Mecranium amygdalinum (Desr.) C.Wright
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Family
Melastomataceae (Magnoliophyta)
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Scientific Name
Mecranium amygdalinum (Desr.) C.Wright
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Primary Citation
Anales Acad. Ci. Méd. Habana 5: 435. 1869
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Basionym
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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: [HISPANIOLA] "SAINT DOMINGUE." Without specific locality [probably Haiti, Massif de la Selle], fl, without date [1789], Martin s.n. (holotype: P, not seen; isotype: P(Herb. Poiret)!).
Description: Shrub or small tree to ca 3.5 m tall. Twigs slightly to moderately 4-angled, 1-2 mm in diameter, smooth, essentially glabrous or youngest portions with scattered light brown globular to irregularly branched hairs, especially on nodal ridges; internodes 0.8-1.8 (-3) cm long. Leaf blade 3.9-11.2 cm long, 1.1-2.3 cm wide, membranaceous or coriaceous, narrowly ovate, often red-tinged and plicate if plant in full sun; apex acuminate; base obtuse or acute to slightly decurrent; margin plane or often revolute near base, usually conspicuously serrate in distal ca 4/5; venation usually suprabasal, with 1 pair of conspicuous secondary veins joining midvein 0.5-9 mm above lamina base, and 1 pair of inconspicuous, intramarginal secondary veins; adaxial surface with midvein and 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 some scattered minute, glandular hairs; marsupiform domatia present on abaxial surface in axils at junction of midvein and largest secondary veins, persistent axillary hair tufts absent. Petiole 4-19 mm long, pubescent with hairs similar to those on stem. Inflorescences borne in leaf axils and on leafless nodes below leaves, 1.2-3 cm long, 0.4-2.8 cm wide, 1-2 branched, the caducous bracts to ca 1 mm long; peduncle 2-12 mm long. Hypanthium 1.8-3 mm long, 1.4-1.8 mm wide, slightly obconical, very sparsely pubescent with minute glandular hairs, the portion free from ovary 0.6-1.25 mm long; portion of calyx bearing external teeth 0.2-0.4 mm long. Calyx teeth 0.2-0.4 mm long, ca 0.2 mm wide. Calyptra absent. Petals 2.5-3.8 mm long, 1.6-2.1 mm wide, ovate or obovate, usually appearing ovate due to involute margin, white, with ca 5 major longitudinal veins, strongly reflexed; apex obtuse, emarginate. Stamens white; filament narrowly obovate, 1.2-2.1 mm long, 0.4-0.5 mm wide; anther narrowly ovate, 1.6-2.2 mm long, 0.4-0.6 mm wide, the anther sacs 1.3-2 mm long, opening by a single small apical pore. Ovary 1/2-2/3 inferior, 1.2-1.9 mm long, 1-1.4 mm wide, the apical appendage 0.5-0.8 mm high; style 3.9-6.7 mm long, 0.4-0.7 mm wide, white, strongly curved; stigma 0.2-0.7 mm wide. Berries ca 5 mm in diameter, purple-black, glabrous or with a few minute glandular hairs, apical ovary appendage often prolonged beyond body of fruit; seeds ca 0.5 mm long, 0.3 mm wide. Figs. 14, 15A.
Habitat and Distribution: Hispaniola: primarily a south island species limited to the Massif de la Selle of Haiti, low-elevation collections from north of the Cul de Sac-Enriquillo Depression in ruderal areas around Santo Domingo in the Dominican Republic; in disturbed areas in low to mid-elevation montane broad-leaved and pine forests; 100-1150 m, most common at 500-900 m. (Fig. 13).
Phenology: Flowering and fruiting from February to September.
