Mecranium alpestre Urb. & Ekman

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: Massif de la Hotte, western group, near Torbec, top of Morne Formon in shrubby, broad-leaved forest, 2225 m, fr, 1 Jan 1927, Ekman H7476 (holotype S!; isotypes: EHH! G! IJ! NY! US!).

Description: Shrub or small tree to ca 3.5 m tall. Twigs slightly to moderately 4-angled, 1-2 mm in diameter, smooth, youngest portions rather uniformly covered with unbranched to irregularly branched and matted, often flattened and scale-like, multicellular hairs; internodes 0.7-1.8 cm long. Leaf blade 1.3-3.8 cm long, 0.8-2.1 cm wide, ovate or elliptic, coriaceous; sprout leaves and sucker-shoots with internodes to 3.4 cm long and leaves with blades to 7.5 cm long, 5.7 cm wide; apex short-acuminate or acute, less commonly obtuse to rounded or slightly retuse; base obtuse or rounded; margin obscurely serrate in distal ca 3/4, usually flat except strongly revolute base occasionally forming basal pseudodomatia; venation basal, usually with 1 pair of conspicuous secondary veins joining midvein 0-1 mm above lamina base, and 1 pair of inconspicuous, intramarginal secondary veins; adaxial surface with midvein and largest pairs of secondary veins slightly to strongly impressed, the intramarginal secondary veins and tertiary veins flat; abaxial surface with midvein and largest pair of secondary veins raised, the intramarginal secondary veins and tertiary veins flat or slightly raised, the quaternary and higher order veins usually slightly raised, the surface pubescent with hairs similar to those on stem concentrated along veins and scattered minute, glandular hairs; persistent axillary hair tufts present. Petiole 2-8 mm long, pubescent like stem; petioles of sprouts and sucker-shoots to 21 mm long. Inflorescences borne in leaf axils and on leafless nodes below leaves, 1-4.5 cm long, 0.8-2.2 cm wide, 1-2 branched; peduncle 6-14 mm long. Immature hypanthium ca 1.3 mm long, 1.7 mm wide, broadly urceolate or subglobose, sparsely pubescent with minute glandular hairs, the portion free from ovary ca 0.5 mm long; portion of calyx bearing external teeth ca 0.3 mm long. Immature calyx teeth ca 0.2 mm long, 0.2 mm wide. Calyptra present in bud, dome-like. Immature petals ca 1.3 mm long, 1.2 mm wide, obovate, slightly cupped adaxially, white; apex rounded, emarginate. Immature folded stamens white; filament narrowly ovate, ca 1.0 mm long, 0.5 mm wide; anther narrowly obovate, ca 1.2 mm long, 0.4 mm wide, the anther sacs ca 0.4 mm long, apparently opening by a single gaping foramen, septum torn. Immature ovary inferior, ca 1.0 mm long, 1.2 mm wide, the apical appendage ca 0.3 mm high; immature style ca 1.3 mm long, 0.3 mm wide, white, straight; stigma ca 0.6 mm wide. Immature berries ca 4 mm in diameter, red-purple, glabrous or sparsely pubescent with minute glandular hairs; immature seeds ca 0.8 mm long, 0.4 mm wide. Fig. 16.

Habitat and Distribution: Hispaniola: endemic to broad-leaved cloud forests in the high elevations of the Massif de la Hotte of Haiti, where it is known only from the ridge of Morne Formon; 2140-2225 m. See Judd (1987) for detailed species lists and a discussion of the mosaic of cloud forests and pine forests found on Morne Formon. (Fig. 17).

Phenology: Probably flowering in September and October, and producing mature fruits by March.

Taxonomy and Systematics: Mecranium alpestre is a small-leaved pubescent species with white flowers and anthers that open by means of a gaping foramen. It is known only from collections of specimens bearing flower buds, immature fruits, and some fragmentary floral material. The description above is based on a single flower bud collected just before anthesis, and some dried anthers. The flower bud is illustrated in Fig. 16H. Mecranium alpestre is most similar to M. tricostatum, a small-leaved and relatively glabrous species with abaxially raised veinlets and conspicuous pseudodomatia located on the leaf bases. Both taxa are sympatric on Morne Formon in the Macaya Biosphere Reserve. I have observed M. alpestre with flower buds in July and August, with M. tricostatum starting to flower, and with slightly smaller immature fruits than M. tricostatum in January. It is quite possible that these two species are isolated reproductively by flowering time, with M. tricostatum flowering first.

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Mecranium alpestre: Botanical line drawing. (image/jpeg)