Tristemma mauritianum

Family

Melastomataceae

Botanical Name

Tristemma mauritianum J.F.Gmel.

Gmelin, J.F. (1791) Systema Naturae: 693. Type: Mauritius, Commerson s.n.; holo: P. Fide H. Jacques-Felix, Bull. Mus. Hist. Nat. (Paris) ser.3, no. 418, Bot. 28: 137 - 207 (1976).

Synonyms

Tristemma virusanum Comm. ex A.Juss., Genera Plantarum: 329(1838), Type: ?.

Common name

Tristemma

Weed

Stem

Usually flowers and fruits as a shrub about 1 m tall.

Leaves

Leaf blades 3-nerved, about 5-15 x 3-7 cm. Both the upper and lower surfaces of the leaf blade clothed in simple, +/- prostrate hairs. Each leaf with a midrib and two major longitudinal veins plus two other longitudinal veins which could nearly be regarded as intramarginal veins. Petiole bases joined by a definite line running across the twigs.

Flowers

Hypanthium with two or three rings of hairs towards the apex. Calyx lobes about 3-6 mm long. Petals about 6-10 mm long. Stamens ten, +/- uniform, each with a pair of glands on the filament slightly below the anther, filaments normally bent where the glands are attached. Anthers with a terminal pore.

Fruit

Fruit about 10 x 6 mm, calyx persistent at the apex. Fruit fleshy, splitting irregularly. Seeds immersed in a whitish pulp. Seeds small, about 0.6 mm long, cochleate, testa tuberculate.

Seedlings

Cotyledons small, about 1.5-2 x 1.5-2 mm. Hypocotyl terete but the stem above the cotyledons 4-angled with erect hairs on each angle. First pair of true leaves triplinerved with a few white hairs scattered on the surface. At the tenth leaf stage: leaf blade with a midrib and two major longitudinal veins plus two other longitudinal veins which could nearly be regarded as intramarginal veins. Upper and lower surfaces clothed in pale prostrate hairs. Stem hairy, shortly 4-winged.

Distribution and Ecology

An introduced species, originally from western and central Africa and Madagascar, now naturalized in NEQ particularly in the Innisfail-Babinda area. Altitudinal range from near sea level to 550 m. Grows along roads and in disturbed areas in well developed lowland and upland rain forest.

Natural History

This species was probably introduced because of its showy pink flowers. The introduction was probably effected by a family from Mauritius who settled in the Frenchman Creek area in 1883.