African Wildlife & Environment Issue 83

GARDENING FOR BIODIVERSITY

Although there are about twenty indigenous species in the genus Grewia , the one most commonly grown, and probably most widely distributed, is the Cross-berry Raisin Grewia occidentalis . The genus is named after an English physician and botanical author, N. Grew, who lived at the turn of the 17th century. However, the species name occidentalis , which means ‘western’, appears to be something of a misnomer as the plant occurs naturally from the Cape Peninsula right up to and over our northern borders and virtually everywhere in the eastern part of the country, from almost sea level to an altitude of over 2 000 meters. There are records of specimens growing naturally in every province of the country excluding the Northern Cape.

A scrambling shrub, or occasionally a small tree, G. occidentalis is usually multi-stemmed making it useful as a screen plant, which can even be interspersed with other species to create a dense hedge. It can also be shaped to become neat and compact, and is not a problem near buildings as its roots are not invasive. If trimmed to be kept low, it can be used as an excellent bank cover. While popular with some bonsai enthusiasts, for this purpose it has to be pruned back after flowering to maintain the desired shape. Because of a strong desire to scramble, it is a good candidate for making a large alien garden tree somewhat more environmentally friendly by

From an aesthetic point of view in the garden, G. occidentalis has the advantage that its starry flowers are quite attractive. They are usually mauve, but can vary from pink to white and have a cluster of golden-yellow stamens protruding from the centre. The unusual fruit, which resembles four balls joined together in the shape of a cross, is soft and sticky when fresh but becomes woody with age, turning purplish-brown. Its shape gives rise to the usual common name as well as to the alternative one of ‘Four Corners’. Not only birds seek out these edible fruits, as humans and monkeys also find them quite palatable.

just planting it nearby and letting it climb up. Once at the top of the tree, G. occidentalis will form its own spreading canopy. Of course this is only an option if the exotic tree is not classed as an invasive species, for in such a case it should obviously rather be removed so that it cannot spread elsewhere. Indeed, there is an invasive alien plant with a similar tendency to climb up trees, namely the nasty Barbados Gooseberry Pereskia aculeata . From South and Central A m e r i c a ,this is one of the most pernicious invaders in KwaZulu Natal, but has also reared its ugly head in other provinces such as Western Cape, Eastern Cape, Gauteng and Limpopo. It is a master of survival and any piece of stem, or even just a leaf, left in contact with the soil will grow again. Cut stems hanging in a tree can survive for years and simply re root and carry on growing when they fall down. At a glance P. aculeata looks like bougainvillea, but the leaves are more succulent and there are two short, curved spines on the

The pretty flower of Grewia occidentalis (Photograph C Botha)

32 | African Wildlife & Environment | Issue 83 (2023)