Carissa macrocarpa Prostrata

Carissa macrocarpa (grandiflora) 'Prostrata' is a curious form of Natal Plum with a low, spreading, and dense habit. This South African bush, not very hardy, produces edible fruits when ripe, which are similar in size and shape to our plums. It is armed with sharp prickles, has small persistent leathery leaves, and a long pleasantly scented flowering. Its small white flowers resemble those of jasmine, both in structure and fragrance, especially noticeable at night. In mild climates, especially near the sea, this plant makes an elegant and unusual ground cover. It adapts well to container cultivation, allowing it to be placed on the terrace and protected from frost in winter.

Carissa macrocarpa is an evergreen bush belonging to the Apocynaceae family, just like Oleanders, star jasmine (Trachelospermum jasminoides), and... periwinkle. It is native to the eastern coast of South Africa, where it grows on the edge of evergreen forests. Our plum and Natal plum do not belong to the same botanical family at all, and the 'plums' of our Carissa contain several seeds that are strongly recommended not to be ingested. The 'Prostrata' form, as its name suggests, has a rather creeping growth and horizontal stems. When mature, the plant measures about 60cm (23.6in) in height, spreading at least 80cm (31.5in). When grown in the ground, its dimensions can be slightly larger. Its growth rate varies depending on the cultivation conditions: in rich, moist, and deep soil, it will be more vigorous than in sandy, poor, and salt-rich soil. Its highly branched stems have long bifid, sharp spines that can measure 4 to 5cm (1.6 to 2in) in length and are greyish in colour. The evergreen foliage is composed of small rounded, thick, dark green shiny leaves on the upper side and lighter and matte green on the underside. They are densely arranged on the branches, almost imbricate. The flowering period is particularly long, from May to September. From twisted flower buds to the right, small white flowers with a diameter of 3cm (1.2in) open, composed of a tube widening into 5 lanceolate petals arranged in a star shape. Their fragrance, mainly nocturnal, attracts pollinators that work at night. The fruit is fleshy, smooth, oval to oblong, measuring 4 to 6cm (1.6 to 2.4in) in length and 2 to 4cm (0.8 to 1.6in) in width. It is ripe and edible when it turns a magenta to violet red colour. Juicy, sweet, rich in vitamin C, and with a mild flavour, it contains about fifteen small brown and flat seeds, toxic when ingested. These lovely 'plums' can be used to make delicious jelly.

Resistant to drought and salt spray, but not very hardy (down to -4 or -5°C), the Natal Plum 'Prostrata' is well suited for coastal areas, from the Mediterranean coast to the Atlantic coast unaffected by severe frosts. Its formidable spines require keeping it away from high-traffic areas and young children. It can be used in front of evergreen hedges at the edge of the garden, along with Griselinia littoralis, myrtles, and Oleanders. It adapts well to container cultivation, which can be placed on the terrace or balcony. This cultivation method allows gardeners in colder regions to protect it from severe frosts in an unheated greenhouse or conservatory in winter. Its height will be less significant in pots, but the plant will quickly fill the available space by spreading out.