Acacia rovumae (PROTA)

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Plant Resources of Tropical Africa
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Acacia rovumae Oliv.


Protologue: Fl. trop. Afr. 2: 353 (1871).
Family: Mimosaceae (Leguminosae - Mimosoideae)

Vernacular names

  • Mgunga (Sw).

Origin and geographic distribution

Acacia rovumae occurs in coastal regions of southern Somalia, Kenya and Tanzania, possibly also northern Mozambique, and in southern and western Madagascar.

Uses

In Tanzania the wood is used for house building and pestles, as firewood and for the production of charcoal. In Madagascar it is used for making furniture. Twigs are given as fodder to livestock in Madagascar.

Properties

The heartwood is reddish brown and nicely marked, moderately heavy and hard. It is resistant to termite attack.

Description

  • Small to medium-sized tree up to 20(–30) m tall; bole up to 130 cm in diameter; bark rough or smooth, grey-green to dark grey or dark brown, often with thick, woody prickles; crown open, flat; branchlets shortly hairy, with pairs of straight or only slightly curved, blackish prickles 4–8 mm long just below the nodes.
  • Leaves alternate, bipinnately compound, with (3–) 4–9 pairs of pinnae; stipules small, caducous; petiole (1–)2–4 cm long, with 1–2 glands, rachis 1.5–7 cm long, with glands between top pairs of pinnae; leaflets in (5–)8–31 pairs per pinna, obliquely oblong, 4–9(–12) mm × 1.5–4 mm, shortly hairy especially beneath, bluish green.
  • Inflorescence an axillary spike 6–10 cm long; peduncle 1–3.5 cm long.
  • Flowers bisexual, regular, 5-merous, small, creamy white but with reddish calyx, fragrant, almost sessile; calyx cup-shaped, 1.5–2 mm long, hairy; corolla 2–3 mm long, with short lobes; stamens numerous, free, 4–6 mm long; ovary superior, shortly stalked, style slender, up to 5 mm long.
  • Fruit an oblong pod 5–15 cm × 1.5–3 cm, flat, straight, woody, nearly glabrous, dark brown, indehiscent, c. 9-seeded.
  • Seeds oblong to disk-shaped, 8–13 mm × 7–9 mm.

Other botanical information

Acacia is a large pantropical genus, comprising more than 1300 species; most of them are found in Australia (more than 900), more than 200 in America, and about 130 in Africa. Acacia rovumae belongs to subgenus Aculeiferum, which accommodates all African Acacia species with non-spinescent stipules and hooked prickles. Acacia rovumae resembles Acacia burkei Benth., which has more strongly hooked prickles, less numerous leaflets and narrower, dehiscent pods.

Acacia rovumae flowers when new leaves develop. The indehiscent pods are possibly dispersed by water.

Ecology

Acacia rovumae occurs in riverine forest and swamp forest near the coast, often at the inner margin of mangroves, in Madagascar also in deciduous woodland and scrubland on calcareous soils, usually at lower altitudes but in East Africa occasionally up to 700 m altitude.

Management

The trees coppice readily and can be managed for the production of branches used as fodder.

Genetic resources

Although Acacia rovumae is not very widespread, there are no indications that it is threatened by genetic erosion.

Prospects

Too little is known about Acacia rovumae to evaluate its prospects as a timber tree of wider use. With its rather specific habitat requirements, it seems unlikely that it will gain importance.

Major references

  • Brenan, J.P.M., 1959. Leguminosae subfamily Mimosoideae. In: Hubbard, C.E. & Milne-Redhead, E. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 173 pp.
  • du Puy, D.J., Labat, J.N., Rabevohitra, R., Villiers, J.-F., Bosser, J. & Moat, J., 2002. The Leguminosae of Madagascar. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 750 pp.
  • Ratsinarson, J, Randrianarisoa, J., Ellis, E., Jean Emady, R., Efitrioarany, Ranaivonasy, J., Razanajaonarivelona, E.H. & Richard, A.F., 2000. Beza Mahafaly: écologie et réalités socio économiques: la flore de Beza Mahafaly. Recherches pour le développement, Série Sciences Biologiques 18: 14–24.

Other references

  • Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
  • Brenan, J.P.M., 1970. Leguminosae (Mimosoideae). In: Brenan, J.P.M. (Editor). Flora Zambesiaca. Volume 3, part 1. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 153 pp.
  • Kemp, P.B., 1951. The susceptibility of wood to termite attack. East African Agricultural Journal 16(3): 122–123.

Author(s)

  • R.H.M.J. Lemmens, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Lemmens, R.H.M.J., 2006. Acacia rovumae Oliv. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 28 November 2017.