflorescences borne in leaf axils and on leafless nodes below leaves, (1.1-) 1.7-3.2 (-3.6) cm long, (0.6-) 0.8-2.1 (-2.6) cm wide, 1-2 branched, the caducous bracts to ca 4 mm long; peduncle (3-) 5-13 (-16) mm long densely pubescent with hairs similar to those on stem. Hypanthium 1.5-1.8 mm long, 1.6-2.1 mm wide, slightly obconical or subglobose, moderately pubescent with minute glandular hairs, the portion free from ovary 0.5-0.6 mm long; portion of calyx bearing external teeth 0.2-0.5 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 0.2 (-0.4) mm long. Petals 1.2-1.8 mm long, 1.2-1.4 mm wide, obovate, slightly cupped adaxially, white, spreading; apex rounded, emarginate. Stamens white; filament narrowly ovate, 1.4-1.7 mm long, ca 0.4 mm wide; anther narrowly obovate, 1.4-1.7 mm long, ca 0.4 mm wide, opening by 2 pore-like slits that extend laterally across apex and down adaxial surface of anther sacs, septum between anther sacs intact, the anther sacs 0.3-0.5 mm long. Ovary inferior, 0.9-1.2 mm long, 1.3-1.7 mm wide, the apical appendage ca 0.4 mm high; style 2.8-3.4 mm long, ca 0.4 mm wide, white, straight or slightly curved; stigma 0.4-0.5 mm wide. Berries ca 4 mm in diameter, purple-black, sparsely to moderately pubescent with minute glandular hairs; seeds ca 0.6 mm long, 0.3 mm wide. Fig. 40.

    Habitat and Distribution: Hispaniola: endemic to the Massif du Nord-Cordillera Central where it occurs in broad-leaved cloud forests; 600-1530 m, most common at 1000-1500 m. (Fig. 38).

    Phenology: Collected in reproductive condition from May through February, apparently reaching its peak of flowering from late June through August.

    Taxonomy and Systematics: Mecranium puberulum is a pubescent species with white flowers and anthers that open by means of two slits. Its leaves have five major longitudinal veins and tertiary cross-veins that are impressed above. Mecranium puberulum may be most easily confused with M. ovatum and M. alpestre. All three species have leaves that are approximately the same shape. Mecranium ovatum, endemic to the Sierra de Baoruco of the Dominican Republic, is an essentially glabrous species with leaves very similar in size and vein impression to those of M. puberulum, except that the leaves of M. ovatum only three major longitudinal veins. Mecranium alpestre is endemic to the Massif de la Hotte of Haiti, is pubescent like M. puberulum, but has leaves that are generally much smaller (less than 4 cm long on fertile shoots). Well-developed pseudodomatia, formed by the revolute leaf margin near the petiole, are lacking in M. puberulum, but are often found in M. alpestre.

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