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Hildegardia erythrosiphon (Baill.) Kosterm.

Protologue
Bull. Jard. Bot. Etat 24(4): 338 (1954).
Family
Sterculiaceae (APG: Malvaceae)
Vernacular names
Vinoa, vonoa (Fr).
Origin and geographic distribution
Hildegardia erythrosiphon is native to western Madagascar, where it occurs scattered over a large area.
Uses
The wood of Hildegardia erythrosiphon is sometimes used in traditional boat building. It could be useful for heat and sound insulation, for scale modelling and as core for slatted panels.
Properties
The heartwood of Hildegardia erythrosiphon is whitish and not distinct from the 3–4 cm wide sapwood. The grain is straight, texture coarse. The wood is soft and very light, with a density of 170–340 kg/m³ at 12% moisture content. The wood dries rapidly, with slight risk of distortion; shrinkage rates are low. The wood is stable when dried and easy to saw. It is not durable, but easy to treat with preservatives.
Botany
Small to medium-sized tree up to 20 m tall; bole up to 150 cm in diameter, swollen; outer bark rather smooth, blackish or greyish, more or less striate, inner bark 2–3 cm thick, fibrous; crown globose; branches cylindrical, short, horizontal. Leaves alternate, simple, entire or 3– 5-lobed; petiole up to 25 cm long, glabrous; blade orbicular in outline, 5–26 cm × 4.5–25 cm, base cordate, apex obtuse to acuminate, margin revolute, lower surface densely covered with whitish stellate hairs, upper surface glabrous, basal veins 7–9. Inflorescence a raceme grouped in pseudo-umbels at the end of leafless branches. Flowers bisexual or male, regular; pedicel glabrous, jointed; calyx persistent, red, 5-lobed with 5–8 mm long lobes; petals absent; stamens 10–20 on top of a long, slender androgynophore, anthers sessile; ovary superior, consisting of 5 free carpels on top of androgynophore. Fruit consisting of 1–5 samaras inserted on the top of the androgynophore; samaras 5–11 cm × 1.5–4 cm, stiped, with a large, veined membranous wing, 1-seeded.
Hildegardia erythrosiphon flowers before the leaves appear.
Hildegardia comprises 11 species, 3 each from mainland Africa and Madagascar, and 1 each from India, Indonesia, the Philippines, Australia and Cuba. Hildegardia erythrosiphon is variable and has been subdivided into several subspecies and varieties.
Ecology
Hildegardia erythrosiphon occurs in dry forest and thickets up to 600 m altitude, on calcareous, gneissic or sandy soils.
Genetic resources and breeding
Although the distribution area of Hildegardia erythrosiphon in Madagascar is rather large, it may be endangered by overgrazing and habitat destruction. It is not, however, included in the IUCN Red list of threatened species.
Prospects
The properties of the wood of Hildegardia erythrosiphon (low weight, softness, low durability) limit its usefulness to very specific uses. It may be a good substitute for balsa wood (Ochroma pyramidale (Cav. ex Lam.) Urb.) especially for insulation purposes and modelling. With good promotion, demand for the wood may increase.
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.
• Guéneau, P., Bedel, J. & Thiel, J., 1970–1975. Bois et essences malgaches. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 150 pp.
Other references
• Cheek, M. & Leach, G., 1994. Plants in peril, 20: Hildegardia. Kew Magazine 11(2): 88–94.
• Kostermans, A.J.G.H., 1954. A note on some African Sterculiaceae. Bulletin du Jardin Botanique de l’Etat (Bruxelles) 4: 335–338.
• Kostermans, A.J.G.H., 1960. Miscellaneous botanical notes 1. Reinwardtia 5(3): 233–254.
• Parant, B., Chichignoud, M. & Rakotovao, G., 1985. Présentation graphique des caractères des principaux bois tropicaux. Tome 5. Bois de Madagascar. CIRAD, Montpellier, France. 161 pp.
• Schatz, G.E., 2001. Generic tree flora of Madagascar. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 477 pp.
Author(s)
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
J.R. Cobbinah
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article:
Brink, M., 2007. Hildegardia erythrosiphon (Baill.) Kosterm. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.