Pacific Island Ecosystems at Risk (PIER)

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Ossaea marginata
(Desr.) Triana, Melastomataceae
No images for this taxon


Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Other Latin names:  Clidemia marginata (Desr.) DC.; Melastoma marginata Desr.; Pentossaea marginata (Desr.) Judd

Habit:  shrub

Description: 

Genus [as Pentossaea]: "Evergreen subshrubs or shrubs with pleonanthic shoots; twigs more or less terete, nodose, glabrous to densely strigose, with a ridge encircling each node; druse crystals present. Indumentum of conspicuous, unbranched, slender to stout, strigose, multicellular hairs with or without glandular apices and of minute, multicellular, glandular hairs (or sometimes glandular-stellate hairs) occurring on stems, leaves, inflorescence axes, and hypanthia, or in some species more or less restricted to reproductive parts. Buds narrowly ovoid, sylleptic, usually densely pubescent. Leaves opposite, decussate, petiolate to nearly sessile, estipulate, herbaceous to cariaceous, more or less plane; adaxial surface essentially glabrous (at maturity) or sparsely to densely covered with unbranched, elongate, multicellular hairs and sometimes also with minute glandular hairs (especially in vein impressions or at petiole junction); abaxial surface usually sparsely to densely covered with slender to stout, unbranched, elongate, multicellular hairs along with minute glandular to glandular-stellate, multicellular hairs (i.e., glandular hairs unbranched or sparsely branched with one branch glandular and the others nonglandular), sometimes only with glandular hairs and becoming more or less glabrous with age; domatia not observed in vein axils, margin serrate in distal ca. 3/4 of lamina to entire, plane to slightly revolute near base, the teeth ending in an elongate multicellular hair (and often associated with additional elongate hairs); venation acrodromous, slightly suprabasal, with a prominent midvein, 1-4 pairs of secondary veins (1 of these often intramarginal and inconspicuous), numerous percurrent tertiary veins more or less perpendicular to midvein and reticulate to orthogonal quaternary and higher-order veinlets; petiole caniculate, essentially glabrous to densely strigose-pubescent. Inflorescences axillary cymes (occasionally reduced and more or less fasciculate) borne in the leaf axils and in a few species on leafless nodes below the leaves, usually borne singly, rarely 2 per axil, bracteate, with opposite, narrowly triangular to ovate or oblong bracts (the 2 lowest protecting the inflorescence in bud and quickly caducous). Flowers perfect, 5- or 6-merous, sessile. Hypanthium more or less cylindrical, abaxially with conspicuous, unbranched, elongate hairs with or without glandular apices, intermixed with minute glandular or glandular-stellate-hairs, adaxially glabrous or with a few hairs around apex. External calyx lobes 5 or 6, conspicuous, elongate, terete. Internal calyx lobes 5 or 6, distinct (noncalyptrate), more or less triangular, with obtuse, acute, to acuminate apices. Petals 5 or 6, more or less white, narrowly triangular with acute apices,1-veined, glabrous or occasionally with a single dorso-apical projection (hair), rarely with a few glandular hairs. Stamens 10-12, more or less isomorphic, glabrous, geniculate, inserted at apex of hypanthium, androecial fringe lacking; filament narrowly ovate to oblong, flattened dorsally; anther narrowly ovate to oblong, sometimes slightly curved, the 2 anther sacs dehiscing confluently by means of a single small apical pore, the connective sometimes slightly prolonged beyond the bases of the anther sacs. Ovary inferior or nearly so, 3-5-locular, with axile placentation and numerous ovules, the apex occasionally prolonged into several blunt appendages surrounding the style. Style cylindrical, more or less straight; stigma capitate, papillose. Berries red to blue, with indumentum similar to hypanthium. Seeds small, rounded- to angular-obovate, the testa smooth to slightly roughened" (Judd, 1989; p. 490).

Species: "Low, herbaceous, pubescent, perennial, with ovate-lancolate five-nerved leaves 10-14 cm long.  Cymes few-flowered on short peduncles from the leaf-axils.  Calyx and receptacle densely hairy.  Fruit dark purple, the size of a pea."  (Jour. Linn. Soc. Lond., 1937; 51:291).

Habitat/ecology:  An invader of wet forests on Mauritius (Lorence and Sussman, 1988).

Propagation:  Seed

Native range:  Brazil (Bosser et al., 1990; p. 10)

Presence:

Pacific Rim
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Japan
Japan
Japan (country)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 258)
Indian Ocean
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Mauritius
Mautitius Islands (Mauritius and Rodrigues)
Mauritius Island introduced
invasive
Cronk, Q. C. B./Fuller, J. L. (2001)
Mauritius
Mautitius Islands (Mauritius and Rodrigues)
Mauritius Island introduced
invasive
Lorence, D./Sussman, R. W. (1988) (pp. 187-204)

Comments:  A problem species on Mauritius.


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This page was created on 1 JAN 1999 and was last updated on 20 OCT 2006.