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Dombeya rotunda Arènes

Protologue
Candollea 16: 310 (1958).
Family
Sterculiaceae (APG: Malvaceae)
Origin and geographic distribution
Dombeya rotunda is endemic to Madagascar, where it occurs in the western and central parts of the country.
Uses
The bark fibre is used for cordage. The bark was formerly made into barkcloth. The wood is made into articles such as hollow cylinders for bellows in smithies, measuring tools for rice, and drums.
Properties
The wood is white, lightweight and soft, and it works well.
Botany
Tree with young branches ferruginous-hairy, older branches with a greyish bark and small, brown stellate hairs. Leaves alternate, simple; stipules ovate, 12–15 mm × 4 mm, long-acuminate, ferruginous-hairy, caducous; petiole up to 10 cm long, cylindrical, ferruginous-hairy; blade suborbicular, up to 16 cm × 16 cm, base deeply cordate, apex 1–3-cuspidate, margin coarsely and irregularly toothed, both surfaces covered with glandular stellate hairs, but lower surface more densely than upper one, palmately veined with 9 basal veins, venation prominent below. Inflorescence an axillary umbel, with ferruginous stellate hairs, 2–7-flowered; axis simple or bifurcated; bracts ovate, c. 6 mm long, acuminate, stellate-hairy, persistent. Flowers bisexual, regular, 5-merous; pedicel 10–20 mm long; epicalyx bracts 3, ovate, 15 mm × 4 mm, long-acuminate, persistent; calyx deeply 5-fid, lobes triangular, c. 20 mm × 4 mm, apex acuminate, densely glandular outside, ultimately reflexed; petals free, obovate-suborbicular, 20–22 mm × 15–18 mm, papillose; androecium tube-shaped, staminal tube 5–6 mm long, stamens 15, filaments unequal, 1–4 mm long, alternating by 3 with 5 staminodes 10–12 mm long; ovary superior, hairy, stylar column 14–15 mm long, with 5 branches 2.5–5.5 mm long. Fruit a subglobular capsule 10–12 mm long, papillose, stellate-hairy, loculicidal. Seeds ovoid, 3 mm × 2 mm, obliquely truncate, brown, shiny.
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 hav 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.
Various other Dombeya species endemic to Madagascar are used as fibre plants. The bark fibre of Dombeya perrieri Arènes, a tree, can be used for cordage or rough sacks. The fibre of Dombeya pubescens (Hochr.) Arènes, a shrub or small to medium-sized tree up to 25 m tall, is used much in the same way as that ofDombeya rotunda. The bark of Dombeya selinala Arènes, a shrub or small tree up to 8 m tall, provides good cordage fibre.
Ecology
Dombeya rotunda occurs up to c. 800 m altitude, in forest, on rocks and along rivers.
Management
Formerly the bark was beaten with a mallet to obtain barkcloth, later the fibre was extracted by crushing the bark, after which the fibre was combed or scutched, making it suitable for spinning and weaving.
Genetic resources and breeding
It is unknown whether Dombeya rotunda is threatened by genetic erosion.
Prospects
The bark fibre of Dombeya rotunda is locally used for making cordage, and the wood is used for small articles. The absence of detailed information on the extent of its use and the properties of its fibre and wood makes assessment of the prospects of this species difficult.
Major references
• Arènes, J., 1959. Sterculiacées (Sterculiaceae). Flore de Madagascar et des Comores (plantes vasculaires), famille 131. Firmin-Didot et cie., Paris, France. 537 pp.
• Boiteau, P., Boiteau, M. & Allorge-Boiteau, L., 1999. Dictionnaire des noms malgaches de végétaux. 4 Volumes + Index des noms scientifiques avec leurs équivalents malgaches. Editions Alzieu, Grenoble, France.
Other references
• Decary, R., 1946. Plantes et animaux utiles de Madagascar. Annales du Musée Colonial de Marseille, 54e année, 6e série, 4e volume, 1er et dernier fascicule. 234 pp.
• Missouri Botanical Garden, undated. VAST (VAScular Tropicos) nomenclatural database. [Internet] http://mobot.mobot.org/ W3T/Search/ vast.html. Accessed February 2010.
• Schatz, G., undated. A catalogue of the vascular plants of Madagascar. [Internet]. Missouri Botanical Garden, St. Louis, United States. http://www.efloras.org/ flora_info.aspx?flora_id=12. Accessed September 2009.
• Seyani, J.H., 1991. The genus Dombeya (Sterculiaceae) in continental Africa. Opera Botanica Belgica 2. National Botanic Garden of Belgium, Meise, Belgium. 186 pp.
Author(s)
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
E.G. Achigan Dako
PROTA Network Office Africa, World Agroforestry Centre (ICRAF), P.O. Box 30677-00100, Nairobi, Kenya

Correct citation of this article:
Brink, M., 2010. Dombeya rotunda Arènes. In: Brink, M. & Achigan-Dako, E.G. (Editors). Prota 16: Fibres/Plantes à fibres. [CD-Rom]. PROTA, Wageningen, Netherlands.