Dombeya burgessiae (PROTA)

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Dombeya burgessiae Gerrard ex Harv.


Protologue: Fl. Cap. 2: 590 (1862).
Family: Sterculiaceae (APG: Malvaceae)
Chromosome number: 2n = 54

Synonyms

  • Dombeya mastersii Hook.f. (1867),
  • Dombeya platypoda K.Schum. (1900),
  • Dombeya dawei Sprague (1906).

Vernacular names

  • Pink dombeya, pink wild pear (En).

Origin and geographic distribution

Dombeya burgessiae is distributed from DR Congo, Uganda and Kenya south to Angola, Zambia, Zimbabwe and Mozambique and also occurs in South Africa and Swaziland.

Uses

The bark fibre of Dombeya burgessiae is widely used for binding and for making rope. In Kenya the fibre is traditionally used for making baskets and the famous ‘kiondo’ bags.

In Kenya the wood is used for construction and for making bows. In Mozambique the wood is used for bows, tool handles and for firewood. The wood is widely used to light a fire by friction. In Malawi and Mozambique the pith is boiled and eaten as a side dish. Like other species of the genus, Dombeya burgessiae is valuable as bee forage and the honey produced is exceptionally good with fine crystallization. Dombeya burgessiae is cultivated as an ornamental in southern Africa.

In traditional medicine in Kenya the bark is boiled and the decoction drunk or the bark is chewed as an aphrodisiac. An infusion of the roots is taken to cure stomach pain. In Tanzania a decoction of the leaves is drunk and pulped leaves are applied to leprosy sores.

Properties

The heartwood is not clearly demarcated from the sapwood. The wood is uniformly pale brown, often with a central core of dark brown wood with olive streaks. The grain is usually straight, texture fine to medium. The density of the wood is about 560 kg/m³ at 12% moisture content. The wood is liable to checking in seasoning. It is strong and tough. At 12% moisture content, the modulus of rupture is about 96 N/mm², modulus of elasticity 12,500 N/mm², compression parallel to grain 48 N/mm², shear 11.6 N/mm², cleavage 46 N/mm radial and 66 N/mm tangential, Janka side hardness 4140 N and Janka end hardness 5420 N.

The wood saws and planes well and nails without splitting, but it is not suitable for turnery. The durability of the wood is low to moderate. The sapwood is susceptible to attack by termites, marine borers and Lyctus borers. The sapwood and heartwood are moderately resistant to impregnation.

The leaves contain polyuronoids and steroids, and bufadienolides are probably also present in the leaf material. Water and methanol extracts of the leaves have no or negligible anti-bacterial activity. Ethanol and dichloromethane extracts of the leaves showed a high level of cyclooxygenase-1 (COX-1) inhibition, indicating anti-inflammatory activity. The treatment of wounds and stomach-ache may be attributable to these properties.

Botany

Shrub 2–4(–8) m tall; outer bark brown, inner bark tough and fibrous; branches densely hairy or glabrescent, with simple and stellate needle-shaped hairs, and subsessile and stalked glandular hairs. Leaves alternate, simple; stipules lanceolate to broadly ovate, 8–13 mm × 3–6 mm, long-acuminate; petiole 7–15 cm long; blade suborbicular, distinctly 3-lobed, rarely 5-lobed or entire, 11–23 cm × 7–18 cm, base deeply cordate, apex acuminate, margin irregularly toothed, upper surface sparsely to densely pubescent, tomentose or tomentellous, lower surface usually densely pubescent, tomentose or tomentellous, with mostly long-armed hairs. Inflorescence axillary, corymbose or subumbellate, 6–21 cm × 3–6 mm, many-flowered; peduncle 4–17 cm long, sparsely or densely hairy; bracts ovate, c. 11 mm long, acuminate, caducous. Flowers bisexual, regular, 5-merous; pedicel 22–40 mm long; epicalyx bracts at base of calyx, rarely on pedicel, elliptical, ovate, oblong, lanceolate or oblanceolate, 10–14 mm × 2–5 mm, acute to long-acuminate, caducous; calyx lobes reflexed, lanceolate, 9–13 mm × 2–8 mm, hairy outside; petals spreading, obliquely obovate, 12–25 mm × 10–25 mm, white or pink, base and veins sometimes red; stamens (10–)15, in groups of 3, alternating with staminodes 7–16 mm long, all filaments united into a staminal tube 1–5 mm long; ovary superior, globose, hairy, 5-celled, style 5–16 mm long, 5-branched. Fruit an ovoid to globose capsule 5–15 mm in diameter, brown, hairy. Seeds trigonous, 3–4 mm × 2 mm, rough, dark brown to black.

