Carissa macrocarpa

Description

A common constituent of coastal areas, this woody, spiny and densely twiggy, decorative shrub or small tree is often used to create first-class, impenetrable hedges in warmer, moist parts of the country. It is very attractive, with brilliant, deep green, shiny, thickly textured oval leaves that remain pleasingly green throughout the year, sweetly scented masses of starry, pure-white, jasmine-like flowers and bright scarlet, nutritious, fleshy fruits that are readily pulled to pieces by animals. New growth is striking, being a glittering, coppery green, and the numerous stout thorns the plant is endowed with are arranged in neat, forked pairs. It exudes milky white sap from broken limbs, and it a highly ornamental and useful addition to the garden. When in fruit and flower, it creates a truly dazzling and eye-catching display that often lasts for a long time.

SA Tree

Family

Apocynaceae (Dogbane family)
A family of trees, shrubs, woody vines and herbs belonging to the order of Gentianales, with more than 400 genera and 4500 species, found primarily in the tropical and subtropical areas of the world.
Many members possess a milky or watery latex, which is often poisonous, but is also used medicinally or as bird lime.
Leaves are typically simple and opposite, or arranged in whorls of 3 or more, with smooth, entire margins.
Flowers are small and grouped in clusters, rarely solitary, and the fruits are either berries or drupes, usually occurring in pairs but sometimes singly.
Many members are highly decorative, such as the Frangipani and Impala Lily (Adenium multiflorum).

Habitat

A predominantly coastal species of low elevations, seldom found far from the sea, common along the eastern seaboard of South Africa.
It naturally occurs on sand dunes and in coastal thickets in the Natal and Cape provinces, as well as the margins of evergreen and woodland forests.
It can survive outside its native range and is able to adapt to a wide range of climatic conditions.

Bark

A typically multi-stemmed plant, with somewhat rough, light-brown to grey bark.
The side branches are initially a pale greenish-brown, with longitudinal ridges and grooves, giving them a creased appearance.
It contains a milky white, toxic latex in nearly all parts, and has rigid, stout, once- or twice-forked thorns that can measure up to 50 mm each.

Foliage

Evergreen.
Simple, broadly ovoid to semi-rotund (20-60 x 15-40 mm), glabrous leaves, arranged in opposite pairs on the stems.
The leaves are a dark, shimmering green above, paler green below, and have a thickly rubbery texture.
The margins are smooth, and taper to a bristle-like tip, while the bases are somewhat square to rounded.
Conspicuous glands can be seen in the axils of the leaves, and the petioles are generally short (3-5 mm).
Venation is obscure.

Flowers

Rather large, white, often pink-tinged, starry flowers, occurring singly or in a few-flowered clusters at the ends of branchlets or at the base of the Y-shaped thorns.
The corolla-tube is up to 14 mm long, with spreading lobes that overlap to the left side, and the flowers have a diameter of up to 35 mm.
The flower tubes are often hairy within, and the flowers have a lovely, sweet scent, much like jasmine.
(July – November, but often flowers can be found all year round).

Fruit

Large (35-50 x 25-35 mm), oval, thin-skinned, fleshy fruits, exuding a non-toxic, thinly watery latex when broken.
The fruits are edible and contain numerous small brown seeds.
They mature from green to bright red.

Height

Spread

Practical

The edible fruits can be made into a delicious and nutritious (Vitamin C and essential minerals), preserve.

Warnings

The latex contained in the plant is toxic, and the ripe fruits are the only part that is safe for ingestion.

Wildlife

The brightly coloured fruits are rapidly pulled to pieces by many fructivorous birds, as well as monkeys, baboons and some smaller mammals.
The flowers, which have a sweet smell that intensifies as night approaches, lure a vast array of insect life and butterflies, and also provides food for honeybees. These insects will then attract insectivorous bird species.

Advantages

A striking, pleasant ornamental, with dark, lustrous foliage, bright red fruits and dazzling white flowers that form a striking contrast and can provide aesthetic appeal all year round.
It is a useful addition to very sandy or brackish soils in coastal gardens.
It can be trimmed down to form a thick, evergreen hedge or shaped to become a small, dainty tree.
It is hardy, adaptable, water-wise, and does not have an aggressive root system.
Suitable for container planting, will survive in shady areas, responds well to pruning, and makes a lovely bonsai subject.
Planed as a single specimen or a focal point it is sure to attract attention.
They make lovely, decorative hedges, both formal and informal, and are a good choice for neat hedges in parking areas.
It makes a solid, nearly impenetrable, thorny security barrier or hedge, and if intended for this purpose, it needs to be planted about 1 metre apart.it will form an effective, sturdy hedge in about 3 years.
Over time, it will make a dense, decorative screen, and it can be grown in difficult coastal and smaller, townhouse gardens, or areas with limited space.
It is evergreen, so it will remain lush all year round, and attracts a host of wildlife to any garden.
Also, a good candidate for filling gaps in the garden where other vegetation struggles.

Tolerance

The plants naturally thrive in areas where the daytime temperature can be quite high (10 – 35°c), and rainfall is moderate to good.
They are however a somewhat water-wise species and can withstand periods of drought.
As they originate from coastal areas, they are able to tolerate salt-spray, and the strong winds accompanying it, as well as saline soils.
They are sensitive to frost damage, especially when young, and are more suited for warmer gardens.
Despite the fact that they are frost tender, they can be grown successfully in colder areas if given adequate protection when young and planted in a sheltered position, but growth may be slower.
Gaurd against extreme fluctuations in temperature for at least the first 3 -4 years.

Growth Rate

Under ideal conditions, a rate of 500-700 mm per year can be expected.
If propagated from seed, first flowering will occur at about 5 years of age, and more or less 3 years if reproduced from cuttings.

Lighting

Can be grown in full sun or light, partial shade. Flowering and fruiting may be poor in overly shady conditions.

Soil & Water

Carissa grows best in a well-drained and well aerated, nutrient rich, peaty or loamy soil, with a slightly more acidic ph.
It will accept nutrient poor, very sandy soils, and has adapted to saline soils.
It has moderate water needs, and does not respond well to waterlogged soils, as it is prone to developing root rot.
A well-drained soil will help prevent this.

Propagation

Sow the seeds in spring or early summer, in a well-drained mixture of compost and fine, washed river sand (1:2), after treating them with a pre-emergence fungicide.
Cover the seeds with an additional thin layer of sand.
Place in a warm, bright area (not direct sunlight), and keep the soil moist, but not overly wet.
Semi-ripe, hard or softwood cuttings of actively growing side shoots can be taken, and then treated with a rooting hormone.
Place in a similar growing medium, and mist often.
Regular trimming of your plant will encourage more prolific flowering and fruiting