Stevia rebaudiana

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Family

Asteraceae

Synonyms

Eupatorium rebaudianum Bertoni

Traditional English Names

sweetleaf (USA), Sweet honey leaf (Aust.), sweet leaf, sugarleaf, Sweet herb of Paraguay, Honey leaf, Candy leaf or simply stevia, due to its sweet leaves. Stevia genus was discovered by the Spanish botanist and physicist Pedro Jaime Esteve (from whom the name Stevia). The species name, Rebaudiana, was attributed in honour of the chemist Rebaudi, who first studied plant sweetening substance.  

Common Greek names

Στέβια γλυκόφυλλη, γλυκοβότανο, μελόχορτο, καραμελόφυλλο.

Systematic Description

It is a perennial semi-shrub up to 30 cm in height . Leaves are sessile, 3-4 cm long, elongate-lanceolate or spatulate shape with blunt-tipped lamina, serrate margin from the middle to the tip and entire below. The upper surface of the leaf is slightly glandular pubescent. The stem is weak-pubescent at bottom and woody. The rhizome has slightly branching roots. Flowers are composite surrounded by an involucre of epicalyx. Capitula are in loose, irregular, sympodial cymes. The flowers are light purple, pentamerous. Fruit is a five-ribbed spindle-shaped achene.

Geographical Distribution

Stevia is a genus  native to subtropical and tropical regions from western North America to South America. S. America - Brazil, Paraguay.

subspecies

There aren’t listed any subspecies of Stevia rebaudiana.

Included taxa for stevia

Stevia rebaudiana is one of 154 members of the genus Stevia, however, there is no other Stevia species, which has exhibited the same intensity of sweetness as S. rebaudiana.

Part(s) of the plant that is (are) used for medical use, time of harvast and processing

Leaves

Traditional botanic and medicinal uses

Use as a sweetener: Stevia has a very sweet liquorice-like flavour. The leaves contain 'stevioside', a substance that is 300 times sweeter than sucrose. Other reports say that they contain 'estevin' a substance that, weight for weight, is 150 times sweeter than sugar. The dried leaves can be ground and used as a sweetener or soaked in water and the liquid used in making preserves. The powdered leaves are also added to herb teas. The leaves are sometimes chewed by those wishing to reduce their sugar intake. The leaves can also be cooked and eaten as a vegetable. Many commercial drink mixes and packaged sugar substitutes are sweetened with a derivative of stevia.

Phytochemical composition

Traditional use: For hundreds of years, indigenous peoples in Brazil and Paraguay have used the leaves of stevia as a sweetener. The Guarani Indians of Paraguay call it kaa jheι and have used it to sweeten their yerba mate tea for centuries. They have also used stevia to sweeten other teas and foods and have used it medicinally as a cardiotonic, for obesity, hypertension, and heartburn, and to help lower uric acid levels. In addition to being a sweetener, in Brazilian herbal medicine stevia is considered to be hypoglycemic, hypotensive, diuretic, cardiotonic, and tonic. The leaf is used for diabetes, obesity, cavities, hypertension, fatigue, depression, sweet cravings, and infections. The leaf is employed in traditional medical systems in Paraguay for the same purposes as in Brazil.

Phytochemical composition: Over 100 phytochemicals have been discovered in stevia since. The S. rebaudiana Bertoni contains a complex mixture of labdane diterpenes, triterpenes, stigmasterol, tannins, volatile oils, and eight diterpenenic glycosides: stevioside, steviobioside, dulcoside, and rebaudiosides A, B, C, D, and E. It is rich in terpenes and flavonoids. The constituents responsible for stevia's sweetness were documented in 1931, when eight novel plant chemicals called glycosides were discovered and named. Of these eight glycosides, one called stevioside is considered the sweetest - and has been tested to be approximately 300 times sweeter than sugar. Stevioside, comprising 6-18% of the stevia leaf, is also the most prevalent glycoside in the leaf. Other sweet constituents include steviolbioside, rebausiosides A-E, and dulcoside A.

Health benefits: It is probably the presence of the steviosides themselves that has produced dozens of empirical and semi-controlled reports of hypoglycemic action. According to studies, stevia is helpful for hypoglycemia and diabetes because it nourishes the pancreas and thereby helps to restore normal pancreatic function. The experimental research on the effects of stevia on blood sugar levels in human patients with either diabetes or hypoglycemia is sparse.

The ability of stevia to inhibit the growth and reproduction of bacteria and other infectious organisms is important in at least two respects. First, it may help explain why users of stevia-enhanced products report a lower incidence of colds and flus, and second, it has fostered the invention of a number of mouthwash and tooth paste products. Stevia has even been shown to lower the incidence of dental caries.

Since its introduction in China, stevia tea, made from either hot or cold water, is used as a low calorie, sweet-tasting tea, as an appetite stimulant, as a digestive aid, as an aid to weight management, and even for staying young.

One of the properties of a liquid extract of stevia that has not yet been investigated experimentally is its soothing action on skin. In folk medicine, it is placed directly in cuts and wounds, more rapid healing, without scarring, is observed.

Is the plant cultivated in local farms and in what extent

Cultivation details: It prefers a sandy soil, requiring a warm sunny position. It is a short day plant, growing up to 0.6 meters in the wild and flowering from January to March in the southern hemisphere. Flowering under short day conditions should occur 54-104 days following transplanting, depending on the daylength sensitivity of the cultivar. The natural climate is semi-humid subtropical with temperature extremes from 21 to 43 °C, averaging 24 °C. Stevia grows in areas with up to 1375 mm of rain a year. Plants are not very frost resistant.

Propagation: Seed - sow spring in a warm greenhouse and only just cover the seed. Make sure the compost does not dry out. Prick out the seedlings into individual pots and grow them on fast, planting them out after the last expected frosts. It could be worthwhile giving them some protection such as a cloche or cold frame for a few weeks after planting them out until they are growing away well.

Dangers

Generally regarded as safe. The  commonly reported short-term side effects of stevia are nausea or mild bloating after using the sweetener, dizziness, mild muscle pains after consumption or numbness. Avoid consumption be pregnant or breastfeeding women and people with ragweed allergies.

Bibliography