Dombeya burgessiae exhibits a lot of variation and was consequently described repeatedly under different names. In southern Africa Dombeya burgessiae flowers in April–July and fruits ripen in June–October.

Dombeya comprises about 200 species, mainly distributed in Madagascar, with about 20 species in mainland Africa and 14 in the Mascarenes. Revisions of the genus have been carried out for mainland Africa and the Mascarenes, but not for Madagascar, and the number of species described for Madagascar is possibly too high.

Ecology

Dombeya burgessiae belongs to the Afromontane flora and is found up to 2400 m altitude. In East Africa the lower altitude limit is c. 900 m, but in Mozambique and South Africa it can be found at sea-level. It is most common in the early stages of forest regrowth, in dry open forest, at forest margins, along rivers and in woodland.

Management

Seed can be extracted from dry flower heads. Its viability declines within 3 months, so fresh seed has to be used for sowing. Seed is to be sown in properly drained seedbeds. Seedlings emerge in about 3 weeks. For the ornamental trade, plants are multiplied by cuttings or air-layers.

Genetic resources

As Dombeya burgessiae is very widespread and common, it seems not threatened with genetic erosion. Germplasm of several species with ornamental value is available at various research institutes in the subtropics. Self-incompatibility is common in the genus and explains the wide variation in several species. It opens opportunities for selection and breeding. The first ornamental Dombeya hybrid is Dombeya ×cayeuxii André, produced in 1895 in Portugal as a result of crossing Dombeya burgessiae and Dombeya wallichii (Lindl.) K.Schum. from Madagascar. A number of named cultivars, selections from Dombeya burgessiae and hybrids with Dombeya burgessiae as one of the parents, have been developed in Florida (United States) and are planted as ornamentals elsewhere as well. The cultivar ‘Seminole’ has some promise as an indoor pot plant.

Prospects

As a fibre producer, Dombeya burgessiae will only remain important for local use. It contains bufadienolides which are of interest as potential anti-cancer agents. It is probable that the horticultural industry in the subtropics will continue to release new cultivars.

Major references

  • Cheek, M. & Dorr, L., 2007. Sterculiaceae. In: Beentje, H.J. & Ghazanfar, S.A. (Editors). Flora of Tropical East Africa. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 134 pp.
  • Latham, P., 2007. Plants visited by bees and other useful plants of Umalila, southern Tanzania. Third edition. P.Latham, DFID, United Kingdom. 216 pp.
  • Seyani, J.H., 1991. The genus Dombeya (Sterculiaceae) in continental Africa. Opera Botanica Belgica 2. National Botanic Garden of Belgium, Meise, Belgium. 186 pp.
  • Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.

Other references

  • Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
  • Coates Palgrave, K., 1983. Trees of southern Africa. 2nd Edition. Struik Publishers, Cape Town, South Africa. 959 pp.
  • Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
  • Reid, K.A., Jäger, A.K., Light, M.E., Mulholland, D.A. & van Staden, J., 2005. Phytochemical and pharmacological screening of Sterculiaceae species and isolation of antibacterial compounds. Journal of Ethnopharmacology 97(2): 285–291.
  • Soderholm, P.K., 1973. Dombeya ‘Seminole’ and D. ‘Pinwheel’, new cultivars for landscaping in the subtropics. Proceedings of the Florida State Horticultural Society 1973: 452–453.
  • Staples, G.W. & Herbst, D.R., 2005. A tropical garden flora: plants cultivated in the Hawaiian Islands and other tropical places. Bishop Museum Press, Honolulu, United States. 908 pp.
  • Stefanesco, E. & Bintoni-Juliassi, O., 1982. 101 wild fodder and food plants of Angonia province of Tete Mozambique. Field Document No 39. Ministry of Agriculture, Food and Agriculture Organization of the United Nations, Maputo, Mozambique. 208 pp.
  • van Wyk, B. & van Wyk, P., 1997. Field guide to trees of southern Africa. Struik Publishers, Cape Town, South Africa. 536 pp.
  • Williamson, J., 1955. Useful plants of Nyasaland. The Government Printer, Zomba, Nyasaland. 168 pp.

Author(s)

  • C.H. Bosch, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Bosch, C.H., 2011. Dombeya burgessiae Gerrard ex Harv. [Internet] Record from PROTA4U. Brink, M. & Achigan-Dako, E.G. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 2 March 2020.