Miconia rigidissima Urb. & Ekman

Description

Description Author and Date: Walter S. Judd, 2010, based on Judd, W. S. (2007). Revision of Miconia sect. Chaenopleura (Melastomataceae) in the Greater Antilles. Systematic Botany Monographs 81:1-235.

Type: HAITI. Dept. de L’Ouest: Massif de la Selle, Morne La Visite, open slopes on limestone, ca 1700 m, fl bud, 11 Aug 1924, E. L. Ekman H1425 (holotype: S!; isotypes: EHH, NY!, US!).

Description: Shrub to 1.5 m tall. Indumentum of multicellular, pale to moderately ferrugineous, irregularly stellate-branched hairs forming a thick, dense, and tangled mat due to their interwoven, irregularly bent, and elongate arms. Young twigs not ridged, ± rectangular in cross-section, 2-5 mm wide, becoming terete with age, the indumentum of dense, ferrugineous, irregularly stellate-branched hairs, forming an appressed, tangled mat; internodes 0.5-3.5 cm long. Leaves with petiole 2-7 mm long, the indumentum similar to that of stem; blade 1.8-7.1 cm long, 0.4-1.7 cm wide, ovate or elliptic to oblong, often narrowly so, flat to slightly V-shaped, very coriaceous, the apex acute, the base acute to rounded, the margin nearly plane to clearly revolute, nearly entire, obscurely serrulate, slightly undulate, or conspicuously undulate-crenate, especially distally, ca 9-100% of margin entire, the largest teeth 0.1-0.3 mm long; venation acrodromous, ± basal to slightly suprabasal, with prominent midvein and 2 conspicuous secondary veins placed 0.5-2 mm in from margin, and numerous percurrent tertiary veins oriented subperpendicular to midvein, the tertiary veins connected by 1 to few quaternary veins, and the higher order veins ± orthogonal-reticulate, but higher order veins ± obscure due to thick indumentum and coriaceousness of lamina; adaxial surface green, initially with scattered hairs but very quickly glabrescent, the midvein impressed, secondary veins slightly impressed to flat, tertiary veins very slightly impressed to flat, and higher order veins flat, the surface appearing wrinkled after drying, with scattered druse crystals; abaxial surface pale ferrugineous to ferrugineous, densely covered with irregularly stellate-branched hairs forming a thick, dense, and tangled mat due to their interwoven, irregularly bent, and elongate branches, the midvein prominently raised, secondary veins raised, tertiary veins slightly raised, and higher order veins usually slightly raised-reticulate, all but midvein ± obscured by dense indumentum. Inflorescences many-flowered paniculate to spicate cymes of 2 to 4 branch pairs, 1.3-4.7 cm long, 1.2-2.7 cm across; proximal segment of lowermost inflorescence branches 1-5 mm long, distal internodes of inflorescence branches shorter, ultimate branches very reduced, not apparent and flowers, thus, in dense, ± globose clusters, with dense, tangled mat of irregularly stellate-branched hairs; peduncle 0.4-2.5 cm, with similar indumentum; each inflorescence branch associated with deciduous, but often ± persistent due to dense packing of inflorescence branches, ovate or ovate-triangular to elliptic (or slightly obovate) bract, ca 3-10 mm long, 2.3-4.5 mm wide, the apices acute, the lower pair sometimes leaf-like; flowers in dichasia, each subtended by 2 deciduous (but usually persistent due to dense packing of flowers), ovate to obovate bracteoles 2.5-6 mm long, 1.5-3 mm wide, the indumentum of dense, matted, ± irregularly stellate hairs, their apices acute to obtuse. Flowers ± sessile. Hypanthium cylindrical, free portion ca 1-1.4 mm long, the outer surface with dense, matted and intertwined, ± irregularly stellate hairs, the inner surface glabrous and slightly 10-ridged (or sometimes also with very inconspicuous ridges separating major ridges), the apices of the ridges not projecting or slightly projecting, to 0-0.07 mm. External calyx lobes 5, 0.6-1.2 mm long, 1.4-1.9 mm wide, ± triangular, with acute to acuminate apex, indumentum of dense mat of tangled, interwoven, ± irregularly stellate-branched hairs; internal calyx lobes 5, 0.6-1.2 mm long, 1.4-1.9 mm wide, triangular to ovate-triangular, green, with dense, tangled ± irregularly stellate hairs, the apex rounded to obtuse, the margin entire, but may have a fringe of hairs; calyx tube 0.2-0.4 mm long. Petals 5, 2.8-3.3 mm long, 2.2-2.9 mm wide, broadly ovate to nearly orbicular, glabrous, white; margin entire. Stamens 10, geniculate; proximal segment 2.2-2.7 mm; distal segment 2.7-3.2 mm long, with minute dorsal projection, the anther 1.6-2.2 mm long, with fertile portion of anther sacs 1.5-1.8 mm long, the connective/distal part of filament extended 0.9-1.5 mm beyond the base of the anther sacs. Ovary 3-loculate, 1/2-4/5-inferior, 2-3 mm long, 2.3-2.5 mm in diameter, but appearing as broad as 3 mm due to dense matted stellate hairs (on outer surface of hypanthium), short-ovoid or ovoid to obovoid, apically glabrous and slightly ridged, with fluted apical projection to 0.45-1.4 mm encircling the base of style; style 3.8-5 mm long, glabrous; stigma truncate. Berries 4.5-5 mm long, 4.5-5.2 mm in diameter [slightly immature], ± globose, probably turning blue at maturity, with ± dense tangled hairs. Seeds 0.65-1.1 mm long, angular-obovoid; testa smooth. Fig. 49, 50.

Habitat and Distribution: Hispaniola (Haiti), Massif de la Selle, from the Morne La Visite/Pic Cabaio region west to the vicinity of Pic La Selle; in open, steep, limestone slopes in windswept moist, dwarfed cloud forests or open forests of Pinus occidentalis and Agave antillarum Desc.; 1700-2575 m. Associated melastomes include Miconia domingensis, M. lanceolata, and M. luteola. The vegetation of the Morne La Visite/Pic Cabaio region (part of the Pic National Morne La Visite) is described in detail by Judd (1987), while that in the vicinity of Pic La Selle is described in Judd & Sanders (1986); see also Holdridge (1947).

Phenology: Flowering period is poorly documented, but possibly in flower from February through September.

Taxonomy and Systematics: Miconia rigidissima is a member of the crisped-hair clade (see discussion under M. lanceolata), and is most closely related to M. viscidula and M. macayana. The characters distinguishing M. rigidissima from M. viscidula are summarized in the discussion under that species. Miconia rigidissima may be the sister species of M. macayana, and the two share the putative apomorphy of undulate to undulate-crenate or crenate leaf margins and extremely coriaceous leaves. Miconia rigidissima is easily distinguished from M. macayana by its leaves with smaller crenations, i.e., the largest 0.1-0.3 mm (vs. 0.7-2 mm), only 2 secondary veins (vs. 4 secondaries), and acute to rounded (vs. rounded to cordate) bases, the petals 2.8-3.3 mm long (vs. ca 2.6 mm), and the 3-loculate (vs. 5-loculate) ovaries that are 2-3 mm (vs. ca 1.1 mm) long. The species occurs only in the high elevation forests of the Massif de la Selle, and is thus geographically isolated from M. macayana, which is endemic to the highest elevations of the Massif de la Hotte.

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Miconia rigidissima: Botanical line drawing. (image/jpeg)