Tetraberlinia bifoliolata (ekaba)
Tetraberlinia bifoliolata is a tropical African tree with yellow flowers and explosive seed pods.
About this species
A member of the pea and bean family (Leguminosae) or Fabaceae sensu APG III (2009), Tetraberlinia bifoliolata is a lowland rainforest tree from Africa. It is slowly growing and used locally for timber. It benefits from a relationship with fungi around its roots, which help it to take up water and nutrients.
Geography & Distribution
Tetraberlinia bifoliolata is native to the western and central part of the lower Guinea forest. It occurs in southwestern Cameroon, Equatorial Guinea, Gabon, southwestern Congo, Angola and western Democratic Republic of Congo. In the centre of its distribution, T. bifoliolata may be common with numerous individuals growing together (gregariously), but towards the limits of its distribution, it becomes rare.
A small to large forest tree, Tetraberlinia bifoliolata grows to 5–50 m tall. The leaves each bear a single pair of leaflets.
Flowers are arranged in conspicuous, branched flowering structures composed of many individual flowers (compound inflorescences). Each flower is small and has five petals, one of which is much larger than the other four. The large petal is lemon-yellow, becoming white to pinkish towards the base. The other petals are pale yellow to white.
The pods (fruits) are oblong and flat, measure up to 15 cm long and 7 cm wide and have a distinct nerve running lengthways just above the midpoint of each face of the pod. A second nerve is sometimes present. The pods typically contain one or two seeds, which are released with force at maturity, the pod opening rapidly to expel them.
It is estimated from studies of the closely related species, T. moreliana, that the seeds would be thrown up to 60 m from the parent tree. Despite this apparently impressive distance, it takes several decades to go from establishment of a seedling to a fully mature tree.
Threats & Conservation
Tetraberlinia bifoliolata is relatively widely distributed in tropical Africa, and its wood is mainly used locally for timber. However, timber from the closely related T.tubmaniana from Liberia is traded internationally, and the species is assessed as Vulnerable according to IUCN Red List criteria. As the two species are likely to have similar wood properties, it can be expected that in future T. bifoliolata could be threatened by increased exploitation.
The timber is mainly used locally for buildings, furniture, cabinet making and for plywood. Small amounts of Tetraberlinia bifoliolata timber are exported.
This species at Kew
Pressed and dried specimens of Tetraberlinia bifoliolata are held in Kew’s Herbarium where they are available to researchers by appointment.
A specimen of its wood and bark and a chopping board from Cameroon made from the wood of T. bifoliolata and other species are held in the Economic Botany Collection in the Sir Joseph Banks Building and are available to researchers by appointment.
Symbiotic relationships with fungi
Tetraberlinia bifoliolata can form symbiotic relationships (in which both partners benefit) with several species of ectomycorrhizal fungi (fungi that grow around the root cells of a plant) such as Lactarius chromospermus, Lactifluus gymnocarpoides and Russula meleagris. Ectomycorrhizal fungi develop their symbiotic relationships with plants (often trees) by forming a sheath around the root tips that allows the fungus to absorb organic compounds from the plant whilst taking up water and nutrients for the host plant.
Many other tropical African trees from the pea and bean family (Leguminosae), such as Berlinia razzifera, Isoberlinia doka and Gilbertiodendron dewevrei, are also thought to form ectomycorrhizal relationships with fungi.
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