Hibiscus abelmoschus L.

A variable, annual or biennial, erect herb or undershrub, 0.5-3.5 m tall, hispid, often woody at base, with taproot or tuberous root; stem usually solid, sometimes hollow; stem apices and petioles with many obliquely downwardly directed long sharp bristles, rarely sparsely hairy or glabrous. Leaves alternate, extremely variable in shape and size; petiole 6-30 cm long; stipules linear-filiform, simply hairy; lower leaves orbicular to transversely elliptical in outline, 6-22 cm x 8-24 cm, base cordate, angular or 3-7-palmately lobed or parted; higher leaves usually narrower and often hastate or sagittate, lobes spreading, oblong-lanceolate, coarsely serrate-dentate, rarely entire, both surfaces hispid with simple hairs and usually also minute stellate hairs, rarely glabrous. Flowers axillary, solitary; pedicel 2-19 cm long, somewhat accrescent; epicalyx segments (4-)7-10(-16), free, persistent, linear-lanceolate or oblong, 0.75-2.5 cm long, not enveloping the entire fruit as a lattice and much shorter, usually acute, simply hairy; calyx spathaceous, apex 5-toothed, splitting on one side during expansion of the corolla, adnate to and falling with the corolla, outside stellate-tomentose, inside simply sericeous; petals 5, obovate, 3.5-10 cm x 2.5-5.5 cm, yellow with crimson centre or white to red, with scattered gland-hairs or glabrous, apex rounded, base fleshy and ciliate with simple hairs; staminal column much shorter than the petals, antheriferous throughout, usually yellow, but dark purple at base, glabrous; ovary ovoid, 5-celled, hirsute; style 1, distally 5- branched but branches sometimes united to various degree, hairy; stigmas discoid. Fruit a loculicidally dehiscent, many seeded, ovoid or globose capsule, 2-8 cm long, occasionally fusiform, acuminate with a short rostrum, somewhat angular, usually hispid with simple stiff hairs, often also with short simple hairs and minute stellate hairs, rarely glabrous, black or dark brown; valves chartaceous or coriaceous, inside smooth and shining. A. moschatus is a very variable species with many synonyms and subclassifications. At present 3 subspecies are distinguished: -subsp. biakensis (Hochr.) Borss. A stout herb or undershrub, up to about 2 m tall, minutely stellate-hairy, with a long slender taproot; stem usually hollow; leaves large, orbicular, 10-19 cm in diameter, palmatilobed; petiole 6-13 cm long; pedicel very long and stout, after flowering up to 19 cm x 3-4 mm; epicalyx segments 8, lanceolate, 15-20 mm x 3-4 mm, in fruit appressed; corolla white or yellow with dark purple centre; capsule 5-8 cm long, with coriaceous valves; seed subglabrous. Distributed in New Guinea, possibly also cultivated as a vegetable. -subsp. moschatus. A stout herb or undershrub, up to about 1.5 m tall, with a long, slender taproot; stem usually retrorsely hispid; pedicel 3-8 cm long; epicalyx segments 6-10, 8-20 mm x 1-2.5 mm, in fruit appressed; corolla yellow with dark purple centre; capsule 5-8 cm long, thinly hispid, with chartaceous valves; seed subglabrous. In this subspecies 2 varieties can be distinguished: -var. betulifolius (Mast.) Hochr. Stem mostly glabrous, spotted red, hollow; epicalyx segments 6-8, lanceolate, 17-25 mm x 2.5-5 mm. Distributed in Indo-China, in Malesia rare. -var. moschatus. Stem always hispid, mostly evenly tinged red, rarely hollow; epicalyx segments 7-10, linear, 8-15 mm x 1-2 mm. Distribution as given for the species. -subsp. tuberosus (Span.) Borss. An erect or decumbent herb up to 75 cm tall with a short, tuberous, turgid taproot; stem usually patently hairy, sometimes prickly; epicalyx segments 9-10, in fruit spreading or reflexed, never appressed; corolla usually white or pink, sometimes yellow; capsule 2-5 cm long, densely hispid; seed ferrugineously tomentose. Distributed in Indo-China, Hainan, Malesia and northern Australia. A. moschatus subsp. moschatus is tetraploid (2n = 72); subsp. tuberosus is diploid (2n = 36).

In India the first flowers of A. moschatus are formed in the axil of the 3rd to 8th leaf depending on the cultivar. The first buds are formed 25-39 days after germination. Flower buds take 22-25 days to reach full bloom and flowering continues for 45-80 days. Anthesis occurs between 9 a.m. and 11 a.m. and the stigma is receptive on the day of anthesis. The fruit takes about 25 days from setting to maturity.

Thrives in fertile loamy or sandy-loamy soil. Growth is often poor on clay and sandy soils and on saline or strongly alkaline soils. Waterlogging is not tolerated.

