Local names:
English (Christ's thorn,Bengal currant), Filipino (perunkila,caraunda,caranda,caramba), Hindi (karaunda,karanda), Malay (kerenda,karaunda), Thai (namdaeng,nam phrom)
Carissa congesta is a rank-growing, straggly, woody, climbing shrub, usually growing to 3-5 m high, sometimes ascending to the tops of tall trees. Branches numerous and spreading, forming dense masses, set with sharp, simple or forked thorns, up to 5 cm long, in pairs in the axils of the leaves. Leaves evergreen, opposite, oval or elliptic, 2.5-7.5 cm long; dark-green, leathery, glossy on the upper surface, lighter green and dull on the underside. Flowers fragrant, tubular with 5 hairy lobes, twisted to the left in the bud instead of to the right as in other species; white, often tinged with pink, borne in terminal clusters of 2 to 12. Fruits in clusters of 3-10, oblong, broad-ovoid or round, 1.25-2.5 cm long; skin fairly thin but tough, purplish-red, turning dark-purple or nearly black when ripe; smooth, glossy; enclosing very acid to fairly sweet, often bitter, red or pink juicy pulp, exuding flecks of latex. There may be 2 to 8 small, flat, brown seeds. The name Carissa is probably derived from the Sanskrit ‘corissa’, a name for one of the Indian species of the genus.
Ecology
C. congesta is more cold-tolerant than the carissa (Carissa macrocarpa). It grows from sea-level to 600 m in the Philippines; but up to an altitude of 1 800 m in the Himalayas; its chief requirement is full exposure to sun.
Native range
India, Myanmar, Sri Lanka
Tree management
The plant grows slowly when young. Once well established, it grows more vigorously and becomes difficult to control. If kept trimmed to encourage new shoots, karanda blooms and fruits profusely.
C. congesta is more cold-tolerant than the carissa (Carissa macrocarpa). It grows from sea-level to 600 m in the Philippines; but up to an altitude of 1 800 m in the Himalayas; its chief requirement is full exposure to sun.
Propagation is usually by seed. Experimental work in India has shown that cuttings from mature plants may not root at all; 20% of hardwood cuttings from trimmed hedges have rooted in November but not when planted earlier. Cuttings from nursery stock gave best results: 10% rooted in late September; 20% in early October; 30% in late October; and 50% in early November. In all cases, cuttings were pre-treated with indolebutyric acid at 500 ppm in 50% alcohol. Tender tip cuttings could be rooted under constant mist, the karanda can be grafted onto self-seedlings.
Poison: A paste of the pounded roots serves as a fly repellant.
The unripe fruit is sour and astringent and is used for pickles. When ripe it is sweet and is used for tarts, puddings and jellies. The syrup has been successfully utilized on a small scale in soft drinks.
C. congesta leaves are fodder for the tussar silkworm.
It is used as fuelwood.
Timber: The white or yellow wood is hard, smooth and useful for fashioning spoons, combs, household utensils and miscellaneous products of turnery.
Tannin or dyestuff: The fruits have been employed as agents in tanning and dyeing.
Medicine: The unripe fruit is used medicinally as an astringent. The ripe fruit is taken as an antiscorbutic and remedy for biliousness. The leaf decoction is valued in cases of intermittent fever, diarrhoea, oral inflammation and earache. The root is employed as a bitter stomachic, vermifuge and an ingredient in a remedy for itches.
Ornamental: C. congesta is conspicuous when in starry bloom.
The plant has dense branches and sharp spreading thorns, and is suitable for fences.