Hibiscus sabdariffa L.

Herb, annual, 0.5-2 m high, the stem glabrous or sparsely puberulus. Leaves long-petiolate, the petiole up to 6.5 cm long, glabrous or sparsely puberulus, the stipules narrowly triangular, acute; blade polymorphic, simple and ovate-acute to usually 3-to 5-to 7-palmatifid, the lobes verry narrowly elliptic and acute, with acute sinuses, serrulate or crenulate at the margin, up to 12-15 cm long, glabrous, the midrib prominent and bearing a subbasal gland beneath. Flowers axillary, solitary or in racemiform, terminal inflorescences by reduction of the upper leaves, the pedicel short and stout, 5-7 mm long; epicalyx of ca 10 bractlets, these linear-ovate, united basally and adnate to the base of the calyx, ca 8-12 mm long, sparsely hirsute especially toward the base, accrescent; calyx cupuliform, lobed to about or to below the middle, 1.5-2.2. cm long, deep red, much accrescent, up to 3.5 cm long in fruit and becoming with the epicalyx fleshy and dark red or purple, the lobes ovate, acute, strongly 3-nerved, usually with an elongate gland on the midvein of each lobe, sparsely hirsute especially toward the base; petals cuneate-obovate, rounded at the apex, 3-5 cm long, cream-colored or yellow, often tinged with red; staminal tube much shorter than the corolla. Capsule much shorter than the accrescent calyx, subglobose, apiculate, 1.8-2 cm long, appressed-hirsute; seeds reniform-angulate, 3-5 mm long, very minutely puberulus.

A tropical plant. It grows from sea level up to about 1,700 m altitude. It will tolerate a range of soils. It requires short days for flowering. They will grow in semi arid locations. It grows best where average temperatures are in the range 25-30°. It needs a temperature above 10-13°C. It is very sensitive to frost. Plants will tolerate high temperatures. They grow up to 800 m altitude in Africa. A rainfall of 450-550 mm distributed over a 90-120 day growing period is required. It cannot tolerate waterlogged soils. It can grow in arid places. It suits hardiness zones 10-12. In XTBG Yunnan.

A commercial crop, Roselle is used as food, fibre and for its medicinal properties; see Carvajal-Zarrabal et al. (2012), Da-Costa-Rocha et al. (2014) and references therein. Cultivated for its fleshy calyces that are used to make jams and a refreshing infusion in hot water, it probably has been dispersed by people carrying ripe fruit and discarding the capsules at their camp sites. The species would seem to be one of the more useful recent additions to the Australian flora.

Seeds are sown and the seedlings can be transplanted. They are transplanted when 15-20 cm high. Seed should be planted 1-2.5 cm deep. A spacing of 50 cm x 50 cm is suitable although a wider spacing is used for fruit and a closer one for leaves. Plants can be propagated by cuttings.