Mecranium septentrionale Skean

  • Family

    Melastomataceae (Magnoliophyta)

  • Scientific Name

    Mecranium septentrionale Skean

  • Primary Citation

    Syst. Bot. Monogr. 39: 94. 1993

  • 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. Santiago-Puerto Plata Boundary: Cordillera Septentrional, Pico Diego de OCampo, 1135 m, Skean 1799 (holotype: FLAS!; isotypes: A! BM! BR! F! FLAS! G! IJ! JBSD! NY! P! S! US!).

    Latin diagnosis: Species haec a M. multifloro thecis brevioribus (0.3-0.7 vs. 0.8-1.2 mm) differt.

    Description: Shrub or small tree to ca 8 m tall. Twigs slightly to moderately 4-angled, 1.5-2.5 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 1-3.8 (-6.7) cm long. Leaf blade 3.3-5.7 (-11.8) cm long, 1.2-2.9 (-4.2) cm wide, ovate, less commonly elliptic; apex acuminate; base cuneate or slightly decurrent; margin plane or slightly revolute, often strongly so near base, conspicuously serrate in distal ca 3/4; venation suprabasal, usually with 1 pair of conspicuous secondary veins joining midvein 1-7 mm above lamina base, and 1 pair of inconspicuous, intramarginal secondary veins; adaxial surface with midvein and largest pair of secondary veins flat or slightly impressed, the intramarginal secondary veins and tertiary veins flat or not visible; 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, and caducous unbranched to irregularly branched and matted multicellular hairs at axils of junction of midvein and conspicuous secondary veins. Petiole 7-11 (-21) mm long, essentially glabrous. Inflorescences borne in leaf axils and on leafless nodes below leaves, 1.4-2.5 cm long, 0.6-1.2 cm wide, 1-2 branched, the caducous bracts to ca 1.3 mm long; peduncle 4-8 mm long. Hypanthium 1.1-1.7 mm long, 1.2-1.4 mm wide, slightly obconical or subglobose, very sparsely pubescent with minute glandular hairs, the portion free from ovary 0.5-0.6 mm long; portion of calyx bearing external teeth 0.1-0.2 mm long. Calyx teeth ca 0.15 mm long, 0.15 mm wide. Calyptra present in bud, dome-like, with a caducous apiculum to ca 0.15 mm long. Petals 1-1.4 mm long, 0.7-0.9 mm wide, obovate, slightly cupped adaxially, white, spreading; apex rounded, emarginate. Stamens white; filament narrowly ovate, 1-1.2 mm long, 0.3-0.4 mm wide; anther narrowly obovate, 1.1-1.2 mm long, ca 0.5 mm wide, the anther sacs 0.3-0.7 mm long, opening by a single gaping foramen, septum torn. Ovary inferior, 0.8-1.2 mm long, 0.9-1 mm wide, the apical appendage 0.3-0.4 mm high; style 2.7-2.9 mm long, ca 0.3 mm wide, white, straight or slightly curved; stigma ca 0.4 mm wide. Berries ca 3 mm in diameter, purple-black, glabrous or with a few minute glandular hairs; seeds 0.6-0.7 mm long, 0.4-0.5 mm wide. Fig. 30B.

    Habitat and Distribution: Dominican Republic: known only from the region of Pico Diego de OCampo, the highest point (1249 m) in the Cordillera Septentrional of Hispaniola, where it occurs in broad-leaved cloud forest; 1100-1249 m. Common melastome associates include Miconia dielsiana Urban, Miconia septentrionalis W. Judd & R. Beaman, and Leandra limoides (Urban) W. Judd & Skean. The forest on Pico Diego de OCampo is extremely disturbed below ca 1140 m. Zanoni (1990) has published a floristic study of this area. (Fig. 38).

    Phenology: Flowering and fruiting from March to September.

    Taxonomy and Systematics: Mecranium septentrionale can be distinguished easily from M. acuminatum, the other species of Mecranium known from the Cordillera Septentrional. The latter lacks a calyptra, has leaves with marsupiform domatia, and is not known from Pico Diego de OCampo. Of Hispaniolan species, M. septentrionale may be most easily confused with M. multiflorum from the Massif de la Salle-Sierra de Baoruco. Both taxa lack strongly impressed tertiary veins and abaxial tufts at the two major vein intersections. However, the anther sacs of M. multiflorum are consistently longer than those of M. septentrionale (0.3-0.7 vs. 0.8-1.2 mm). Mecranium septentrionale is also very similar to M. latifolium, a species endemic to Puerto Rico). Generally, flowering shoots of M. latifolium have wider leaves and larger flowers than those of M. septentrionale (see Key), but there is some overlap in leaf width. Flower size, especially as reflected in petal length, appears to be the most important characteristic differentiating these two species. The petals of M. septentrionale are 1-1.4 mm long, while those of M. latifolium are 2-3.4 mm long.

  • Sorry, no descriptions available for this record.