Sparkling with white, starry flowers and smothered in scarlet fruit, the Natal Plum is one of the most eye-catching shrubs for the Mediterranean garden and greenhouse. Yet, gorgeous though it is, Carissa macrocarpa is a plant whose virtues are often overlooked.
Carissas Great And Small
The Carissas are a genus of shrubs and small trees distributed from Australia and Asia to Africa. Carissa macrocarpa belongs to the eastern Cape and Natal regions of South Africa, where it goes by the picturesque name of the Large Num-num. Its close relative, Carissa grandiflora, also hails from southern Africa.
Leaf, Thorn and Flower
A mature Natal Plum forms a dense, evergreen shrub up to 4 metres high, the young branches carrying dark green, opposite oval leaves which are glossy and leathery in texture. A particularly distinctive feature are the prominent, Y-shaped, double-pronged spines which make it such an effective hedging plant.
Natal Plums bloom year round but are especially floriferous between May and December in the Northern Hemisphere. The flowers are borne on the tips of the young branches, singly or in clusters, and can more than 4 cm across. Individually, the five-petalled flowers are exquisite and against the dark foliage, these snowy white stars shine in the summer sun. En-masse they are spectacular - a large bush can bear hundreds of these starbursts at any one time.
As if this isn´t enough, they have a truly voluptuous scent. Carissa, like many plants with white flowers, is primarily pollinated by night flying hawk moths and beetles but unlike other nocturnal blooms, the delicious perfume is present throughout the day.
Fruit
The Natal plum owes its common name to the oval fruits which follow the blooms. These are scarlet with darker streaks and are very attractive in their own right.
They are also highly edible. Cut into a ripe fruit and you reveal a bright pink, somewhat grainy flesh with 10-15 small flat brown seeds at the centre. Immature fruits exude a harmless white latex when sliced, which can be washed off the cut surfaces: all other parts of the plant are, however, reputed to be poisonous.
The raw fruit has an acidic flavour akin to cranberries and can be eaten raw in fruit salads. Nethertheless, it is as a cooked fruit that it is particularly versatile. Stewed with sugar, it makes an excellent pie filling and being rich in pectin it is perfect for making jelly. Cooking separates the latex which sticks to the sides of the pan (never use an aluminum vessel) but this is removed by applying vegetable oil. Whole fruits are preserved by pricking them, cooking in sugar syrup, and bottling.
Natal plums are healthy as well as versatile. They contain minerals, more Vitamin C than oranges, and are rich in anthocyanins, plant compounds reputed to have many health benefits.
Commercial and Ornamental Uses
Not surprisingly, this versatile plant has a long horticultural history. As early as the 19th century, the Natal Plum was being exploited as a fruit crop. Today it is grown for this purpose on a small scale in the USA, India and, of course, South Africa. Many varieties abound, with such names as "Gifford", "Fancy" and "Torrey Pines". Despite this, it has never gained universal popularity as a fruit and, in many countries, is virtually unknown.
Carissa macrocarpa is perhaps better known as an ornamental shrub. Dwarf and prostrate varieties, and types with fewer spines have been developed, and established cultivars include "Dainty Princess", "Nana" and "Boxwood Beauty". It is drought resistant and has flowers that easily match the temperamental Gardenias in appearance and fragrance. As a tough and impenetrable hedge, the spiny varieties are effective deterrents against trespassers. Even so, its potential remains largely overlooked and it is puzzling that it has not been utilized as a central highway reservation shrub in warm climates, in place of the ubiquitous Oleander.
Cultivation
In cooler regions, Carissa iseasily grown as a greenhouse shrub. Indoors or out, it is tolerant of erratic watering and different free-draining soils (although feeding with a standard balanced fertilizer is appreciated) and is suitable for coastal regions as it can tolerate a little salt. Site the plants in full sun and remember that they are frost tender. Despite this lack of hardiness, they are worth trying outside in the milder regions of Britain, such as Devon and Cornwall. Pests are not common, but red spider mite and mealy bug occasionally appear and should be dealt with promptly.
Propagation
The Natal Plum is easily grown from seed, which should be sown in free-draining compost and covered with a few millimeters of medium, then maintained at 20-25º C. They often germinate within two weeks and can flower within several years.
Cuttings are another option but require special attention. Young twigs should be selected on the bush then cut half way through. Left on the plant like this, they form a callus in two months, after which they can be removed and potted up in damp sand. if you are fortunate, they will root within a month. Given several good growing seasons, there is no reason why you should not soon be enjoying the lovely flowers and tasty fruit of this exceptional but greatly underrated shrubby beauty.
References
Bob Flowerdew: Undercover with Bob Flowerdew: 27 Natal Plums www.hartley-botanic.co.uk
Fruitpedia: Natal Plum (C. macrocarpa) www.fruitpedia.com
PlantzAfrica: Carissa macrocarpa www.plantzafrica.com
Purdue University Center for New Crops and Plant Products: Carissa: Carissa macrocarpa A. DC; Carissa grandiflora A. DC (Marton J 1987) www.hort.purdue.edu/newcrop/default.html
Peter Ashby - Peter Ashby lives near Granada in southern Spain, is an expert on natural history, and a dedicated traveller, writer and hispanist.
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