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

Tree

Khaya anthotheca, Khaya nyasica

RSA Tree No. n/a.

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.

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

Leaves

The Leaves are large – up to 30cm long, spirally arranged and paripinnate (compound leaf ending in a pair of leaflets). 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. 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 sweet scented Flowers are whitish, 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

Fruit is an ovate, erect, 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) and contains many flattened, narrowly winged Seeds. (Mar-Sep).

Distribution & Ecology

These trees are commonly found in evergreen forests at medium to low altitudes – up to 1 500m and 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. Glossy eggs from the female moth (Heteronygmia dissimilis) are laid 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 and 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 is grown 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