Marula (Sclerocarya birrea (A. Rich.) Hochst.) is a multipurpose deciduous African tree that produces prized juicy fruits, seeds rich in oil and protein. Marula is well known for its multiple potential uses, including animal feeding, and it could be valuable in agroforestry systems. However, as of 2021, the tree is not widely cultivated and remains underutilized.
Description
Marula is a deciduous, dioecious tree that can reach 9-12 m (occasionnally 18 m) in height. It has a rounded spreading leafy crown, a short bole (up to 4 m tall x 1.2 m in diameter) and a cracked grey bark. The tree is deeply (down to 30 m ) taprooted. The leaves are borne in clusters at the apex of stout branchlets. They are alternate, 8-38 cm long imparipinnate, bearing 3-18 pairs of leaflets. Lateral leaflets subsessile, terminal leaflet petiolated. The limb is glabrous, round to oblong-elliptical or elliptical, dentate-serrate in shape, 1–9 cm long × 0.5–3.5 cm broad. The male inflorescences rare terminal or axillary, drooping raceme 5–22 cm long, with flowers in groups of 3–4 towards the base but solitary towards the apex. The female inflorescences are reduced, subterminal and spiciform, with 1–2(–3) flowers. The flowers are small, shortly pedicellate, whitish purple to red in colour. The fruits are obovoid fleshy and juicy drupes, 2-3.5 cm in diameter, green becoming yellow at maturity. The flesh surrounds a hard stone, 2.5–3 cm long × 1.5–2.5 cm wide, that contains 2 oily seeds (POWO, 2021; Hall, 2002).
Uses
Marula is mainly used for its edible and prized fruits in Africa, which are consumed in different forms by local populations, for example in South Africa, Namibia, Niger, and Burkina Faso (Shackleton et al., 2002; Hiwilepo-van Hal, 2013). The fruit, eaten fresh without its thick skin, has a delicate nutty flavour and contains a higher concentration of vitamin C than oranges. The juice is drank fresh or it can be boiled to flavour and sweeten porridge. The fruit can be fermented to prepare an alcoholic beverage called "marula beer" (maroela mampoer or amarula), which can be consumed directly or further distilled into stronger alcohol. The pit is high in protein, and the oilseed contains antioxidants. The kernels are eaten as snack, or crushed and used to make cakes or biscuits or as a soup or dish ingredient (mixed with wild spinach and served with maize meal). The oil extracted from the seed is used as cooking oil, for meat preservation, or for skin care. In Benin, marula leaves are known to stimulate milk production in nursing women (Gouwakinnou et al., 2011). In South Africa leaves are cooked as relish by local population (Shackleton et al., 2002).
Several marula products are used to feed livestock.
- Leaves are used to feed cattle, sheep, goats or pigs. Though not a common browse, the tree is used in times of drought (Gouwakinnou et al., 2011; Mlambo et al., 2011a; Thiong’o et al., 2002; Shackleton et al., 2002).
- Fruits are used to feed sheep, goats, pigs, and wild animals (Shackleton et al., 2002; Gouwakinnou et al., 2011).
- The oil seed cakes that are commercially available are usually obtained after cold pressure and contain 35-45% of residual oil (Mlambo et al., 2011b; Mthiyane et al., 2017; Phenya, 2018). This type of meal is used in beef cattle or goat feeding, (Mlambo et al., 2011) dairy cows feeding (Mdziniso et al., 2016; Malebana et al., 2018), and Japanese quail feeding (Mazizi et al., 2019).
Marula provides shade to livestock and to underneath forage grasses. Marula wood is used for furniture, carving, utensils, and as a good firewood. The inner bark yields fibre for ropes and a red-brown dye used in traditional crafts. Marula flowers produce attractive nectar for pollinators. Bark and fruits have several ethnomedicinal uses. For cattle, an infusion of the fruit is used as a tick killer.
Though it is not commonly cultivated, marula is reported to be easy to propagate and could be valuable in agroforestry systems (POWO, 2021; Gouwakinnou et al., 2011; Shackleton et al., 2005; Hall, 2002).
