Prota 7(2): Timbers/Bois d’œuvre 2
Kew Bull. 50(3): 581 (1995).
Caesalpiniaceae (Leguminosae - Caesalpinioideae)
Cassia lactea Vatke (1880).
Origin and geographic distribution
Senna lactea is endemic to northern Madagascar, south to Mananara.
The wood is used for furniture, and also as firewood and for charcoal production. Senna lactea is planted as a shade tree in coffee plantations.
The wood is reportedly yellowish and strong.
Deciduous small to medium-sized tree up to 30 m tall; bole up to 150 cm in diameter; bark surface grey, often mottled; twigs short-hairy. Leaves alternate, paripinnately compound with (11–)15–22(–25) pairs of leaflets; stipules awl-shaped, 5–7 mm long, early caducous; petiole 2.5–4 cm long, rachis up to 30 cm long, grooved; petiolules 2–3 mm long; leaflets opposite to alternate, oblong, 2–5.5 cm × 0.5–1.5 cm, rounded to notched at apex, glabrous or sparsely hairy, pinnately veined. Inflorescence a terminal or axillary raceme 5–12 cm long, often combined into a lax panicle at ends of shoots, short-hairy. Flowers bisexual, slightly zygomorphic, 5-merous; pedicel 12–18 mm long; sepals free, unequal, 3–8 mm long, reflexed, tinged red; petals free, nearly equal, oblong-elliptical, 10–11 mm long, white, sometimes tinged pink; stamens 10 of which 7 fertile and up to 9 mm long, 3 rudimentary and up 5 mm long; ovary superior, 6–7 mm long, style 5–6 mm long, curved. Fruit a strap-shaped, flat pod 16–20 cm × 3–4 cm, with transverse lines between the seeds, glabrous, reddish brown to blackish, dehiscing with 2 thin valves remaining fused at one margin, up to 22-seeded. Seeds oblong, flat, c. 1 cm × 0.5 cm, smooth, brown.
Senna lactea can be found flowering from April to August.
Until the early 1980s, Cassia was considered a very large genus of about 550 species, but was then split into 3 genera: Cassia s.s. with about 30 species, Chamaecrista with about 250 species and Senna with about 270 species. Senna is very similar to Cassia, but is distinguished from it by the possession of 3 adaxial stamens which are short and straight, and the pedicels which have no bracteoles.
Madagascar has 9 endemic Senna species. Additional to Senna lactea, some of these have documented uses of their wood. Senna meridionalis (R.Vig.) Du Puy is a shrub or small tree up to 5 m tall restricted to south-western Madagascar. The branches are used as poles in building local houses. Senna viguierella (Ghesq.) Du Puy is a shrub or small tree up to 8 m tall occurring in southern Madagascar. Its wood is also used in house construction.
Senna siamea (Lam.) H.S.Irwin & Barneby, a small to medium-sized tree up to 20 m tall originating from tropical Asia, is planted in western Madagascar and also in mainland tropical Africa. Although it is most commonly used for firewood and as ornamental, it is sometimes also planted for poles because of its durable wood.
Senna lactea occurs in humid evergreen forest from sea-level up to 1600 m altitude, often along rivers, but it can also be found in degraded vegetation.
Genetic resources and breeding
Although Senna lactea has a comparatively small area of distribution, it has not been reported to be endangered. It has been recorded as locally common as an adventive in degraded vegetation and thus may survive in areas subject to forest degradation caused by human intervention.
Too little is known about Senna lactea to judge its prospects as a timber tree of more commercial importance. It may have possibilities as an auxiliary plant and may be interesting for planting in agroforestry systems. However, much research is still needed, e.g. on wood properties, growth rates and propagation.
• 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.
• Capuron, R., 1968. Contributions à l’étude de la flore forestière de Madagascar. A. – Notes sur quelques Cassiées malgaches (1re partie). Adansonia, series 2, 8(1): 17–37.
Correct citation of this article:
Lemmens, R.H.M.J., 2010. Senna lactea (Vatke) Du Puy. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.