Mecranium crassinerve (Urb.) Skean

  • Family

    Melastomataceae (Magnoliophyta)

  • Scientific Name

    Mecranium crassinerve (Urb.) Skean

  • Primary Citation

    Syst. Bot. Monogr. 39: 50. 1993

  • Basionym

    Ekmaniocharis crassinervis Urb.

  • 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 Sud: Morne La Hotte [Massif de la Hotte, Morne Vanderveld], on steep NE slopes in montane woods, ca 800 m, fl, 10 Jun 1917, Ekman H208 (holotype: S!; isotype: S!).

    Description: Shrub or small tree to ca 2.5 m tall. Twigs slightly 4-angled, soon becoming rounded, 2-3 mm in diameter on internodes, with a prominent collar-like flange, ca 1-3 mm wide, encircling each node and making total nodal diameter 4-7 mm, smooth, essentially glabrous, but youngest buds and nodal ridges often with a few unbranched to irregularly branched and matted multicellular hairs, often hidden beneath nodal flanges; internodes (1-) 2.2-5.4 (-6.8) cm long. Leaf blade 3.4-11 (-12.8) cm long, (1.5-) 2.5-5.4 cm wide, ovate, less commonly elliptic, coriaceous; apex acuminate or acute, often curved downward; base slightly or strongly cordate, less commonly rounded; margin plane, or often revolute near base, obscurely serrate throughout, with teeth terminated by caducous, multicellular, apically-curved, acicular projections to ca 1.5 mm long and 0.2 mm wide at base; venation suprabasal, usually with 1 pair of conspicuous secondary veins joining midvein 1-3 (-5) mm above lamina base, and 1 pair of inconspicuous, intramarginal secondary veins; adaxial surface with midvein, largest pair of secondary veins, and tertiary veins strongly impressed in living material, often flattening upon drying; abaxial surface with midvein and largest pair of secondary veins raised, the intramarginal secondary veins and tertiary veins flat or very slightly raised, the quaternary and higher order veins flat, the surface essentially glabrous, but with scattered minute, glandular hairs; marsupiform domatia and persistent axillary hair tufts absent. Petiole 3-11 mm long, glabrous. Inflorescences borne in leaf axils and on leafless nodes below leaves, 2.5-7.1 cm long, 1.5-3.6 cm wide, 1-2 branched, the caducous bracts to ca 2.1 mm long, rarely these bracts persistent and foliar, with blades to ca 1.9 long, 0.7 cm wide and petioles ca 1 mm long; peduncle (6-) 15-23 (-31) mm long. Hypanthium 2-2.8 mm long, 1.9-2.4 mm wide, cylindrical or very slightly obconical, smooth, very sparsely pubescent with minute glandular hairs; portion free from ovary 0.7-1.2 mm long; portion of calyx bearing external teeth ca 0.4 mm long. Calyx teeth ca 0.5 mm long, 0.4 mm wide, often with caducous acicular apices. Calyptra present in bud, dome-like, with a caducous apiculum to ca 0.1 mm long. Petals 2.1-3.5 mm long, 1.4-1.9 mm wide, obovate, purple, reflexed; apex rounded, emarginate. Stamens red-purple with white anther sacs; filament narrowly obovate, 1.8-2.4 mm long, ca 0.4 mm wide; anther narrowly ovate or oblong, 1.7-2.1 mm long, ca 0.5 mm wide, the anther sacs 1.5-1.8 mm long, opening confluently by a single small apical pore. Ovary inferior, 1.2-1.9 mm long, 1.4-1.8 mm wide, the apical appendage ca 0.8 mm high; style 4.6-5.8 mm long, ca 0.5 mm wide, light red-purple, strongly curved; stigma ca 0.25 mm wide. Immature berries ca 4 mm long, 5 mm wide, green, tinged with red-purple, turning deep purple-black, urceolate, very sparsely pubescent with minute glandular hairs. Immature seeds ca 0.6 mm long, 0.4 mm wide, tan. Mature fruits and seeds not known. Fig. 23.

    Habitat and Distribution: Hispaniola: endemic to low elevation "rak bwa," i.e. hardwood forests on karst, of the Massif de la Hotte of Haiti; 800-905 m. For discussions of the vegetation of this region and localities of populations of this species see Judd (1987), and Skean (1989a). (Fig. 13).

    Phenology: Flowering in June and early July.

    Taxonomy and Systematics: Mecranium crassinerve differs from all other members of the genus in possessing well-developed nodal flanges (Fig. 23B). These stem outgrowths were distinct enough for Urban (1921) to recognize this taxon as Ekmaniocharis crassinervis, representing a monotypic genus commemorating his collaborator, Erik Ekman. Similar nodal outgrowths are found in Miconia, e.g., M. condylata Wurdack, and do not warrant generic recognition, even on phenetic grounds. Mecranium crassinerve is not likely to be confused with any other species. Its distinctive nodal flanges, leaves with impressed veins, and flowers with red-purple petals make it very easy to recognize. The young leaves characteristically bear conspicuous marginal, multicellular, acicular projections (Fig. 23D), which are much less developed in other species of the genus. In dried material of M. crassinerve the leaves are generally olive green above and golden-brown below. The specific epithet refers to the conspicuous nerves in the leaves, which appear especially thickened upon drying. Unfortunately, M. crassinerve may be the species of Mecranium most threatened by extinction. The lower elevation montane forests of the Massif de la Hotte, where this species is endemic, have essentially been destroyed by clear-cutting and burning for cropland and charcoal production (Skean 1989a).

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