Currajong, Tasmanian Hemp-bush
Tasmanicher HanfMalvaceae Info (Home)
Asterotrichion Gallery
Introduction
Asterotrichion is a monotypic genus of Malvaceous shrubs, endemic to Tasmania. The name is a reference to the stellate hairs (trichomes) which cover many parts of the plant. It is one of several Malvaceous plants to which the Aboriginal name currajong is applied, others including species of Brachychiton, Franciscodendron, Sterculia and Commersonia (in these cases under the spelling kurrajong). Otherwise it is known as the Tasmanian Hemp-bush, in reference to the use of the bark as a source of fibre.
Classification
The genus was introduced by Klotzsch in 1841. His type species, Asterotrichion sidoides, is invalidly named, as Hooker's description of it as Sida discolor, preceded Hooker's use of Plagianthus sidoides for the same plant. Melville introduced the valid combination Asterotrichion discolor in 1966.
Asterotrichon N.T. Burb. is an orthographic variant. Blepharanthemum Klotzsch is a synonym.
Asterotrichion is related to the Australian endemic genera Gynatrix and Lawrencia, and the New Zealand endemic genera Hoheria and Plagianthus, these genera collectively forming the Plagianthus alliance grouping within the tribe Malveae and subfamily Malvoideae. On grounds of shared morphology I conjectured that Gynatrix was the most closely related genus. Subsequent DNA sequence studies [6] place the genus in a trichotomy with Gynatrix and Plagianthus.
Asterotrichion discolor (Hook.) Melville
Currajong, Tasmanian Hemp-bush
Tasmanicher Hanf
Asterotrichion discolor is an arching shrub, or sometimes a small tree, typically growing to 2m in height. The young branches, the underside of the leaves and the inflorescence are more or less covered with a whitish or brown stellate indumentum, composed of both sessile and stalked hairs. The leaves are lanceolate and finely serrate, 5-8 cm, rarely 10cm, long, and ¼th as wide, glabrous and dark green above, with impressed veins, and pale green below. They are technically palmately nerved, as the first pair of lateral veins arise from the base of the blade, but they are no more prominent that subsequent lateral veins, and appear pinnately nerved to a casual inspection.
Asterotrichion discolor is usually dioecious, i.e. bearing male and female flowers on different plants, but is occasionally monoecious, i.e. bearing male and female flowers on a single plant. In common with other species in the Plagianthus alliance the flowers lack an epicalyx. The delicately scented flowers are present from late autumn to late winter. They are small and borne in short axillary racemes, which are dense and spike-like in the males, and drooping and looser in the females. The male flowers have a broad campanulate calyx. Their staminal column bears around 15 stamens indistinctly divided into 5 clusters, each filament being approximately along the same length as the column. The pistil is small and barren. In the female flowers the calyx is almost tubular. The staminal column has 5 sessile staminodes. The ovary is 2 celled. There are two style branches, which are hairy towards their base, and much dilated from the middle upwards. The indehiscent fruit is enclosed with the calyx; it has pubescent papery surface, and is usually single-seeded.
It is to be found in ravines, especially in the northern parts of Tasmania.
Seed of Asterotrichion discolor is available commercially.
The bark has been used as a fibre source for cordage.
Images
Synonyms: Synonyms of Asterotrichion discolor include Asterotrichion sidoides Klotzsch, Blepharanthemum sidoides (Hook.) Klotzsch, Napaea sidoides Alef., Plagianthus discolor (Hook.) Asch., Plagianthus limpenii Booth ex Lindl., Plagianthus sidoides Hook. and Sida discolor Hook.
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© 2001, 2003, 2006 Stewart R. Hinsley