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Carissa macrocarpa (Eckl.)A.DC. 1844
pronounced: kar-ISS-uh mack-roe-KAR-puh
(Apocynaceae – the oleander family)
common names: Natal Plum, Big Num-num, Grootnoem-noem, Amatungulu
Carissa is the Latinized form of the Indian vernacular name for this genus; macrocarpa is from the Greek, μακρος (makros), large and καρπος (karpos), fruit.
This is a fast-growing ornamental shrub that is wind-resistant and can grow in coastal areas. The fine healthy-looking plant photographed is growing only a few metres from the sea, in a Picnic Bay seafront garden. As the common names suggest, it is a native of South Africa, where it is grown commercially for its fruit. In its natural state, it is usually found on sand dunes and on the edges of coastal forests in Eastern Cape Province northwards from Natal to Mozambique. It is also naturalized in southern Florida, and is cultivated in southern California.
The plant usually forms a dense thorny shrub, but it can grow into a small tree anything up to 4 m in height. It has Y-shaped thorns. The young branches are green, and all parts of the plant exude a white, milky, non-toxic latex. The leathery leaves are a shiny dark green on the upper surface and paler below. They are about 2 – 6 cm long by 1.5 – 3.5 cm wide, ovate, oval or almost orbicular in shape. The tips of the leaves are sharply or bluntly pointed, and usually mucronate.
The flowers vary in size, up to 3.5 cm in diameter, have 5 white petals, and smell like orange blossom, the scent intensifying at night; the corolla tube is hairy within. The plant blooms for months at a time.
A traditional food plant in Africa, this little-known fruit has potential to improve nutrition, boost food security, foster rural development and support sustainable landcare. The large oval red fruit, about 5 cm long, is edible, and is rich in Vitamin C, calcium, magnesium and phosphorus. It tastes like a slightly sweet cranberry, with the texture of a ripe strawberry. It can be eaten straight from the plant, or made into pies, jams, jellies and even sauces. A ripe fruit is one that is plum red and slightly soft to the touch – no peeling is necessary. Halved and quartered and seeded, it is suitable for fruit salads and as topping for cakes.
The plant is easy to grow. Its seeds germinate between a fortnight and a month after sowing. The seedlings develop very slowly at first, but will bear fruit within the first 2 or 3 years. Vegetative reproduction is usually preferred. Young branchlets are notched by being cut halfway through. They are then bent downwards so that they hang limply. After a couple of months the branchlets have formed a callus, and the cutting is removed from the parent plant. It is then planted in sand under moderate shade. Roots will form in about a month.
In Africa the flowers are pollinated by night-flying insects. Out of its original areas pollination is often poor due to lack of suitable pollinators, but hand pollination is possible. If the plant is grown in orchards, it is usually grown in narrow hedges, because of its prickly nature. The access to the fruits, that grow on the top of the bush, is also made easier by using this method. It should be noted that the fruit is highly perishable, and the skin bruises easily.
Photographs taken in Picnic Bay, 2014
Page last updated 16th October 2016