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Family:

Melastomataceae (Magnoliophyta)

Primary Citation:

Ann. Sci. Nat., Bot. ser. 3, 16: 197. 1851

Accepted Name:

This name is currently accepted.

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: JAMAICA. [Blue Mtns], locality not specified. O. Swartz s.n. (holotype: S, digital image seen; isotypes: B, xerographic copy of specimen seen, BM!, SBT, digital image seen).

Description: Shrub or small tree to 7 m tall. Indumentum of multicellular, minute-globular to appressed/matted and ± irregularly stellate-branched hairs, these usually ephemeral or degrading, rarely with long-stalked, gland-headed hairs to 2 mm long. Young twigs rectangular to square in cross-section, 1.5-4 mm wide, non-ridged or with 4 inconspicuous to conspicuous flanges, 2 extending below each point of petiole attachment, rarely with a pair of gland-like globular structures on each side of petiole-base at node, with sparse to moderate, minute-globular to appressed/matted and ephemeral/degrading, irregularly branched hairs, usually ± glabrescent, rarely also with sparse to dense, long-stalked, gland-headed hairs (populations near Ecclesdown, John Crow Mts.); internodes 0.7-4.8 cm long. Leaves with petiole 7-43 mm long, the indumentum of sparse to moderate, minute-globular to appressed and ephemeral/degrading branched hairs, and rarely also with long-stalked, gland-headed hairs; blade 3.2-19.1 cm long, 1.3-4.5(-5) cm wide, ovate (to elliptic), V-folded along midvein and falcate (to nearly flat), coriaceous, the apex acuminate, the base (cuneate) acute to rounded, the margin entire or irregularly undulate to obscurely serrulate distally, ca 28-100% of margin entire, the largest teeth (if present) ca 0.1 mm long, slightly revolute (thus leaves appearing entire even when a few distal teeth are present); venation acrodromous, ± basal, with prominent midvein and 4 secondary veins, with 2 conspicuous secondary veins placed 1.5-6.5 mm in from margin, and 2 inconspicuous secondary veins closer to margin, and numerous percurrent tertiary veins oriented subperpendicular to midvein, the tertiary veins separated by composite inter-tertiary veins or joined by 1 to several quaternary veins, the higher order veins orthogonal-reticulate; adaxial surface greenish when dry, ± glabrous, but initially with appressed (rarely erect), irregularly branched hairs, these quickly caducous or degenerating, the midvein and major secondary veins impressed, minor secondary veins and tertiary veins very slightly impressed to flat, higher order veins flat, the surface appearing wrinkled-papillose when dry due to presence of scattered druse crystals; abaxial surface light green with veins sometimes red tinged, sparsely to moderately with minute-globular hairs to appressed/matted and ± irregularly stellate-branched hairs, the latter usually ephemeral or degrading, rarely also with elongate and irregularly branched hairs along major veins, the midvein and major secondary veins ± prominently raised, the minor secondary and tertiary veins very slightly raised to flat, and higher order veins flat.

Description (cont.): Inflorescences paniculate cymes of (2-) 3 to 7 major branch-pairs (each of which is cymosely branched), 3-16.5 (-21.5) cm long, 2-9 (-11) cm across; proximal segment of lowermost inflorescence branches 0.6-4.6 (-6) cm long, distal internodes of inflorescence branches shorter, ultimate branches 0-0.3 mm long, with minute-globular to usually appressed, degenerating/ephemeral, irregularly stellate-branched hairs (rarely also with long-stalked, gland-headed hairs); peduncle 1.5-6.5 cm long, with similar indumentum; each inflorescence branch associated with a quickly caducous, narrowly ovate or elliptic to ± oblong bract, ca 2.2-8.6 (-22) mm long, 0.5-2.5 (-3) mm wide, the apices ± acute, the lowermost pair sometimes leaf-like; flowers in dichasia, in 3-flowered glomerules, each subtended by 2 quickly caducous, narrowly triangular to ovate or oblong to ± linear bracteoles, 1.4-2.9 mm long, 0.4-1.1 mm wide, with indumentum of minute-globular to appressed branched hairs, their apices acute. Flowers with pedicel ca 0-0.8 mm long. Hypanthium cylindrical, free portion 0.8-1.1 mm long, the outer surface sparsely to moderately covered with minute-globular to appressed/matted, irregularly stellate-branched hairs, the latter usually somewhat degenerating and/or partially deciduous (occasionally persisting and erectly branched), the inner surface glabrous and slightly 10-ridged, the apices of the ridges not extending beyond rim. External calyx lobes 5, 0.3-0.7 mm long, 1.1-1.6 mm wide, ± triangular, with acute to acuminate apex, glabrous or with sparse minute-globular to branched hairs; internal calyx lobes 5, 0.6-1.4 mm long, 1.1-1.6 mm wide, triangular to ovate-triangular, pale green to red, glabrous or with very sparse branched hairs, the apex rounded, the margin entire or minutely erose (due to short, non-branched hairs), calyx tube 0.3-0.5 mm long (occasionally slightly tearing, ca 0.1-0.2 mm). Petals 5, broadly 2.5-3 mm long, 2-2.3 mm wide, ovate to elliptic, glabrous, white; margin entire. Stamens 10, geniculate; proximal segment 2.1-2.5 mm long, distal segment 2.4-3.1 mm long, with minute dorsal projection, the anther 1.1-1.9 mm long, with fertile portion of anther sacs 0.9-1.5 mm long, the connective/distal part of filament extended 0.6-1.6 mm beyond the base of the anther sacs. Ovary 3-loculate, ca 4/5 to 3/4-inferior, 1.5-2.1 mm long, 1.8-2.5 mm in diameter, obovoid, glabrous and ridged, with fluted apical projection ca 0.15-0.3 mm long encircling base of style; style 3.3-8.6 mm long; stigma ± truncate. Berries 4-6 mm in diameter, globose to subglobose, pale blue, but red when immature, glabrous or nearly so. Seeds 0.8-1.2 mm long, angular-obovoid; testa ± smooth to slightly and minutely roughened. Fig. 29.

