Prota 7(1): Timbers/Bois d’œuvre 1
Mildbr., Wiss. Erg. deut. Zentr.-Afr. Exped., Bot. 5: 506 (1912).
Sterculiaceae (APG: Malvaceae)
Mubende witch tree (En). Mshunduzi (Sw).
Origin and geographic distribution
Pterygota mildbraedii occurs in eastern DR Congo, Rwanda, Burundi, Uganda, Tanzania and possibly Zambia. Additionally, a few collections have been recorded from the border area of Nigeria and Cameroon.
In Uganda the wood of Pterygota mildbraedii is used for beer vessels. It is also used as fuel and to make charcoal. The tree is planted as ornamental avenue tree and for shade.
Production and international trade
The wood is traded on local markets, e.g. in Uganda.
No specific information on the wood properties is available, but Pterygota wood is generally medium-weight, moderately hard, and not durable, but can be easily treated with preservatives.
Deciduous, medium-sized to very large tree up to 60 m tall; bole branchless for considerable length, up to 200 cm in diameter, with stout buttresses up to 3 m high; bark surface grey, smooth, inner bark yellowish; crown open, with heavy, spreading branches; young branches densely stellate golden-brown hairy. Leaves alternate, simple; stipules soon falling; petiole 7–22 cm long; blade ovate in outline, up to 30 cm × 25 cm, shallowly 3–5-lobed, base cordate, apex short-acuminate, densely stellate hairy when young but glabrescent, with 5–7(–9) veins from the base and c. 4 pairs of lateral veins, with pockets of stellate hairs in vein axils. Inflorescence an axillary panicle 7–10 cm long, golden brown stellate hairy. Flowers usually unisexual, regular; pedicel up to 4 mm long; calyx campanulate, 5-lobed, lobes oblong, 4–10 mm × 3–4 mm, densely golden brown stellate hairy outside; male flowers with 4–5 mm long staminal column, with up to 20 anthers at apex and surrounding 5 rudimentary carpels; female flowers with superior ovary consisting of 5 ovoid carpels fused at base, c. 6 mm × 3–4 mm, each carpel with slender, c. 4 mm long style and flat stigma. Fruit consisting of 1–5 oblong-ovoid follicles 12–13 cm × c. 9 cm, woody, with 1–1.5 cm long stipe, many-seeded. Seeds 7–10 cm long, including a wing of 5–6 cm long. Seedling with epigeal germination; hypocotyl c. 4 cm long, epicotyl c. 0.5 cm long; cotyledons ovate, leafy; first leaves alternate.
Pterygota mildbraedii is a fast-growing tree.
Pterygota is a pantropical genus comprising 15–20 species, of which about 10 occur in tropical Africa and the Indian Ocean islands. It is closely related to Sterculia.
Pterygota mildbraedii occurs in riverine and gallery forest and secondary forest in mountains. In north-western Katanga (DR Congo), where the mean average annual temperature is 24°C, with mean maxima of 30.5°C and mean minima of 17°C, with about 1500 mm annual rainfall and a dry season of 4 months, it is common in association with Klainedoxa gabonensis Pierre in climax vegetation on red alluvial soil, but is very rare on base-rich volcanic soils. Its presence in Uganda is scattered; it is locally common, but may be absent from nearby locations.
Seeds can be collected from the ground when the fruits have split open, but they are easily attacked by insects. They may also be collected from mature fruits. Seeds germinate readily and no seed treatment is needed. Wildlings may also be used for planting. Its fast growth and small crown makes Pterygota mildbraedii suitable for planting in mixed stands. Trees may be managed by pollarding and coppicing.
Genetic resources and breeding
Pterygota mildbraedii is widespread and its habitat is not significantly threatened.
Too little is known of the wood of Pterygota mildbraedii to assess its prospects. However, as all Pterygota wood seems similar it may become more important as a fast growing, general-purpose timber tree suitable for planting in mixed plantations.
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Correct citation of this article:
Oyen, L.P.A., 2008. Pterygota mildbraedii Engl. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.