General Info

Unarmed Tree is up to 20m high. Bipinnate, sparse leaves have closely ranked leaflets. White to yellow bisexual Flowers are in half-spherical heads. Stamens exserted. Fruit is a large flat, straight pod.

Description

Tree

Albizia forbesii.

RSA Tree No. 154.

Common names: Broad-pod, False-thorn, Broad-pod Albizia.

Family: Fabaceae or Leguminosae (Pea, bean or legume family). After the Orchidaceae and the Asteraceae, the Fabaceae is the third largest Angiosperm (flowering plants) family with 700+ genera and close to 20 000 species. Local genera include Acacia (Vauchellia, Senegalia), Albizia, Bauhinia, Bolusanthus, Burkea, Calpurnia, Colophospermum, Cyclopia, Erythrina, Erythrophleum, Faidherbia, Indigofera, Philenoptera and Schotia. The Fabaceae are recognisable by their fruit and by their pinnately compound Leaves. Leaves may also be simple and usually have stipules – some of which may be spinescent. Leaflets are usually entire. Flowers are bisexual and bracteate. Regular flowers usually have 4-5 sepals and the same number of petals. Irregular flowers have 4-5 sepals and 5 or less petals. Stamens have anthers that have 2 pollen sacs and there are usually at least twice the number of stamens as petals – often 10. The superior Ovary has one locule that may contain 1 or more ovules. The Stigma and Style are simple. The single carpel develops into the Fruit, which is usually a pod. The pod dehisces on both sides and may break into segments. Seeds vary.

Name derivation: Albizia – after naturalist Filppo degli Albizzi (18 century) who introduced a species into Europe. forbesii after the Englishman, John Forbs, who collected the type specimen in Mozambique (1822-1823). There are 11 indigenous species of the genus Albizia in southern Africa.

Conservation Status: L C. (Least Concern). 2009 (Raimondo et al.).

Description. This unarmed (thornless) Tree may reach 20m high and often has a single trunk. It may also branch near the base. The smaller branches are spreading and tend to droop. The light to dark grey Bark is thick and smoothish. It tends to flake with age.

Leaves

This deciduous tree has sparsely present Leaves that are bipinnate (compound: twice pinnate. The rachis or central axis has lateral “branches” – pinna – not leaflets and the leaflets are on these “side branches”). The leaves are on short side branches and have up to 7 pairs of Pinnae on which there are up to 14 pairs of closely ranked Leaflets. These leaflets are up to 9 x 4mm and are tightly packed. They may have a gland at the base of some leaflet pairs. The terminal pair are obovate (the reverse of ovate) and the rest are oblong. Lateral veins are visible below. The Margins may be rolled under and are entire (with a continuous margin, not in any way indented). The hairy Petiole (leaf stalk) is up to 2cm long. Stipules (basal appendages of the petiole) are not spinescent and usually shed early.

Flowers

The white, cream or yellow Flowers are in half spherical heads and have buds that are creamy-white and hairy. The flowers may appear before or with the new leaves. They are situated on a Pedicel (flower stalk) which is up to 5,5cm long. The base of the 5 lobed Calyx is a tube. The Corolla has a funnel shaped base ending with 5 lobes. Flower colour is due to the large number of long thin Stamens that are up to 1,5cm long. They are exserted and radiate well beyond the perianth (the 2 floral envelopes considered together; a collective term for the calyx and corolla) in a semi-spherical shape. The Anthers are peltate (shield shaped) with theca (pollen sacs) opening outwards. The superior Ovary is sessile or nearly so and contains several ovules. The filiform (thread or filament like) Style extends beyond the stamens. (Oct-Dec).

Fruit

The reddish brown, nearly flat Fruit is a Pod that has a distinctly oblong shape. It is up to 18 x 5cm and pods may appear in remarkable numbers. These pods may hang from the tree for several months. Individual pods may have visible darker transverse ridges. (Feb-Aug).

Distribution & Ecology

This Tree is located in Northern KwaZulu-Natal, Mpumalanga and Limpopo. It also occurs in Swaziland, Mozambique, Zimbabwe and Tanzania. It grows best in sandy soil, along riverbanks and is less common in rocky areas. Trees also occur in the arid bushveld (is a sub-tropical woodland ecoregion of southern Africa). Frequent Visitors during flowering season include Lilac-breasted roller, Glossy starlings, Fork-tailed drongos and Bee-eaters. Elephant and other game consume Leaves.

Ethnobotany

The Wood is used for building and carving.

References

Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.

Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.

Ginn, P.J. McIlleron, W.G. Milstein, S. 1989. The Complete Book of Southern African Birds. Struik Publishers (PTY) LTD. Third impression 1991.

Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965.

Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town.

Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.

Ginn, P.J. McIlleron, W.G. Milstein, S. 1989. The Complete Book of Southern African Birds. Struik Publishers (PTY) LTD. Third impression 1991.

 

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