Habitat and Distribution: Jamaica, Blue Mountains (incl. Port Royal Mts.) and the John Crow Mountains; cloud forests, moist to dry southern slope forests, and disturbed habitats; 730-2250 m. Associated species include Blakea trinerva (Sw.) Triana, Clidemia erythropogon DC., C. umbellata, Conostegia montana (Sw.) DC., C. procera (Sw.) DC., Mecranium axillare (Macfad.) Skean subsp. proctori Skean, M. purpurascens (DC.) Triana, M. virgatum (Sw.) Triana, Meriania purpurea (Sw.) Sw., M. leucantha (Sw.) Sw., Miconia dodecandra (Desr.) Cogn., M. rigida, M. rubens (Sw.) Naudin, M. tetrandra (Sw.) D. Don ex G. Don, M. theazans (Bonpl.) Cogn., Ossaea [= Leandra] asperifolia (Naudin) Triana, and Sagraea crossosepala (Griseb.) Triana. These forests are described in more detail in Shreve (1914) and Tanner (1986).

Phenology: Species collected in flower throughout the year.

Taxonomy and Systematics: Miconia quadrangularis is most closely related to M. stenobotrys, M. krugii, and M. samanensis: the falcate-leaved clade. Synapomorphies supporting this clade are the leaf blades V-shaped and falcate, tertiary veins separated by composite intertertiary veins and not raised abaxially, and mature leaves more or less glabrescent, with only minute globular hairs. Miconia quadrangularis may be the sister species to the other members of the falcate-leaved clade, which have inflorescence bracts and bracteoles that are only tardily deciduous, and thus are present on the upper inflorescence branches when the flowers on the lower branches are at anthesis. In addition, the inflorescences of M. guadrangularis are composed of three-flowered glomerules, while the flowers of M. stenobotrys, M. krugii, and M. samanensis are well separated, in three-flowered dichasia. In addition, Miconia quadrangularis may be distinguished from M. stenobotrys by the lack of pouch-domatia, shorter inflorescences, the primary axis with 2-7 major branch-pairs and these cymose (vs. elongate, with 3-13 major branch-pairs, each of which is raceme-like), shorter hypanthia, i.e., 0.8-1.1 mm long (vs. 1.1-1.7 mm long), and smaller ovaries, i.e., 1.5-2.1 mm long (vs. 2-2.8 mm long); from M. krugii by its non-grooved but often 4-flanged stems, leaves not turning yellow upon drying, with appressed/matted more or less irregularly stellate-branched hairs, along with minute globular hairs, at least when young (vs. glabrescent, with only minute globular hairs), and pale blue (vs. white) berries; and from M. samanensis by its often 4-flanged (vs. non-flanged) stems, slightly 10-ridged (vs. 20-ridged) inner hypanthial surface, smaller petals, i.e., 2.5-3 mm long, 2-2.3 mm wide (vs. 2.9-4.1 mm long, 2.5-3.3 mm wide), and smaller ovaries, i.e., 1.5-2.1 mm long (vs. 2.4-3.8 mm long). The leaves of M. samanensis are often pink to red tinged, even on the lamina, while those of M. quadrangularis are green, with at most only the major veins red-tinged abaxially. Miconia quadrangularis is reproductively isolated from these three species because it occurs on Jamaica, while the others occur in the Cordillera Central of Hispaniola. High elevation populations of Miconia quadrangularis usually have slightly smaller leaves and inflorescences. Plants of the John Crow Mountains have scattered long-stalked, gland-headed hairs on their stems, leaves, and inflorescence axes (in addition to minute-globular to irregularly stellate-branched hairs), whereas those of the Blue Mountains always lack such hairs. These plants have been described as M. quadrangularis var. glandulosa by Proctor (1967). These populations are not given taxonomic recognition because the distribution of such hairs is not considered to be a reliable differentiation characteristic. Many other Antillean species of sect. Chaenopleura, e.g. M. adenocalyx, M. coniophora, M. cubensis, M. ferruginea, M. krugii, M. rigida, M. samanensis, and M. stenobotrys, also vary in the presence of long-stalked glandular hairs. Additional collecting in the John Crow Mountains will likely show that the presence or absence of stalked glandular hairs varies within populations, as it does in the above listed species, some of which are closely related to M. quadrangularis.