The flowers are 8–10 cm (3–4 in) in diameter, white to pale yellow with a dark red spot at the base of each petal, and have a stout fleshy calyx at the base, 1–2 cm (0.39–0.79 in) wide, enlarging to 3–3.5 cm (1.2–1.4 in), fleshy and bright red as the fruit matures. It takes about six months to mature.
Uses
The plant is considered to have antihypertensive properties. Primarily, the plant is cultivated for the production for bast fibre from the stem of the plant. The fibre may be used as a substitute for jute in making burlap Hibiscus, specifically Roselle, has been used in folk medicine as a diuretic, mild laxative, and treatment for cardiac and nerve diseases and cancer.
The red calyces of the plant are increasingly exported to America and Europe, where they are used as food colourings. Germany is the main importer. It can also be found in markets (as flowers or syrup) in some places such as France, where there are Senegalese immigrant communities. The green leaves are used like a spicy version of spinach. They give flavour to the Senegalese fish and rice dish thiéboudieune. Proper records are not kept, but the Senegalese government estimates national production and consumption at 700 t (770 short tons) per year. Also in Myanmar their green leaves are the main ingredient in making chin baung kyaw curry.
In East Africa, the calyx infusion, called "Sudan tea", is taken to relieve coughs. Roselle juice, with salt, pepper, asafetida and molasses, is taken as a remedy for biliousness.
The heated leaves are applied to cracks in the feet and on boils and ulcers to speed maturation. A lotion made from leaves is used on sores and wounds. The seeds are said to be diuretic and tonic in action and the brownish-yellow seed oil is claimed to heal sores on camels. In India, a decoction of the seeds is given to relieve dysuria, strangury and mild cases of dyspepsia. Brazilians attribute stomachic, emollient and resolutive properties to the bitter roots.
Medicinal uses
Many parts of the plant are also claimed to have various medicinal values. They have been used for such purposes ranging from Mexico through Africa and India to Thailand. Roselle is associated with traditional medicine and is reported to be used as treatment for several diseases such as hypertension and urinary tract infections. There is currently insufficient evidence to demonstrate any beneficial effect of roselle on raised blood pressure or on blood lipid lowering. although experimental results seem contardictory. It may lower BP in pre- and mildly hypertensive adults. A recent (2007)clinical trial demonstrated important antihypertensive effectiveness Another trial,in 2009,on sixty diabetic patients with mild hypertension found that Hibiscus sabdariffa infusion had positive effects on BP in type II diabetic patients with mild hypertension.
Hibiscus sabdariffa has shown antimicrobial activity against E. coli.
A recent review stated that H. sabdariffa extract exhibits activities against atherosclerosis, liver disease, cancer, diabetes and other metabolic syndromes
Phytochemicals
The plants are rich in anthocyanins, as well as protocatechuic acid. The dried calyces contain the flavoanids gossypetin, hibiscetine and sabdaretine. The major pigment, formerly reported as hibiscin, has been identified as daphniphylline. Small amounts of myrtillin (delphinidin 3-monoglucoside), Chrysanthenin (cyanidin 3-monoglucoside), and delphinidin are also present. Roselle seeds are a good source of lipid-soluble antioxidants, particularly gamma-tococherol.
