Combretum

"Schousboea" redirects here. As described by H.C.F. Schumacher and Peter Thonning, this is a synonym of Alchornea.

The bushwillows or combretums, Combretum, make up the type genus of the family Combretaceae. The genus comprises about 370 species of trees and shrubs, roughly 300 of which are native to tropical and southern Africa, about 5 to Madagascar, some 25 to tropical Asia and approximately 40 to tropical America. The genus is absent from Australia. Though somewhat reminiscent of willows (Salix) in their habitus, they are not particularly close relatives of these.

Ecology

Bushwillow trees often are important plants in their habitat. Savannahs in Africa, in particular those growing on granitic soils, are often dominated by Combretum and its close relative Terminalia. Other species of this genus are a major component of Southwestern Amazonian moist forests. This genus contains several species that are pollinated by mammals other than bats, which is quite rare indeed.^[1] But most species are more conventionally pollinated by insects or birds.

Typhlodromus combretum, a mite of the family Phytoseiidae, was discovered on a bushwillow plant and is named after this genus. Other herbivores that eat Combretum foliage include the caterpillars of the Brown Awl (Badamia exclamationis) which is found on C. albidum, C. latifolium and C. ovalifolium; those of the Orange-tailed Awl (Bibasis sena) are recorded from C. extensum and C. latifolium.

Use by humans

Several species are used in African or Indian traditional medicine. Combretastatins, found in the South African Bushwillow (C. caffrum) and presumably other species of this genus, are under study for the therapy of tumors, including anaplastic thyroid cancer for which there is little or no approved treatment at present. At least C. molle is also recorded to contain large quantities of punicalagins, the antioxidants well-known from the Pomegranate (Punica granatum), a somewhat related plant. These chemicals, too, are suspected to suppress cancer growth.

The famous botanist George Don studied this genus extensively. The Luvuvhu River in southern Africa was named after the River Bushwillow (C. erythrophyllum), locally known as muvuvhu.

Selected species

References