The genus Hibiscus (Malvaceae) includes more than 300 species of annual or perennial herbs, shrubs or trees (Wang, Morris, Tonnis, Davis, & Pederson, 2012). Hs (syn.: Abelmoschus cruentus (Bertol.) Walp., Furcaria sabdariffa Ulbr., Hibiscus cruentus Bertol., Hibiscus fraternus L., Hibiscus palmatilobus Baill. and Sabdariffa rubra Kostel (The Plant list, 2010) is commonly known as roselle, hibiscus, Jamaica sorrel or red sorrel (English) and in Arabic, karkadeh (Ali et al., 2005; Ross, 2003). Its native distribution is uncertain, some believe that is from India or Saudi Arabia (Ismail, Ikram, & Nazri, 2008), while Murdock (Murdock, 1959) showed evidence that Hs was domesticated by the black populations of western Sudan (Africa) sometime before 4000 BC. Nowadays, it is widely cultivated in both tropical and subtropical regions (Morton, 1987; USDA, 2007) including India, Saudi Arabia, China, Malaysia, Indonesia, The Philippines, Vietnam, Sudan, Egypt, Nigeria and México (Chewonarin et al., 1999; Dung et al., 1999; Eslaminejad & Zakaria, 2011; Ismail, Ikram, & Nazri, 2008; Mahran, El-Hossary, & El-Labban, 1979; Rao, 1996; Sharaf, 1962; Yagoub Ael, Mohamed, Ahmed, & El Tinay, 2004). There are two main varieties of Hs, the first being Hs var. altissima Wester, cultivated for its jute-like fibre and the second is Hs var. sabdariffa. The second variety includes shorter bushy forms, which have been described as races: bhagalpuriensi, intermedius, albus and ruber. The first variety has green, red-streaked, inedible calyces, while the second and third race have yellow-green edible calyces (var. ruber) and also yield fibre (Morton, 1987).
Hs var. sabdariffa ruber is an annual, erect, bushy, herbaceous subshrub that can grow up to 8 ft (2.4 m) tall, with smooth or nearly smooth, cylindrical, typically red stems. The leaves are alternate, 3 to 5 in (7.5–12.5 cm) long, green with reddish veins and long or short petioles. The leaves of young seedlings and upper leaves of older plants are simple; lower leaves are deeply 3 to 5 or even 7 lobed; the margins are toothed. Flowers, borne singly in the leaf axils, are up to 5 in (12.5 cm) wide, yellow or buff with a rose or maroon eye, and turn pink as they wither at the end of the day. At this time, the typically red calyx, consisting of 5 large sepals with a collar (epicalyx) of 8 to 12 slim, pointed bracts (or bracteoles) around the base, begins to enlarge, becomes fleshy, crisp but juicy, 1 1/4 to 2 1/4 I. Da-Costa-Rocha et al. / Food Chemistry 165 (2014) 424–443 425 in (3.2–5.7 cm) long and fully encloses the velvety capsule, 1/2 to 3/4 in (1.25–2 cm) long, which is green when immature, 5-valved, with each valve containing 3 to 4 kidney-shaped, light-brown seeds, 1/8 to 3/16 in (3–5 mm) long and minutely downy. The capsule turns brown and splits open when mature and dry. The calyx, stems and leaves are acid and closely resemble the cranberry (Vaccinium spp.) in flavour (Morton, 1987; Ross, 2003).
Ali, B. H., Al Wabel, N., & Blunden, G. (2005). Phytochemical, pharmacological and toxicological aspects of Hibiscus sabdariffa L.: a review. Phytotherapy Research, 19(5), 369–375.
Wang, M. L., Morris, B., Tonnis, B., Davis, J., & Pederson, G. A. (2012). Assessment of oil content and fatty acid composition variability in two economically important Hibiscus species. Journal of Agricultural and Food Chemistry, 60(26), 6620–6626.
Ismail, A., Ikram, E. H. K., & Nazri, H. S. M. (2008). Roselle (Hibiscus sabdariffa L.) seeds nutritional composition protein quality and health benefits. Food, 2(1), 1–16.
Morton, J. F. (1987). Fruits of warm climates. Florida Flair Books.