Australian Tropical Rainforest Plants - Online edition

Medicosma riparia (P.Royen) T.G.Hartley

Shrub (woody or herbaceous, 1-6 m tall)
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Leaves and flowers [not vouchered]. © G. Sankowsky
Scale bar 10mm. © CSIRO
10th leaf stage. © CSIRO
Cotyledon stage, epigeal germination. © CSIRO

Hartley, T.G. (1985) Australian Journal of Botany 33: 41.


Occasionally grows into a small tree but usually flowers and fruits as a shrub.


Leaf blades about 4.5-7 x 1.5-3.5 cm, petioles about 0.7-1 cm long, channelled on the upper surface. Leaves, petioles and twigs glabrous. Lateral veins forming loops well inside the blade margin. Oil dots numerous and conspicuous, usually visible to the naked eye.


Pedicels nil or very short, up to 1 mm long. Sepals about 4 mm long, apices obtuse. Petals about 20-25 mm long, densely stellate hairy or stellate scaly on the outer surface. Stamens four, about 18-20 mm long alternating with four staminodes which are slightly larger. Anther filaments hairy. Style about 25 mm long, clothed in simple and stellate hairs.


Each flower produces 3 or 4 follicles, each about 8-10 mm long, usually 2 seeds per follicle. Cotyledons orbicular, about 2 mm diam.


Cotyledons elliptic, about 12 x 5 mm, apex truncate, base cuneate to attenuate, margins crenate, petioles very short or absent. Oil dots visible mainly near the margins. First pair of leaves obovate, margins crenate in the upper half. Oil dots visible with a lens. At the tenth leaf stage: leaf blade obovate, apex retuse, base attenuate, margin with a few crenate teeth towards the apex. Lateral veins forming loops inside the blade margin. Midrib raised on the upper surface. Leaves aromatic when crushed. Stems with 2 longitudinal ridges running down from the point of attachment of each petiole. Seed germination time 166 days.

Distribution and Ecology

Occurs in CYP, known only from a few collections made in the McIlwraith Range, Weipa, Iron Range and Bamaga areas. Altitudinal range from near sea level to 150 m. Grows in rain forest, gallery forest and some of the drier types of rain forest. Also occurs in New Guinea.

Coombea riparia van Royen, Nova Guinea 2: 10(1960), Type: van Royen 4709, New Guinea, Irian Jaya, Merauke District, between Boepel and Lake Wam.
RFK Code
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