Australian Tropical Rainforest Plants - Online edition

Xanthostemon formosus Peter G.Wilson

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Flowers. © B. Gray
Scale bar 10mm. © CSIRO
10th leaf stage. © CSIRO
Cotyledon stage, epigeal germination. © CSIRO

Wilson, Peter G. (1990) Telopea 3(4): 462. Type: Cook District: Portion 49V, Portion of Alexandra, Cooper Creek, 16 10 S, 145 25 E, Gray 3366, 26.iv.1984 (NSW). ISOTYPES: QRS.


Hard, slightly darker, brittle stripes in the blaze.


Leaves crowded and almost forming whorls on sections of the twigs. Leaf blades about 12-22 x 2-4.5 cm. Midrib depressed on the upper surface. Oil dots pale brown, visible with a lens if not visible to the naked eye.


Calyx tube (hypanthium) glabrous, about 5 x 20 mm, divided into five saccate, nectariferous depressions. Calyx lobes glabrous, triangular, about 10 mm long. Petals glabrous, +/- orbicular, about 18 mm diam. Staminal filaments green, about 20-25 mm long, each inserted in an orifice in the base of the anther, anthers about 4 mm long. Ovary glabrous, surrounded by the calyx tube (hypanthium) and attached to it by five radiating ribs. Ovary about 5-6 mm diam, placentas peltate. Style green, about 25 mm long. Stigma small and terminal.


Fruits +/- globular, about 12-20 x 12-20 mm (excluding the long persistent calyx at the base), style persistent at the apex. Seeds flat, about 4-5 mm diam. Embryo +/- ovate-orbicular, about 3-4 mm diam. Radicle curved.


Cotyledons orbicular, 6-8 mm diam. Oil dots small, numerous, more visible about the margin. At the tenth leaf stage: leaves narrowly obovate or elliptic, apex acute, base attenuate, upper surface with a few pale hairs towards the base; oil dots small, visible with a lens; petiole and stem clothed in pale brown hairs. Seed germination time 13 to 20 days.

Distribution and Ecology

Endemic to NEQ, restricted to a few creeks between the Daintree River and Cape Tribulation. Altitudinal range quite small, from near sea level to 100 m. Grows as a rheophyte along rocky or bouldery creeks flowing through rain forest.

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