Common Name: Roselle

General Information

Hibiscus sabdariffa is an erect, mostly branched, annual to perennial plant growing up to 4.5 metres tall. The stems often become woody, at least at the base, and persist for more than a year[, , ].
An important multipurpose plant supplying a range of foods, medicines and other products It has been grown as a food crop for around 6,000 years and is still widely cultivated in both tropical and sub-tropical zones both for food and for its fibre. There are some named varieties[]. The plant is also grown as an ornamental, valued especially for its decorative red stalks[]. The plant, especially the calyces, is traded internationally.

Known Hazards

The oil might contain toxic substances[].

Botanical References

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Range

Tropics - probably tropical central or western Africa.

Habitat

Disturbed ground[]. Savannah grassland and open woodland[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual/Perennial
Height	3.00 m
Pollinators	Insects, Self
Self-fertile	Yes
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Roselle is best suited to lowland, humid, tropical climates, where it is found from sea-level to elevations of about 600 metres[]. It grows best in areas with a well-distributed annual rainfall of 1,500 - 2,000 mm, though it can tolerate an annual rainfall of 640 - 4,290mm, and an annual temperature in the range of 12.5 - 27.5°c[].] It tolerates a warmer and more humid climate than the related kenaf (Hibiscus cannabinus), but is more susceptible to damage from frost and fog[].
Prefers a well-drained humus rich fertile soil in full sun[]. For best yields, roselle requires a permeable soil, a friable sandy loam with humus being preferable; however, it will adapt to a variety of soils[]. It is not shade tolerant and must be kept weed-free[]. It will tolerate floods, heavy winds or stagnant water[]. Prefers a pH in the range of 4.5 to 8.0[]. Because of their deep root system, plants can tolerate some drought[].
Plants are sensitive to the length of daylight and do not flower if there are more than 13 hours of light in the day[]. Plants exhibit marked photoperiodism, not flowering at shortening days of 13.5 hours, but flowering at 11 hours. In the United States plants do not flower until short days of late fall or early winter. Since flowering is not necessary for fibre production, long light days for 3 - 4 months is the critical factor[].
Harvesting can begin about 3 - 5 months after sowing the seed[]. Yields of 10 tonnes per hectare of leaves can be obtained and 8 tonnes of calyces[].
There are two main varieties of the plant:-
Hibiscus sabdariffa sabdariffa has long branches and usually grows up to 1.5 metres tall. It produces red or pale yellow inflated edible fleshy calyces but a poor quality fibre[, , ].
Hibiscus sabdariffa altissima is unbranched or has short branches and can be up to 4.5 metres tall. The fibre is of good quality but the calyces are leathery and inedible[, , ].
Each variety has various cultivars. The best known of the edible forms arre: 'Victor', 'Rico' and 'Archer'[]. There is also a green form known as the white sorrel, with greenish-white fruits[].
Plants have a deep penetrating taproot[]. Plants are resistant to root-knot nematodes[].
Hybridizes in the wild with Hibiscus cannabinus[].

Edible Uses

The fresh calyx (the outer whorl of the flower) is eaten raw or cooked. It is rich in pectin and citric acid[]. It is eaten in salads, is cooked and used as a flavouring in cakes etc and is also used in making jellies, soups, sauces, pickles, puddings etc[, , , ]. An acid flavour and mucilaginous texture[]. The calyx is rich in citric acid and pectin and so is useful for making jams, jellies etc[, ]. It is used to add a red colour and flavour to herb teas[, ], and can also be roasted and used as a coffee substitute[]. The flowers are produced all year round[].
There are two types of calyx - green and red. The green is more commonly used as a vegetable, whilst red types are more likely to be used as a colouring and to make an acid-flavoured drink[]. A refreshing and very popular beverage can be made by boiling the calyx, sweetening it with sugar and adding ginger[].

Tender young leaves and stems - raw or cooked[, , ]. Used in salads, as a potherb and as a seasoning in curries, they have an acid, rhubarb-like flavour[, , ].

Seed - roasted and eaten as a snack, or ground into a powder then used in oily soups and sauces[, ].

The roasted seeds have been used as a coffee substitute that is said to have aphrodisiac properties[].

Root - it is edible but very fibrous[]. Mucilaginous, without very much flavour[].

The seed yields 20% oil[]. The seeds yield 17% of an edible oil[]. The oil might contain some toxic substances[].

Medicinal

Roselle is an aromatic, astringent, cooling herb that is much used in the Tropics. It is said to have diuretic effects, to help lower fevers and is antiscorbutic[, ].

The leaves are antiscorbutic, emollient, diuretic, refrigerant, and sedative[]. The leaves are very mucilaginous and are used as an emollient and as a soothing cough remedy[].
The leaves are used externally as a poultice on abscesses, sores and ulcers[, ]. The juice is used as a treatment for conjunctivitis[].

The fruits are antiscorbutic[].

The flowers contain gossypetin, anthocyanin, and the glycoside hibiscin[]. These may have diuretic and choleretic effects, decreasing the viscosity of the blood, reducing blood pressure and stimulating intestinal peristalsis[, ]. The leaves and flowers are used internally as a tonic tea for digestive and kidney functions[, ].

The ripe calyces are diuretic and antiscorbutic[]. The succulent calyx, boiled in water, is used as a drink in the treatment of bilious attacks[].

The seeds are diuretic, laxative and tonic[]. They are used in the treatment of debility[].

The bitter root is aperitif, laxative and tonic[, ].

The plant is also reported to be antiseptic, aphrodisiac, astringent, cholagogue, demulcent, digestive, purgative and resolvent[]. It is used as a folk remedy in the treatment of abscesses, bilious conditions, cancer, cough, debility, dyspepsia, dysuria, fever, hangover, heart ailments, hypertension, neurosis, scurvy, and strangury[].
One report says that the plant has been shown to be of value in the treatment of arteriosclerosis and as an intestinal antiseptic, though it does not say which part of the plant is used[].

Simulated ingestion of the plant extract decreased the rate of absorption of alcohol, lessening the intensity of alcohol effects in chickens[].

Other Uses

A strong fibre obtained from the stem (called rosella hemp) is used for various household purposes including making sackcloth, twine and cord[, , , ]. The fibre, and sometimes the whole stem, is used in making paper[].

A yellow dye is obtained from the petals[]. It is used in medicines etc[].

The seed yields 20% oil[]. It is used in the soap and cosmetic industries and as an ingredient in paints[].

An extract of the flowers is used as an ingredient in commercial cosmetic preparations as a skin conditioner[].
A powder obtained from the flowers is used as an ingredient in commercial cosmetic preparations as an abrasive[].
The dried, crushed leaves and an extract of the leaves are both used as ingredients in commercial cosmetic preparations as an antioxidant and skin conditioner[, ].
An oil obtained from the seeds is used as an ingredient in commercial cosmetic preparations as an emollient[].

Propagation

Seed - sow early spring in a warm greenhouse. Germination is usually fairly rapid. Prick out the seedlings into individual pots when they are large enough to handle. If growing them as annuals, plant them out into their permanent positions in early summer and protect them with a frame or cloche until they are growing away well. If hoping to grow them as perennials, then it is better to grow them on in the greenhouse for their first year and to plant them out in early summer of the following year.
Cuttings of half-ripe wood, mid summer in a frame. Overwinter them in a warm greenhouse and plant out after the last expected frosts.