The water lemon vine is a moderately vigorous climber, to 32 ft (10 m) or more, its twining, more or less woody or wiry stems longitudinally grooved and bearing slender, tough tendrils in the leaf axils flanked by 2 slim, green stipules. The alternate leaves are oblong-ovate or elliptical, rounded at the base, abruptly pointed at the apex; 6 to 8 in (15-20 cm) long, 1 1/3 to 3 1/8 in (3.4-8 cm) wide; thick and leathery. The fragrant, solitary, 5-petalled flowers, 3 to 4 in (7.4-10 cm) across, have a bell-shaped calyx, oblong, red or purple-red sepals and petals, and corona filaments 6-ranked, banded with red, blue, purple and white. The fruit is ellipsoidal or ovoid, 2 to 3 1/8 in (5-8 cm) long, 1 1/2 to 2 3/8 in (4-6 cm) wide; orange-yellow; clasped at the base by 3 large, green, leaflike bracts, toothed and edged with conspicuous glands. The rind is leathery, to 1/8 in (3 mm) thick, white and spongy within; becomes hard when dry. Pleasantly rose-scented, the translucent, nearly white pulp is juicy, mucilaginous and of agreeable, subacid flavor, and encloses numerous seeds, flat and minutely ribbed.
Origin and Distribution
The water lemon is native to tropical America and common, wild and cultivated from southern Venezuela, Surinam, Guyana and French Guiana down through the Amazon region of Brazil to Peru. In the dry season, the fruits are regularly sold in local markets. The vine is cultivated and naturalized from Trinidad and Barbados to Jamaica, Puerto Rico, Hispaniola and Cuba. In Bermuda, it is only occasionally grown. It was introduced into Malaya in the 18th Century; is commonly cultivated in the lowlands and naturalized in Singapore and Penang. According to Petelot, the water lemon is grown in Thailand and throughout the southern half of Vietnam. In India, Ceylon and Hawaii, the vine is grown as an ornamental but rarely fruits except in hot, dry situations where the pollen is dry enough to be naturally transmitted. There are only a few specimens in Florida.
The water lemon flowers open only in the afternoon, and apparently are not self-pollinated, or only slightly so. Cross-pollination is required for good crops. If carpenter bees are not present at the right time, the pollen must be transferred by hand.
A warm, dry atmosphere is essential for early ripening of the stigmas. On Oahu, Hawaii, best yields have been obtained at sea-level, though the vine grows vigorously up to 1,500 ft (457 m).
The vine has grown and flowered well on sand and on limestone in Florida.
The water lemon grows readily from seeds or cuttings.
Trials have shown that the vine is fairly resistant to rootknot nematodes in Florida.
Children and adults make a hole in one end of the fruit and suck out the pulp and seeds for refreshment. The juice of the strained pulp makes an excellent beverage.
The pulp contains 1.55 mg of pantothenic acid per 100 g; the rind, 1.87 mg. This element belongs to the vitamin B complex group and is sometimes called vitamin B5.
The rind, leaves and seeds contain a cyanogenic glycoside. On the other hand, the leaves possess 387 mg, per 100 g, ascorbic acid. The leaf decoction is taken as a vermifuge. The seeds have a sedative action on the nervous system and heart and, in strong doses, are hypnotic. The root acts as a very potent vermifuge.