(L.) L.f.
Description
Abroma augustum (L.) L.f. is a soft-wooded shrub or small tree of tropical and subtropical Asia, ranging from India, Nepal and Myanmar through southern China, Indochina and Malesia to New Guinea and Australia, and widely introduced elsewhere; GBIF documents around 2,078 occurrences across this broad Indo-Pacific span. It favours moist lowland forest margins, riverbanks, secondary thickets and disturbed ground at low elevations. The photographed specimen comes from the Morandi-Khola in lowland Nepal at about 670 m, flowering in October, consistent with its preference for warm, humid foothill habitats.
It is a fast-growing shrub or small tree 2-4 m tall, the young stems, petioles and inflorescence clothed in stellate and stinging-irritant hairs. The leaves are alternate, large, often somewhat dimorphic, the lower broadly ovate-cordate and shallowly 3-5 lobed, the upper smaller and oblong, all with palmate venation. The flowers are showy, pendent and about 3-5 cm across, with five reflexed dark maroon to purplish petals, each bearing a concave nectariferous basal scale, and a staminal tube enclosing five fertile stamens alternating with broad staminodes. The fruit is a distinctive 5-winged, truncate, membranous capsule with longitudinal angles, opening to release numerous small seeds embedded in irritant hairs.
Now placed in Malvaceae (subfam. Byttnerioideae, formerly the segregate Sterculiaceae), Abroma is closely allied to Theobroma and Guazuma. The stem bark yields a strong bast fibre ("devil's cotton") used for cordage, and the bark features in South Asian ethnomedicine as an emmenagogue. Widespread, weedy and often cultivated, the species is of no conservation concern, its success owing to rapid growth, copious wind- and water-dispersed seed, and tolerance of disturbance.
Author: (L.) L.f. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Nepal, Flora Malesiana, Wilkie et al. phylogeny of Byttnerioideae (Malvaceae), Masters treatment of Sterculiaceae in Flora of British India