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Family:

Melastomataceae (Magnoliophyta)

Accepted Name:

This name is currently accepted.

Description:

Description Author and Date: D. Penneys, Oct. 2011, modified from Penneys & Judd, 2005.

Type: Guadeloupe, L. C. M. Richard s.n. (holotype, P!).

Description: Evergreen shrubs or small trees to 5 m high; bark gray to brown, smooth to shallowly, longitudinally fissured; young twigs reddish, becoming brown, usually glabrous, infrequently with a sparse indumentum on youngest growth of inconspicuous, closely adpressed, multicellular, stellate hairs (0.03)0.06 - 0.11(0.13) mm in diameter, these appearing as punctations with age, and twigs soon glabrous; nodes (3.87)4.20 - 6.94(7.50) mm in diameter, usually glabrous or rarely with pubescence similar to that on twigs, the hairs 0.08 - 0.21 mm in diameter. Leaf blade chartaceous to coriaceous, narrowly ovate to elliptic or widely elliptic (narrow obovate), (5.1)8.2 - 13.9(15.6) cm long, (2.7)3.6 - 6.6(8.8) cm wide, ± plane, to curved abaxially and bullate in harsh, exposed environments; apex attenuate to acute (obtuse), the tip long-acuminate (acuminate); base acute to obtuse to rounded (cuneate), sometimes slightly decurrent; adaxial surface of young blades almost glabrous to moderately covered with closely adpressed stellate hairs, rarely with unicellular, uniseriate hairs, mature leaves glabrous, occasionally with very inconspicuous remnants of stellate hairs near base; abaxial surface of young blades densely covered with stellate hairs (0.06)0.08 - 0.22(0.48) mm in diameter, mature leaves glabrous or sometimes retaining stellate to peltate hairs, these becoming reduced and appearing as punctations, yellowish to red or black, often sunken in pits, (0.03)0.08 - 0.18(0.25) mm in diameter; margin plane to occasionally slightly revolute or inrolled in harsh environments, entire or very rarely with higher order veins extending out to margin and creating minute, tooth-like projections; venation basal, the major veins frequently slightly decurrent, with 2 or 3 pairs of secondary veins, and 1 pair of inconspicuous submarginal secondary veins, the tertiary veins (17)22 - 32(34), intergrading with quaternary veins at base and apex. Petiole (1.0)2.0 - 3.8(5.8) cm long, green or reddish, usually glabrous or moderately pubescent, with hairs similar to those on twigs and blades, these evenly distributed on all parts of petiole, the stellate hairs (0.06)0.08 - 0.14 mm in diameter. Inflorescence terminal, cymose, corymbose, (6.9)7.5 - 12.5(25.9) cm long, (3.9)4.6 - 8.8(15.5) cm wide, with 3 - 5 orders of branching, the caducous bracts to ca 2.0 cm long; peduncle (0.8)1.2 - 3.4(6.2) cm long, first internode above peduncle (1.6)1.8 - 3.7(7.6) cm long, first lateral internode (2.2)2.3 - 4.3(7.5) cm long, the flowers (24)33 - 82(194) per inflorescence. Pedicels (2.74)4.67 - 7.63(14.13) mm long, glabrous or with stellate hairs (0.05)0.08 - 0.14(0.16) mm in diameter. Hypanthium (3.67)3.9 - 4.34(4.60) mm long as measured from base to torus, (3.26)3.47 - 4.07(4.34) mm wide, the indumentum of stellate hairs, dense near pedicel attachment, progressively sparser approaching calyx lobes, these (0.06)0.08 - 0.16(0.19) mm in diameter, the portion of hypanthium free from ovary (0.97)1.28 - 1.44(1.53) mm long; inner hypanthium smooth to granular textured, occasionally with indistinct longitudinal ridges, torus to calyx apex length (1.25)1.28 - 2.0(2.07) mm, torus to calyx notch length (0.09)0.16 - 0.56(0.88) mm. Calyx lobes (0.63)0.91 - 1.63(1.97) mm long, (2.32)2.69 - 3.74(4.34) mm wide, lobes broadly triangular, the apex sometimes acute, the indumentum similar to that of hypanthium, the external calyx teeth (0.22)0.25 - 0.72(1.07) mm long, hemispherical to bluntly pyramidal with apex directed upwards. Petals yellow, yellow-cream, yellow-orange, to pink or crimson, often with buff margins below adjacent overlapping petal, irregularly very broadly ovate to orbiculate (3.67)5.75 - 7.63(8.13) mm long, (4.67)4.88 - 7.07(8.38) mm wide. Stamens (9.0)9.5 - 10.5(11.0) mm long; filaments cream, 6.6 - 7.7 mm long, with proximal filament segment (0.78)0.99 - 1.19(1.30) mm wide, distal segment (0.53)0.64 - 0.83(1.03) mm wide; anthers yellow or cream, (2.32)2.50 - 3.07(3.29) mm long, (0.60)0.64 - 0.78(0.83) mm wide, longitudinal slits (2.00)2.10 - 2.50(2.75) mm long. Ovary (2.29)2.38 - 2.82(3.16) mm long, (1.60)1.85 - 2.50(2.79) mm wide, style cream, (7.63)10.50. - 13.0(13.75) mm long, (0.56)0.68 - 0.88(0.94) mm wide. Berries 4 - 6 mm in diameter. Seeds 0.58 - 0.83 mm long, 0.33 - 0.40 mm wide. See Figs. 1, 2, 7, 9.

Habitat and Distribution: Charianthus corymbosus ranges throughout the middle Lesser Antilles on the relatively large islands of Guadeloupe, Dominica and Martinique (Fig. 9) where it is often found in great abundance in tropical lower montane to montane rain forests - especially in disturbed areas, clearings, roadsides and along rivers. Primary elevational distributions of C. corymbosus are from 500 to 1,000 meters in Guadeloupe, 550 to 800 meters in Dominica, and 500 to 850 meters in Martinique.

Phenology: Charianthus corymbosus has been collected in reproductive condition nearly throughout the year in Guadeloupe and Dominica. In Guadeloupe, reproduction apparently is reduced in January, May, June, and October, while in Dominica the reproductive cycle is primarily restricted to January through June. In Martinique, C. corymbosus has been found in reproductive condition from November through May.

Taxonomy and Systematics: Charianthus corymbosus has, on average, the smallest flowers in the genus and also seems to produce less nectar than the other species. In light of the propensity for apomixis and self-compatibility in the Miconieae, this is an intriguing combination of characteristics, especially in consideration of the vast population that occupies the region between the Pitons du Carbet, Morne Jacob and Mont Pelée on Martinique. Research on the reproductive biology of this species is needed. Hodge (1941) described three varieties of Charianthus corymbosus, which were later rejected by Howard (1989) and included, without nomenclatural recognition, within this variable species. As intermediates can be found within populations, and trends dependent upon environmental factors such as exposure to wind and sun are apparent, Howard’s broad concept of the species is supported here. Charianthus corymbosus hybridizes with C. dominicensis in the region of the Freshwater Lake, Dominica.