Taxon Details: Mecranium purpurascens (DC.) Triana
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Family:
Melastomataceae (Magnoliophyta)
Melastomataceae (Magnoliophyta)
Scientific Name:
Mecranium purpurascens (DC.) Triana
Mecranium purpurascens (DC.) Triana
Primary Citation:
Trans. Linn. Soc. London 28(1): 139. 1871
Trans. Linn. Soc. London 28(1): 139. 1871
Accepted Name:
This name is currently accepted.
This name is currently accepted.
Synonyms:
Ossaea purpurascens DC.
Miconia ossaeiformis Naudin
Clidemia ossaeiformis (Naudin) Cogn.
Sagraea ossaeiformis (Naudin) Triana
Ossaea purpurascens DC.
Miconia ossaeiformis Naudin
Clidemia ossaeiformis (Naudin) Cogn.
Sagraea ossaeiformis (Naudin) Triana
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: JAMAICA. High mountains, without specific locality [Blue Mtns.], without date [1785-86], Swartz s.n. (holotype G-DC, IDC microfiche 2562!; isotypes: S! S-in part!).
Description: Shrub or small tree to ca 7 m tall. Twigs slightly to moderately 4-angled, 1-2 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 0.9-2.9 (-4.5) cm long. Leaf blade 2.3-8 cm long, 1.1-3.4 cm wide, obovate or elliptic, less commonly narrowly ovate, coriaceous; apex acuminate; base cuneate or slightly decurrent; margin obscurely serrate in distal ca 3/4, but often appearing entire because slightly revolute; venation basal or suprabasal, usually with 1 pair of conspicuous secondary veins joining midvein 1-4 (-9) 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 usually slightly raised, the surface essentially glabrous, but with some scattered minute, glandular hairs; marsupiform domatia sometimes present on abaxial surface in axils at junction of midvein and largest pair of secondary veins, persistent axillary hair tufts absent. Petiole 5-17 mm long, glabrous. Inflorescences borne in leaf axils and on leafless nodes below leaves, 1.7-6.8 cm long, 0.7-3.9 cm wide, 1-2 branched; peduncle 8-29 (-39) mm long. Hypanthium 2.7-3.7 mm long, 2.4-4.1 mm wide, slightly obconical or subglobose, very sparsely pubescent with minute glandular hairs, the portion free from ovary 0.9-1.6 mm long; portion of calyx bearing external teeth 0.3-0.9 mm long. Calyx teeth ca 0.25 mm long, 0.25 mm wide. Calyptra present in bud, dome-like, with a caducous apiculum to ca 0.3 mm long. Petals 3.3-4.2 mm long, 1.7-3.1 mm wide, obovate, white or pink-tinged, slightly cupped adaxially, often reflexed; apex rounded, emarginate. Stamens white; filament elliptic or narrowly ovate, 1.9-3 mm long, 0.5-0.8 mm wide; anther elliptic or slightly obovate, 1.8-3.2 mm long, 0.4-0.7 mm wide, the anther sacs 1.3-2.2 mm long, opening by a single small apical pore. Ovary inferior, 1.6-2.5 mm long, 1.1-2.7 mm wide, the apical appendage 0.6-1.2 mm high; style 4.2-7.2 mm long, 0.4-0.7 mm wide, white, often strongly curved; stigma 0.2-0.4 mm wide. Berries ca 7 mm in diameter, purple-black, glabrous or with a few minute glandular hairs; seeds ca 0.8 mm long, 0.5 mm wide. Fig. 41.
Habitat and Distribution: Jamaica: endemic to broad-leaved cloud forests in higher elevations of the Blue Mountains; (1070-) 1250-2250 m. (Fig. 42).
Phenology: Flowering primarily from August through October, with fruits produced through February.
Taxonomy and Systematics: Mecranium purpurascens is a glabrous species with white or pink-tinged petals and elliptic or slightly obovate anthers that open by means of a small apical pore. It can be differentiated quite easily from the other two Jamaican species, M. virgatum and M. axillare (see Appendix 3). Mecranium virgatum is a glabrous species with larger flowers that are borne exclusively on old wood below the leaves, and which have hypanthia with prolonged bases and anthers that open by a gaping foramen. Mecranium axillare has smaller flowers, and in the taxon sympatric with M. purpurascens, M. axillare subsp. axillare, the leaves bear tufts of hairs on their abaxial surfaces at the junction of the midvein and the two largest secondary veins. In vegetative condition, plants of M. purpurascens are often mistaken for the terminal-flowered species, Miconia rubens (Swartz) Naudin and M. theaezans (Bonpland) Cogniaux, other Miconieae of the high elevations of the Blue Mountains. Upon close examination (at 20x or higher magnification), the abaxial surfaces of dried leaves of M. purpurascens have their smallest veinlets raised, unlike these Miconia species. In populations of M. purpurascens on the high ridges of Blue Mountain Peak (above 1975 m) there are individuals, especially at East Peak, with narrow leaves and abaxial marsupiform domatia. These individuals intergrade with broader-leaved individuals lacking such domatia. Proctor (1972) thought that these plants might represent an undescribed species intermediate between M. purpurascens and "M. amygdalinum" (=M. axillare). A specimen having features of M. purpurascens and M. axillare is known from a single collection (Proctor 9980; IJ, NY) made in the John Crow Mountains 1.5-2 mi SW of Ecclesdown at elevations of 1500-2000 ft [460-610 m]. The specimen is vegetatively similar to M. purpurascens, and has pink-petaled flowers that are approximately the same size as those of M. axillare (hypanthium ca 1.7 mm long, 1.7 mm wide; petals ca 2.3 mm long, 1.4 mm wide). This collection may represent a hybrid or an undescribed species.
