Geography and distribution
Caloncoba welwitschii occurs in Nigeria, Cameroon, Gabon, Democratic Republic of Congo, Congo (Congo Brazzaville), Tanzania, Malawi, and Mozambique.
Kew expeditions to Mozambique
Kew botanists, including Tim Harris and Jonathan Timberlake, have recently been on expeditions to Mozambique, during which specimens of Caloncoba welwitschii were collected.
Overview: A tree up to 14 m tall, with large leaves (about 25 cm long and 18 cm wide), having a petiole (leaf stalk) up to 15 cm long.
Leaves: The stipules (leaf-like structures) found either side of the petiole base are up to 2.5cm long and sometimes fall off soon after the leaf is fully formed.
Flowers: The showy, scented flowers are borne on older wood and are up to 10 cm in diameter. Each flower has about 10 white, papery petals and many stamens (male parts). The stamens are held in a cluster around the centre of the flower, and are up to 2 cm long. The style (female part) is about 1 cm long.
Fruits: The fruit is about 8 cm across, covered in slender spines, and splits into 5 or 6 sections when mature.
Seeds: The numerous, spherical seeds are about 6 mm in diameter.
Kew's research on this species
Kew scientists Sue Zmarzty and Mark Chase, are working on C. welwitschii and a group of plants closely related to it, in partnership with botanists at the National Herbarium of the Netherlands (Wageningen).
They are investigating evidence, some of it from molecular studies (comparing the DNA of various species), that although C. welwitschii belongs to the family Achariaceae, some plants that look very similar may actually belong to a different plant family: the Salicaceae. The Salicaceae includes the willows (such as golden weeping willow) and poplars, as well as many tropical and subtropical plants.
Caloncoba welwitschii has a wide range of traditional medicinal uses in Central Africa. For example, the leaves and bark are used for treating rheumatism, and are made into poultices for applying to abscesses. The leaf-sap is used to treat headaches, and the plant itself is prescribed as a means of killing body-lice. The fruit pulp is eaten in Gabon. It has been reported that the seed oil is used to treat leprosy in the Democratic Republic of Congo.
Caloncoba welwitschii is sometimes cultivated as a medicinal plant in tropical Africa.
This species at Kew
Both dried and alcohol-preserved specimens of Caloncoba welwitschii are held in Kew’s Herbarium and made available to bona fide researchers by appointment. The details of some of these specimens, including images, can be seen online in Kew’s Herbarium Catalogue.
View details and images of specimens
The Economic Botany Collection at Kew includes specimens of Caloncoba welwitschii wood that can be examined by researchers by appointment.