Stevia is member of Asteriaceae family which has 200 genus. Its height up to 1 m tall. It is a perennial herbaceous plant having extensive root system. Its leaves are sessile, 3–4 cm in length, elongate lanceolate or spatulate shaped with blunt-tipped lamina, serrate tip. The upper surface of the leaf is granular. Its stem is woody and weak at the bottom. The flowers are pentamerous, small and whitish. They are surrounded by an involucre of epicalyx. The capitula are loose, irregular and sympodial Cymes. The fruit is a five ridged spindle shaped achene.
Stevia will grow well on moist and well-drained soil. Plants under cultivation can reach up to 1 m or more in height. It is cultivated as a perennial shrubby plant in subtropical regions including some states of the USA. The plant is primarily originated from the northern regions of South America. It is also cultivated in China, Taiwan, Thailand, Korea, Brazil, and Malaysia. Stevia must be cultivated as an annual plant in high latitude areas, where longer days are favorable for leaf yield and stevioside contents. Seeds are contained in slender achene, about 3 mm long.
. Flower structure of stevia: Fig. Stevia flower structures.
Floral diagram of stevia: Fig: floral diagram of stevia.