Hibiscus acetosella (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Hibiscus acetosella Welwitsch ex Hiern

Protologue: Cat. Afr. Pl. Welwitsch 1(1): 73 (1896).

Family: Malvaceae

Chromosome number: 2n= 4x= 72

Synonyms

• Hibiscus eetveldianus De Wild. & Th. Durand (1899).

Vernacular names

• False roselle, red-leaved hibiscus, bronze hibiscus (En)
• Fausse oseille de Guinée (Fr)
• Indonesia: gamet.

Origin and geographic distribution

False roselle is of African origin and was possibly domesticated in Angola or Zaire. It is only known as a cultivated plant. It is well-distributed throughout tropical Africa and must have been introduced as a vegetable or as an ornamental plant into South-East Asia, occasionally found wild.

Uses

The leaves and young shoots are eaten as a side-dish with rice. They are sour in taste and slightly mucilaginous, and for this reason are added in small quantities to numerous dishes. False roselle is sometimes grown as a colourful temporary hedge. The stem yields a fibre of good quality, but seemingly not in profitable quantity. The red forms are popular ornamentals, also grown as frost-tender annuals in cool-temperate regions.

Production and international trade

False roselle is mainly produced in home gardens for domestic consumption.

Botany

• Annual or short-lived perennial herb or shrub, 0.5-2.5 m tall, little-branched, unarmed, usually entirely red or with a marked red flush.
• Leaves alternate, slightly fleshy, glabrous; petiole dark red, 0.5-10 cm long; leaf-blades broadly orbicular-ovate in outline, 2-12 cm × 2-12 cm, the lower ones deeply palmately 3-5-parted or lobed, the upper ones undivided and rhomboid, at base 5-7-nerved, margins irregularly serrate-crenate, above bronze-green to red, beneath usually red with a distinct nectary at the base of the midrib.
• Flowers solitary, axillary; pedicel up to 1 cm long; epicalyx segments 8-10, narrowly spathulate, 1-2 cm long, spreading, with an erect, linear, 3-4 mm long appendage, with scattered stiff hairs; calyx campanulate, regularly 5-cleft, 1.5-2 cm long, each lobe outside stiff-hairy on the nerves and on the centre of the midrib, with an oblong nectary, after flowering closely enveloping the capsule, accrescent to 2.5 cm; corolla wine-red with a dark purple centre, 3-7.5 cm in diameter; petals 5, obliquely obovate, 2-4 cm × 1.5-3.5 cm, apex rounded, base fleshy and narrowed, glabrous, above the dark red basal spot with distinct radiating veins; staminal column erect, 1-2 cm long, dark red, throughout its length beset with brown, shortly stalked anthers; style arms 5, 3-5 mm long, hardly exserted from the staminal tube, each ending in a discoid, dark red long-hairy stigma.
• Fruit an ovoid capsule, 1-2.5 cm × 1-1.5 cm, very acute, densely tuberculate, hispid, red, many-seeded.
• Seed reniform to globular, 3-5 mm in diameter, dark brown when ripe, verruculose.

The flower structure favours self-pollination, but some outcrossing by insects may occur. Cultivar "Red Shield" has brilliant maroon leaves.

H. acetosella (2n= 72) is most probably an allotetraploid derived from H. asper Hook.f. (2n= 36) and H. surattensis L. (2n= 36). H. asper is a wild plant from tropical Africa, sometimes cultivated for its fibres. H. surattensis is a wild plant of tropical Africa and Asia, also cultivated for its edible young leaves and for its fibres (see chapter on Minor Vegetables).

Ecology

False roselle is generally encountered in home gardens, but also as an escape in waste places and on roadsides. Because of insufficient care, it usually remains small, sometimes hardly 15 cm tall. It grows on all kinds of soils, but requires good drainage. In Java (6-8 °S) year-round flowering has been reported as well as seasonal flowering (plants remaining vegetative under the long-day conditions of December to March).

Agronomy

False roselle is propagated by seed, but multiplication is also possible by means of stem cuttings. Because of the scarcity of commercial plantings, little is known about cultural requirements and practices. They are probably rather similar to those of roselle (Hibiscus sabdariffa L.). Soilborne diseases such as Rhizoctonia solani and Sclerotium rolfsii are reported to cause plant losses.

Genetic resources and breeding

Germplasm is maintained at the International Jute Organization (IJO), Dhaka, Bangladesh. No selection work for vegetable use has ever been undertaken. H. acetosella has been the subject of in-vitro propagation studies. In tissue culture it is considered as relatively fast-growing. Plant regeneration through embryogenesis from callus gives good results.

Prospects

False roselle will remain a common home garden vegetable. Because of similar uses as roselle, a comparative study of H. acetosella and H. sabdariffa L. would be very useful to determine other similarities and differences.

Literature

• Lim-Ho Chee Len & Lee Sing Kong, 1988. In vitro propagation of some shrubs at the Singapore Botanic Gardens. Biotrop Special Publication 35: 197-207.
• Reynolds, B.D. & Blackman, W.J., 1983. Embryogenesis and plantlet regeneration from callus of Hibiscus acetosella. Journal of the American Society of Horticultural Science 108(2): 307-310.
• Stevels, J.M.C., 1990. Légumes traditionnels du Cameroun, une étude agro-botanique [Traditional vegetables of Cameroun, an agro-botanic study]. Thesis. Wageningen Agricultural University Papers 90-1, Wageningen, the Netherlands. pp. 172-177.
• van Borssum Waalkes, J., 1966. Malesian Malvaceae revised. Blumea 14(1): 59-60.

Authors

• S.H. Widodo