Melastoma L.

Scientific Description

Family Melastomataceae.

Habit and leaf form. Small trees, or shrubs. Young stems often tetragonal. Helophytic, or mesophytic. Leaves opposite; sometimes somewhat turgescent; petiolate (petiole short to moderate); simple. Leaf blades entire; lanceolate, or oblong, or ovate; elliptic, or ovate; 3–7 -nerved (with conspicuous parallel cross veins); palmately veined and parallel-veined (no dominant midrib, the several strong veins diverging at the base, converging at the apex); cross-venulate. Leaves without stipules. Leaf blade margins entire, or serrate. Leaves without a persistent basal meristem. Stem anatomy. Secondary thickening absent, or developing from a conventional cambial ring, or anomalous; from a single cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present, or absent. Nectar secretion from the perianth, or from the androecium. Entomophilous, or ornithophilous, or cheiropterophilous.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; compact in cymes. The terminal inflorescence unit cymose. Inflorescences distally axillary, or terminal; in great variety, usually panicled or contracted cymes. Flowers pedicellate; bracteate; bracteolate; operculate (calyptrate), or not operculate; regular, or somewhat irregular. The floral asymmetry involving the androecium. Flowers 3–5(–6) merous; tetracyclic, or pentacyclic. Free hypanthium present; campanulate, or urceolate; often moderately to densely covered with scales or hairs. Perianth with distinct calyx and corolla; 10–14; 2 -whorled; isomerous. Calyx present; 5–7; 1 -whorled; gamosepalous; entire, or lobed; lobulate, or blunt-lobed, or toothed; calyptrate, or not calyptrate; imbricate, or valvate, or contorted, or open in bud; regular; not persistent. Corolla present; 5–7; 1 -whorled; polypetalous; contorted; regular; white, or red, or pink, or purple. Petals obovate. Androecial members definite in number. Androecium 10–14. Androecial members free of the perianth; all equal (rarely), or markedly unequal; free of one another; 1 -whorled, or 2 -whorled. Stamens 10–14; all more or less similar in shape (rarely), or distinctly dissimilar in shape; diplostemonous; inflexed in bud; filantherous. Anthers basifixed; non-versatile; dehiscing via pores; initially tetrasporangiate; appendaged, or unappendaged. Gynoecium (4–)5(–6) carpelled. The pistil 5 celled. Gynoecium syncarpous; eu-syncarpous; superior, or partly inferior, or inferior. Ovary plurilocular; usually 5 locular. Epigynous disk absent. Gynoecium stylate. Styles 1; apical. Stigmas 1. Placentation axile. Ovules (2–)6–50 per locule; anatropous.

Fruit and seed features. Fruit fleshy to non-fleshy (coriaceous); dehiscent; a capsule. Capsules splitting irregularly. Fruit 20–100 seeded. Seeds non-endospermic; small. Embryo well differentiated (but minute). Cotyledons 2. Micropyle zigzag.

Special features. Larger stamens with a distinct connective prolongation.

Etymology. From the Greek for "black" and "mouth, face"; said to refer to the berries staining the mouth dark purple when eaten; the fruit of some species has purple pulp.