Taxonomy and Systematics: Traditionally, most authors have considered Mecranium amygdalinum to represent an extremely variable species found on all four Greater Antillean Islands. Careful study of the original description and type specimens from P has revealed that M. amygdalinum is actually a Hispaniolan endemic. In contrast, the widespread polymorphic species complex, treated by most authors as M. amygdalinum, is here treated as five different species, which, if lumped, would correctly be called M. multiflorum. In 1789, Joseph Martin, a Paris-trained plantsman, then director of the Botanical Garden in French Guiana, gathered specimens that were later described by Desrousseaux (1797) in Lamarck and Poiret's Encyclopédie as Melastoma amygdalina and Melastoma multiflora (see Jiménez 1985; Moscoso 1943). Both species were probably collected in the Massif de la Selle-Sierra de Baoruco, most likely in the Massif de la Selle near what is now Port-au-Prince, Haiti. All eight Martin Melastomataceae collections from Saint Domingue cited in the Encyclopédie are species commonly found in the Massif de la Selle, and one, Melastoma ferruginea Desrousseaux [=Miconia ferruginea (Desrousseaux) de Candolle], is endemic to the Massif de la Selle. The type of Melastoma amygdalina I observed from "Herb. Poiret" is unlabeled as to collector, but is labeled "isotype." The type of Melastoma multiflora I observed is labeled as a Martin collection. Today the species represented by these specimens, i.e., what I am treating as Mecranium amygdalinum and M. multiflorum, are known to occur together only in the Massif de la Selle near Port-au-Prince. Desrousseaux (1797) described Melastoma multiflora as a glabrous species with panicles of small, numerous flowers borne in the leaf axils and on the nude part of the branches. He also stated that the flowers had short, obtuse petals. His next entry for the Encyclopédie, was a description of Melastoma amygdalina, which he compared with the preceding species. According to Desrousseaux, the melastome with leaves like almond was similar to M. multiflora, but had more nodose stems, plicate, red-tinged, smaller leaves, and fewer flowers that each had 5 calyx teeth. Desrousseaux's description corresponds to what I am treating as M. amygdalinum, except for the mistaken observation of 5-merous flowers. Mecranium amygdalinum is 4-merous like all other true axillary-flowered melastomes on Hispaniola. As in Desrousseaux's description, Mecranium amygdalinum has leaves that are generally smaller than those of M. multiflorum (1.1-2.3 vs. 1.3-3.4 mm wide), which under intense sunlight become much more heavily tinged with red-purple than those of M. multiflorum. Mecranium amygdalinum also has smaller inflorescences than M. multiflorum (1.2-3 vs. 1.6-4.4 cm long), and the plants are generally fewer-flowered. Figure 15 shows Mecranium amygdalinum and M. multiflorum growing in the Massif de la Selle of Haiti. Note that M. amygdalinum (Fig. 15A) has smaller, plicate leaves and fewer flowers than M. multiflorum (Fig. 15B).
Taxonomy and Systematics (cont.): The major problem in the typification of M. amygdalinum is the species' similarity to M. acuminatum. The two can be differentiated only by petal characters (see Key), and petals are missing from Desrousseaux's description and from the isotype of Melastoma amygdalina that I examined from the Poiret Herbarium. However the sheet probably comes from the Massif de la Selle, where M. acuminatum is not known to occur. Mecranium amygdalinum and M. acuminatum show a rather strong geographical separation (Fig. 13). Mecranium amygdalinum is primarily a south island plant, nearly endemic to the Massif de la Selle, but known north of the Cul de Sac from two collections (Ekman H124280, Lavastre 2095) in heavily disturbed areas near Santo Domingo where it is perhaps a recent immigrant. On the other hand, M. acuminatum is widespread on the north island, but is known south of the Cul de Sac in the Sierra de Baoruco from only one collection (Howard 12073). Though there is a slight overlap in the geographical distributions of these two species, they are not known to occur together and no overlap in petal width has been observed. Ekman (1930) reported the presence of M. amygdalinum on Ile de la Gonave, off the coast of Haiti, near Port-au-Prince. I have seen no specimen of Mecranium from this satellite island, however, the presence of M. amygdalinum there would not be surprising. Mecranium amygdalinum has also been confused with M. plicatum, a more pubescent species with much broader leaves that is known only from the type (in immature fruit), collected in the Massif de la Hotte of Haiti (see Fig. 39).
- Sorry, no descriptions available for this record.