A. moschatus can grow in a variety of places, e.g. roadsides, brushwood, fallow land, and on the bunds of rice fields. In the tropics it occurs up to 1650 m altitude in Indonesia, while in India it is cultivated up to 1000 m. A. moschatus requires a humid tropical or subtropical climate, although heavy and continuous rain affects crop growth negatively. The optimum temperature for vegetative growth is about 20-28 deg. C, but it can tolerate temperatures up to 45 deg. C. Frost is not tolerated. It is daylength sensitive, short days promoting early flowering. Flowering is also stimulated by low night temperatures. During flowering and fruiting dry weather is preferred. Subsp. biakensis grows near beaches, subsp. tuberosus prefers locations with an annual dry period and where the vegetation is periodically burnt.

A. moschatus is cultivated commercially in Java, India (mainly in the Deccan and Carnatic), Madagascar and in parts of Central and South America. On a small scale it is cultivated and occasionally occurs as a weed throughout the tropics and in warm temperate areas.

A. moschatus is propagated by seed. It requires a fine but compact seedbed for uniform germination. In India about 5 kg/ha of seed are used for sowing in rows spaced 75-90 cm apart. When the seed is dibbled at a spacing of 90 cm x 90 cm, 1-1.5 kg/ha is needed. Soaking the seed in water overnight accelerates germination. Seed is sown 1-2 cm deep. Under favourable conditions, germination starts 4-15 days after sowing and is complete after 15-30 days. The optimum temperature for germination is about 30 deg. C. The germination rate of good commercial seed is about 85%.

In row planting, thinning is required; in India it is done to about 60 cm, in China to 45-50 cm between plants. Husbandry: A. moschatus needs to be weeded 2-3 times during early growth. Later, the superficial root system may be damaged by hoeing. In northern India where lush vegetative growth often leads to poor fruit set, pruning 50-60 days after transplanting tended to increase seed yield by about 40%. Earlier pruning was not beneficial. In a fertilizer trial in India on a sandy loam poor in P and rich in K, seed yield increased from 0.5 to 1.2 t/ha in response to an application of 120 kg N/ha, while a yield of 1.5 t/ha was obtained with 120 kg N/ha in combination with 35 kg P/ha.

Diseases: A. moschatus suffers from several diseases, the most important being Hibiscus mosaic virus (HMV), anthracnose and leaf spot. Plants infected with HMV should be uprooted and destroyed as there is no other effective control. Anthracnose, caused by Colletotrichum hibisci, affects all plant parts and may start in the seedling stage. Seed treatment and spraying with fungicides, e.g. Bordeaux mixture, can control the disease. Alternaria leaf spot and Phytophthora leaf blight can cause damage, the latter especially under humid conditions. Seed treatment can reduce losses. Pests: In India, spotted bollworm (Earias insulana) attacks the crop during vegetative growth and the fruiting stage. Infested shoots turn brown above the point of infestation, bend down and die. Fruits are also affected. Preventive spraying with thiodan at 10--15 day intervals from the seedling stage until harvesting effectively controls the pest, but is rarely practised by small farmers. Pink bollworm (Pectinophora gossipialla) causes some damage to pods and seeds in northern India. A cotton semilooper (Anomis flava) is observed in India during the rainy season, the intensity of attack decreases as temperatures become lower, and the pest disappears in mid-November.

The weight of 1000 seeds is about 13 g.

Ornamental: A. moschatus is sometimes grown as an ornamental.

Other products: A. moschatus is the source of ambrette seed oil used in luxury perfumery, cosmetic products and as an additive in the preparation of some kinds of chewing tobacco, baked products, sweets, alcoholic (e.g. vermouth and bitters) and non-alcoholic drinks. Arabs sometimes flavour their coffee with the seed. The leaves are sometimes used by Malay people as wrappers for parcels. The mucilage from the roots is used in China for sizing paper. Seeds are burned as incense and used in making incense sticks (agarbattis). Essential oils: In India and Malaysia pounded seeds are used to perfume hair. Food: Tender leaves, shoots and pods are occasionally eaten as vegetable. Medicine: A. moschatus has many applications in traditional medicine. In the Philippines a decoction of the roots and leaves is taken as an emollient remedy for gonorrhoea and rheumatism, while in Burma (Myanmar) and the Philippines the seed is said to have stomachic, tonic, diuretic, antihysteric, stimulating and antispasmodic properties. In Indonesia pulverized seeds mixed with powder provide a useful remedy to treat prickly heat. In Indo-China the root is said to be effective in the treatment of blennorrhagia and leucorrhoea, the leaves and flowers are rubbed on scabies and applied as poultice to swellings. In traditional Vietnamese medicine the plant is used as an antivenom and a diuretic. It is also said to be an aphrodisiac. The tuberous roots of A. moschatus subsp. tuberosus (Span.) Borss. are said to be sought after by the Chinese as a substitute for ginseng. Fibre: Fibre from the stem is a substitute for jute, but offers no advantages over the latter. Poison: The seeds placed between clothes to keep away insects.