Indigenous trees of Southern Africa (Part 3) – Cape Ash
By Gareth Coombs
Cape Ash (Ekebergia capensis) is a large semi-deciduous tree that naturally occurs along the entire coast from Cape Town and surrounds, eastward to Mozambique, and into areas along the north and South East of Zimbabwe. It has a disjunct distribution, and is also found in Northern Botswana. Owing to its lush canopy and attractive branching pattern it makes an excellent garden and street tree. Large trees can reach up to 30 metres in height but are usually smaller, ranging from 7-15 metres. Mature trees can have different branching patterns but the branching is usually upright and spreading widening from the base to the top of the canopy. The growth form can be different depending on its environment. It can also spread laterally and form a rounded, lush green canopy that makes and excellent shade tree for gardens and public spaces.
No discussion on the Cape Ash or Cape plum is complete without that of distinguishing between the appearance of the two. Due to the similarities of Cape Ash and Wild Plum, there has always been some debate on how to readily distinguish these. The easiest distinguishing feature are the fruits which will allow you to instantly distinguish the round, berry shaped fruits of the Cape Ash from the much larger oblong, bright red coloured plums of the Wild plum. When these are not fruiting, the difference can be told apart by the leaves that are distinctively more sickle shaped in the Cape plum and straighter in the Cape Ash.
Collecting fruits and seeds
This species produces distinctive large berries, each usually containing 1- 4, kidney shaped seeds. The fruit color varies from a lightly streaked red and cream colour to a darker uniform crimson red. Green fruits are borne for 2-3 months on the tree before ripening when they are often distinctively seen on the tree and can form a dense litter on the ground where they drop. This is however seldom a nuisance to traffic or pedestrians. Fruiting trees are commonly found throughout cities, towns or gardens and the fruits can either be picked directly from the tree or picked up from the ground. Once fruits have been collected they can be stored for several days with the pulp still present, however, the pulp invariably begins to decay and attracts small fruit flies. It is therefore advisable to first remove the pulp from the seeds and store seeds after the fruit pulp has been cleaned off. Seeds can be washed with a diluted solution of household bleach (sodium hypochlorite) which inhibits fungal decay during storage. Despite the soft fleshed fruits, the seeds can be stored for at least one season, and will survive longer than this in optimal conditions.
Planting seeds and propagation
Seeds should be planted from late august to March and germinate well in mixture of 1-2:1 compost: field soil. Seeds can be sown in bags or seed trays at a depth of 3 cm. Once planted the soil must be kept moist, in a shaded area. Personal Nursery data indicates median germination period of around 47 days. Newly germinated seedlings bare two cotyledons that remain close to the soil and as the newly developing stem grows from these. This is different Cape plum where the cotyledons are kept closer to the leaf petals as the seedling stem develops. As the seedlings develop, the cotyledons shrink and become wrinkled as seedling ages. Seeds can be stored dry for some time, but there is some reduction in their viability. When the growth tip is removed, new meristems sprout from the base of the cotyledons, same in some other species.
Germinated seedling can be pricked out from planting trays very carefully and transplanted at any time from 3-5 days after germinating, however very young seedlings can be prone to damping off fungi and allowing seedlings to reach larger sizes before transplanting is advisable.
Seedling care and planting out
Seedlings can be grown for several months within the original planting container and do not compete aggressively. Once seedlings reach about 25cm they are ready for transplanting. Larger seedlings will usually transplant better and are less susceptible to fungal infection. Seedlings are not very drought tolerant and need to be watered regularly, as water stress is often followed by the development of wilting diseases in this (and other) tree species. Plants should be kept in shaded or at least partial shade for the first year until they are large enough to harden off and plant in full sun. This is a relatively fast growing species and can reach over 1m in 3 years when grown from seed. Growth rate of seedlings is variable and up to appr. 30 cm per year for the first two years, but this could be faster under optimal irrigation and fertilizing schedules.
Natural history notes
Cape ash is a valuable fruit tree that provides both habitat and a food source for birds and mammals. including baboon, vervet monkey, bushbuck, nyala, red winged starlings, Knysna turaco, black collared barbets and crowned hornbills.
Selected references and further reading
Dlamini, M.D. 2004. Ekebergia capensis Sparmm. SANBI. Available online at: http://pza.sanbi.org/ekebergia-capensis
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of southern Africa, 3rd Ed. Struik, Cape Town.
*Related article: Indigenous Trees of Southern Africa (Part Two) – Cape Plum