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: JAMAICA. High mountains, without specific locality [Blue Mtns.], without date [1785-86], Swartz s.n. (holotype G-DC, IDC microfiche 2562!; isotypes: S! S-in part!).
Description: Shrub or small tree to ca 7 m tall. Twigs slightly to moderately 4-angled, 1-2 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 0.9-2.9 (-4.5) cm long. Leaf blade 2.3-8 cm long, 1.1-3.4 cm wide, obovate or elliptic, less commonly narrowly ovate, coriaceous; apex acuminate; base cuneate or slightly decurrent; margin obscurely serrate in distal ca 3/4, but often appearing entire because slightly revolute; venation basal or suprabasal, usually with 1 pair of conspicuous secondary veins joining midvein 1-4 (-9) 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 usually slightly raised, the surface essentially glabrous, but with some scattered minute, glandular hairs; marsupiform domatia sometimes present on abaxial surface in axils at junction of midvein and largest pair of secondary veins, persistent axillary hair tufts absent. Petiole 5-17 mm long, glabrous. Inflorescences borne in leaf axils and on leafless nodes below leaves, 1.7-6.8 cm long, 0.7-3.9 cm wide, 1-2 branched; peduncle 8-29 (-39) mm long. Hypanthium 2.7-3.7 mm long, 2.4-4.1 mm wide, slightly obconical or subglobose, very sparsely pubescent with minute glandular hairs, the portion free from ovary 0.9-1.6 mm long; portion of calyx bearing external teeth 0.3-0.9 mm long. Calyx teeth ca 0.25 mm long, 0.25 mm wide. Calyptra present in bud, dome-like, with a caducous apiculum to ca 0.3 mm long. Petals 3.3-4.2 mm long, 1.7-3.1 mm wide, obovate, white or pink-tinged, slightly cupped adaxially, often reflexed; apex rounded, emarginate. Stamens white; filament elliptic or narrowly ovate, 1.9-3 mm long, 0.5-0.8 mm wide; anther elliptic or slightly obovate, 1.8-3.2 mm long, 0.4-0.7 mm wide, the anther sacs 1.3-2.2 mm long, opening by a single small apical pore. Ovary inferior, 1.6-2.5 mm long, 1.1-2.7 mm wide, the apical appendage 0.6-1.2 mm high; style 4.2-7.2 mm long, 0.4-0.7 mm wide, white, often strongly curved; stigma 0.2-0.4 mm wide. Berries ca 7 mm in diameter, purple-black, glabrous or with a few minute glandular hairs; seeds ca 0.8 mm long, 0.5 mm wide. Fig. 41.
Habitat and Distribution: Jamaica: endemic to broad-leaved cloud forests in higher elevations of the Blue Mountains; (1070-) 1250-2250 m. (Fig. 42).
Phenology: Flowering primarily from August through October, with fruits produced through February.
Taxonomy and Systematics: Mecranium purpurascens is a glabrous species with white or pink-tinged petals and elliptic or slightly obovate anthers that open by means of a small apical pore. It can be differentiated quite easily from the other two Jamaican species, M. virgatum and M. axillare (see Appendix 3). Mecranium virgatum is a glabrous species with larger flowers that are borne exclusively on old wood below the leaves, and which have hypanthia with prolonged bases and anthers that open by a gaping foramen. Mecranium axillare has smaller flowers, and in the taxon sympatric with M. purpurascens, M. axillare subsp. axillare, the leaves bear tufts of hairs on their abaxial surfaces at the junction of the midvein and the two largest secondary veins. In vegetative condition, plants of M. purpurascens are often mistaken for the terminal-flowered species, Miconia rubens (Swartz) Naudin and M. theaezans (Bonpland) Cogniaux, other Miconieae of the high elevations of the Blue Mountains. Upon close examination (at 20x or higher magnification), the abaxial surfaces of dried leaves of M. purpurascens have their smallest veinlets raised, unlike these Miconia species. In populations of M. purpurascens on the high ridges of Blue Mountain Peak (above 1975 m) there are individuals, especially at East Peak, with narrow leaves and abaxial marsupiform domatia. These individuals intergrade with broader-leaved individuals lacking such domatia. Proctor (1972) thought that these plants might represent an undescribed species intermediate between M. purpurascens and "M. amygdalinum" (=M. axillare). A specimen having features of M. purpurascens and M. axillare is known from a single collection (Proctor 9980; IJ, NY) made in the John Crow Mountains 1.5-2 mi SW of Ecclesdown at elevations of 1500-2000 ft [460-610 m]. The specimen is vegetatively similar to M. purpurascens, and has pink-petaled flowers that are approximately the same size as those of M. axillare (hypanthium ca 1.7 mm long, 1.7 mm wide; petals ca 2.3 mm long, 1.4 mm wide). This collection may represent a hybrid or an undescribed species.