Hibiscus cannabinus L.
Family
Malvaceae
Synonyms
Hibiscus sabdariffa L. var. δ, Hibiscus sabdariffa L. subsp. cannabinus (L.) G. Panigrahi & S.K. Murti.
Vernacular Names
| Malaysia |
Kenaf. |
| English | Kenaf, Deccan hemp, Bimlipatam jute. |
| Indonesia | Kenaf, Java jute. |
| Thailand |
Po kaeo (central), po daai (northern). |
| French |
Kenaf, chanvre de Bombay, chanvre de Guinee. |
Geographical Distributions
Hibiscus cannbinus is of African origin; in most countries south of the Sahara, H. cannabinus is a very common wild plant and it is also widely grown as a vegetable or fibre crop. Angola may have been a primary centre of origin, but greatest morphological diversity is found in East Africa. Both H. cannabinus and roselle (H. sabdariffa L.) may have been domesticated as early as 4000 BC in Sudan. The date of initial introduction into India is unknown. References to H. cannabinus cultivation started to be published around 1800 and it first appeared on the London market as ‘Bimlipatam jute’ in 1901. India has remained as the country with the largest production of H. cannabinus with concentrations of cultivation in West Bengal and in coastal areas around Visakhapatnam (Andhra Pradesh) and Madras (Tamil Nadu). H. cannabinus was introduced into Indonesia from India in 1904. An extensive programme of H. cannabinus cultivation was initiated in the 1920s in the Caucasus region of the Russian Federation (former USSR) and from there, it was introduced into China in 1935. H. cannabinus production was also initiated after 1945 in e.g. the United States, Cuba and South America. H. cannabinus is now widespread in the tropics and subtropics, often cultivated as a fibre plant. In Malaysia, it is cultivated but does not grow wild.
Description
Hibiscus cannbinus is an erect annual herb, measures up to 2 m tall in the wild and up to 5 m in cultivars. The taproot is well-developed, measures up to 25 cm deep with lateral roots spread horizontally to 1 m and the adventitious roots on lowest stem section. The stem is slender and cylindrical. In cultivation, it is unbranched and smooth, prickly on wild accessions, entirely green, green with red or purple pigmentation, or red, sometimes lower half green and upper half pigmented.
The leaves are arranged alternate. The stipules are slender, measure 5-8 mm long and pubescent. The petiole is 3-30 cm long, finely pubescent on the adaxial surface and bristled on the abaxial surface. It is green to red. The blade measures 1-19 cm x 0.1-20 cm, and very shallowly to very deeply palmately 3-7-lobed on the lower stem. It is often unlobed on the upper stem or even bract-like near the apex. The base is wedge-shaped to cordate, with serrate or dentate margins and acuminate at apex. The upper surface is hairless but with a prominent nectary 3 mm long at the base of the midrib. The lower surface is hairy along the veins.
The flowers are axillary, solitary or sometimes clustered near the apex. They are bisexual, 5-merous and measure 7.5-10 cm in diametre. The pedicel is 2-6 mm long and articulated at the base. The epicalyx is with 7-8 linear bracteoles. It is 7-18 mm long and persistent. The sepal is bell-shaped with 5 acuminate, subcaudate lobes of 1-2.5 cm long (up to 3.5 cm in cultivars), persistent, green, bristly, characteristically white, woolly, arachnoid hairy especially near the base and margins, and with a prominent nectary gland on each midrib. The petal is large and showy, usually cream to yellow with red inner base or sometimes blue or purple. The petals are free, usually spreading, twisted clockwise or anticlockwise, obovate, measure 4-6 cm x 3-5 cm, and the outer side is stellate-pubescent. The staminal column is epipetalous and surrounds the style. It is 17-23 mm long, dark red, with numerous filaments 1-2 mm long and with 1-celled, yellow or red anthers. The pollen is spiny and spherical. The pistil is superior, 5-locular, ovoid, pointed and with villose ovary. Each locule contains many ovules that are arranged in 2 vertical rows. The red style is single and branches into 3-5 and with hairy arms 2-4 mm long. Each branch ends in a headed stigma.
The fruit is an ovoid, beaked capsule, measuring 12-20 mm x 11-15 mm and densely appressed pubescent. The beak which is 1 mm long contains 20-25(-35) seeds. The seeds are slightly kidney-shaped to triangular with acute angles, measuring 3-4 mm x 2-3 mm, ash grey or brown-black with light yellowish spot and brown hilum. Seedling is with epigeal germination.
Ecology / Cultivation
Hibiscus cannabinus has a wide range of adaptation to climate and soil, and is grown between 45°N and 30ºS. H. cannabinus plants are tolerant of daily temperature variation between 10°C and 50°C, but are killed by frost. It grows best where mean daily temperatures during the growing season are higher than 20°C and average monthly rainfall is 100-125 mm during the growing season. These conditions are met during the rainy season in the tropics and the wet summer season of the subtropics. H. cannabinus is a short-day plant: regardless of the time of planting, most cultivars remain vegetative until the daylight period falls below 12.5 hours. Cultivars planted at a latitude of 20ºN will, therefore, not start flowering before early September. At higher latitudes, flowering commences progressively later, whereas at the equator, plants flower early and attain insufficient height, except when the grown cultivar is photo-insensitive.
H. cannabinus can be grown on a wide range of soils, but thrives best on free-draining sandy loams of alluvial or colluvial origin, with pH 6-6.8. It is salt-tolerant, but sensitive to waterlogging.
Line Drawing / Photograph
References
- Plant Resources of South-East Asia No.17: Fibre plants.
