Mecranium latifolium (Cogn.) Skean

  • Family

    Melastomataceae (Magnoliophyta)

  • Scientific Name

    Mecranium latifolium (Cogn.) Skean

  • Primary Citation

    Syst. Bot. Monogr. 39: 66. 1993

  • Basionym

    Mecranium amygdalinum f. latifolium Cogn.

  • Common Names

    camasey almendre

  • 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: PUERTO RICO. Sierra de Luquillo, Mt. Jimenes, fl, 19 Jun 1885, Sintenis 1568 (holotype: BR!; isotypes: BR! F! G-2! GOET-2! GH! M! MO! S! US!).

    Description: Shrub or small tree to ca 8 m tall. Twigs slightly to moderately 4-angled, 1.5-3 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 0.9-3.4 (-4.5) cm long. Leaf blade 5.4-15.4 cm long, 1.5-4.8 (-5.7) cm wide, ovate, less commonly elliptic; apex acuminate; base cuneate or slightly decurrent; margin plane or slightly revolute, often strongly so near base, obscurely to conspicuously serrate in distal ca 3/4; venation suprabasal, usually with 1 pair of conspicuous secondary veins joining midvein 2-16 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 flat, the surface essentially glabrous, but with scattered minute, glandular hairs, and caducous unbranched to irregularly branched and matted multicellular hairs at axils of junction of midvein and conspicuous secondary veins. Petiole 7-30 mm long, essentially glabrous. Inflorescences borne in leaf axils and on leafless nodes below leaves, 1.5-3.9 cm long, 0.8-3 (-3.9) cm wide, 1-2 branched; peduncle 2-16 mm long. Hypanthium 1.8-2.7 mm long, 2-3.1 mm wide, slightly obconical or subglobose, very sparsely pubescent with minute glandular hairs, the portion free from ovary 0.6-1 mm long; portion of calyx bearing external teeth 0.2-0.5 mm long. Calyx teeth ca 0.3 mm long, 0.3 mm wide. Calyptra present in bud, dome-like, with a caducous apiculum to ca 0.2 mm long. Petals 2-3.4 mm long, 1.3-2.6 mm wide, obovate, slightly cupped adaxially, white, spreading; apex rounded, emarginate. Stamens white; filament narrowly ovate, 1.7-2.6 mm long, ca 0.5 mm wide; anther narrowly obovate, 1.6-2.6 mm long, ca 0.5 mm wide, the anther sacs 0.4-0.7 mm long, opening by a single gaping foramen, septum torn. Ovary inferior, 1-1.7 mm long, 1.3-2 mm wide, the apical appendage 0.4-0.9 mm high; style 3.4-5 mm long, ca 0.5 mm wide, white, straight or slightly curved; stigma ca 0.6 mm wide. Berries ca 5.5 mm in diameter, purple-black, glabrous or with a few minute glandular hairs; seeds 0.6-0.9 mm long, 0.4-0.5 mm wide. Chromosome number: n = 12 (Nevling 1969). Fig. 30A.

    Habitat and Distribution: Puerto Rico and St. Thomas: cloud forests and disturbed areas in the Cordillera Central and Sierra de Luquillo; (400-) 800-1100 m. A single early 19th-century collection is known from St. Thomas (Barbier s.n., P), where the species may now be extinct. For detailed discussions of the vegetation of the montane forests of Puerto Rico see Dansereau (1966) and Gleason & Cook (1926). (Fig 31).

    Phenology: Flowering and fruiting sporadically throughout the year.

    Taxonomy and Systematics: Mecranium latifolium is endemic to Puerto Rico and Saint Thomas, but has not been reported from St. Thomas in recent years. The species is most similar to M. multiflorum of south island Hispaniola and M. septentrionale of the Cordillera Septentrional of Hispaniola, the mountains nearest Puerto Rico. Mecranium latifolium differs consistently from the latter only in having larger flowers (e.g., petals 2-3.4 mm long vs. 1-1.4 mm long). Eggers & Baron (1879) doubted the occurrence of this species, which they listed as M. amygdalinum, on St. Thomas. I have examined a large-leaved Barbier collection from Paris with this general locality indicated on the label. The species may now be extinct there, but its existence at higher elevations is not improbable. Judd (1981) encountered a similar situation with Lyonia rubiginosa (Persoon) G. Don var. rubiginosa, a cloud forest taxon not collected from that island since 1887. Traditionally, this species has been recognized incorrectly under the name M. amygdalinum (see discussion under the latter). Cogniaux (1886) described four forms of M. amygdalinum from Puerto Rico, which he later gave varietal rank (Cogniaux 1891). I have elevated Cogniaux's M. amygdalinum f. latifolium to specific rank. Three of Cogniaux's other forms of M. amygdalinum from Puerto Rico are placed here in synonymy under M. latifolium. Mecranium amygdalinum f. subintegerrimum is lectotypified here because Cogniaux (1886) listed two syntypes in the original publication: Sintenis 280 and Sintenis 280b. I have chosen a specimen of Sintenis 280 at BR as the lectotype of this form. As Cogniaux's names suggest, there is a fair amount of morphological variation within M. latifolium. Plants from the Sierra de Luquillo tend to have larger, broader leaves, and larger flowers and fruits than those from the Cordillera Central. This species is commonly confused with Henriettea macfadyenii (Triana) Alain, a cauliflorous species from Puerto Rico with 4-merous flowers that lack calyptrae. These two species can be differentiated easily, even in vegetative condition. The leaves of H. macfadyenii contain large, elongate "megastyloid" crystals, which are clearly visible under 10x magnification. Large styloids are lacking in Mecranium, a genus with druses. See Baas (1981) and Judd (1989) for discussions of the taxonomic importance of crystals in the axillary-flowered Miconieae. Dent-Acosta (1989) has studied the reproductive biology of this species. See discussion under Phenology. According to Little et al. (1974), this species has as its colloquial name "camasey almendro" or "camasey." Little's listing (under M. amygdalinum) included an illustration of a specimen with extremely broad leaves. A beautiful color engraving of M. latifolium can be found in Richard (1812, plate 36). In this illustration the habit corresponds to material from Puerto Rico, and the 5-merous fruit is undoubtedly based on the original description of Melastoma amygdalina from Hispaniola (see discussion under Mecranium amygdalinum and Desrousseaux 1797).

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