General Info

This large Tree has a much-branched crown. The paripinnate Leaves are red when young. The small, unisexual, actinomorphic Flowers are monoecious. Fruit is a capsule with winged Seeds.

Description

Khaya anthotheca, Khaya nyasica.

RSA Tree No. n/a. Zimb. No: 422.

Common names: Red or White mahogany, East African Mahogany, Nyasaland mahogany.

Family:  Meliaceae (Mahogany family). This family of shrubs and small trees has 50+ genera and 570+ species. In southern Africa, there are about 6 genera and 11 species including Ekebergia, Nymania, Khaya and Trichilia. Perhaps the best-known local alien tree in this family is the seringa (Melia azedarach). This tree is now considered invasive in the RSA. Most trees are evergreen and Leaves are large, simple or compound, lack stipules and are usually alternate. They occur in a large cluster or on short shoots. The bisexual or unisexual Flowers are regular, axillary and solitary. The Calyx has 4-5 sepals, which are free to near the base. The 4 Petals are imbricate (having regularly arranged, overlapping edges). The 5 to many Stamens are free except at the base and the Anthers are attached in the middle. The superior Ovary has a simple Style, which ends in a disc-like, head-like or lobed Stigma. The Fruit is a capsule or a drupe and may be winged or have a pulpy covering.

Name derivationKhaya.  Info attached to the tree in Kirstenbosch NBG includes “It is said that the first visiting botanist who saw the tree growing in in a forest somewhere in Africa asked the guide what the tree was called. The guide said “khaya” which in his language meant, “I don’t know”. The botanist, not knowing any better, diligently wrote down the name and the genus was named accordingly.”  anthotheca – Flower capsule. Not indigenous in the RSA.

Conservation Status: In the IUCN Red List, it is listed as Vulnerable.

Tree

This is a large, impressive Tree and may, in some cases, reach 60+m high. The trunk may be up to 4,5m and may become buttressed with age. The much-branched crown may be elongated or rounded. Branching occurs high up the trunk. New growth is red. The grey to brown Bark tends to flake.

Leaves

The spirally arranged and paripinnate (compound leaf ending in a pair of leaflets) Leaves are large – up to 30cm long. There are 2-7 pairs of entire (with a continuous margin, not in any way indented but may be hairy) Leaflets which are opposite or nearly so. Each hairless, oblong-elliptic leaflet is up to 17 x 7cm. The Blade is dark, glossy green above and much lighter below. Young leaves are pink (photo 785). Lateral veins are visible on both surfaces. The Margin is smooth and rolled under. The Apex may end abruptly with a pointed tip. The Base is asymmetric and broadly tapering to rounded. The Petiole (stalk of leaf) is up to 7cm long. Petiolules (leaflet stalks) are up to 1,5cm long. Stipules (basal appendages of the petiole) are absent. Young leaves are red.

Flowers

The whitish, sweet scented Flowers are actinomorphic (regular, symmetrical. Perianth, the calyx and corolla, are divisible into 3 or more identical sectors). Large numbers occur in Panicles (indeterminate, branched inflorescences with stalked flowers) near the ends of branches. The flowers are monoecious (having both male and female reproductive organs on the same plant) and unisexual. They are about 1cm in diameter. The male and female flowers are very similar. Each white flower is small up to 1cm wide and aromatic. Floral parts are in 4’s or 5’s. The Calyx is small and the sepals are joined close to the base and never completely cover the corolla in the bud. The Corolla contains free, erect, twisted Petals up to 6mm long. Male Flowers have joined Stamens forming a tube, which may reach 6mm in length. The staminal urn-shaped tube has a swollen middle and narrowing top. The Disc (a more or less fleshy or elevated development of the receptacle) in is cushion shaped in male flowers it. It is less conspicuous in Female Flowers. Here there is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) with a superior Ovary that has 4-5 locules – each with 12-18 ovules. There is a single short Style and the Stigma has a disc shaped head. (Sep-Dec).

Fruit

The ovate and erect Fruit is a woody Capsule (a dry fruit resulting from the maturing of a compound ovary – of more than one carpel – usually opening at maturity by one or more lines of dehiscence). It is up to 8cm in diameter and splits into 4-5 valves (the units or pieces into which the capsule splits, or divides in dehiscing). The fruit contains many flattened, narrowly winged Seeds. (Mar-Sep).

Distribution & Ecology

The ideal Location for these trees is in evergreen forests at medium to low altitudes – up to 1 500m, where the rainfall is in excess of 1 200mm per annum. They occur in Zimbabwe, Mozambique, Zambia, Tanzania, Malawi, Congo, DRC, Tanzania, Angola and northwards. The female moth (Heteronygmia dissimilis) lays glossy eggs on the bark. These develop into hairy larvae, which move to the leaves and can almost defoliate the tree. Hypsipyla grandella and H. robusta are borers that can also create major problems.

Ethnobotany

The Bark has a bitter taste. The Wood is hard, and the heartwood is borer and termite resistant. It is reddish with an attractive grain, takes a good polish and works easily. It is used for canoe, furniture making, for fuel and charcoal manufacture. The stem, bark and seeds contain Limonoids, which also cause the bitter taste in citrus fruit. The tree occurs in plantations in the RSA. The wood has a moderate density of about 620kg per cubic m. This deep shade tree grows up to 1m per year. It is easily grown from seed.

References

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

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.

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

 

http://www.digplanet.com/wiki/Heteronygmia_dissimilis

https://en.wikipedia.org/wiki/Khaya_anthotheca

http://www.plantzafrica.com/plantklm/khayaantho.htm

http://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=133440

https://www.ncbi.nlm.nih.gov/pubmed/16462017

http://www.prota4u.org/protav8.asp?p=Khaya+anthotheca

http://posa.sanbi.org/flora/browse.php?src=SP