SOLANACEAE - the potato family

SOLANACEAE - the potato family

Systematic position

Class: Dicotyledonae

Sub-class: Gamopetalae

Series: Bicarpellatae

Order: Polemoniales

Family: Solanaceae

General characters

Distribution

Solanaceae includes about 90 genera and more than 2,800 species. The plants are widely distributed in tropical and subtropical regions. In India, this family is represented by 21 genera and 70 species.

Habit

Mostly annual herbs (eg. Solanum melongena), a few shrubs eg. Solanum torvum (Sundaikaai) and rarely trees (S. giganteum).

Root

A branched tap root system.

Stem

Aerial, erect, spinous eg. Solanum xanthocarpum (Kandangkathiri), herbaceous, woody, cylindrical, branched, hairy (eg. Petunia hybrida and Nicotiana alata). In S. tuberosum, the stem is modified into tuber.

Leaf

Petiolate, usually alternate, sometimes opposite, simple, entire (eg. Petunia hybrida), exstipulate and showing unicostate reticulate venation. In S. xanthocarpum, the midrib and veins are found with yellowish spines.

Inflorescence

Solitary, axillary cyme (eg. Datura stramonium) or extra axillary scorpioid cyme called rhipidium (fan shaped cyme) as in S. nigrum or helicoid cyme as in S. tuberosum or umbellate cyme as in Withania somnifera.

Flower

Bracteate (eg. Petunia hybrida) or ebracteate eg. S. nigrum (Manathakkaali), ebracteolate, pedicellate, dichlamydeous, pentamerous, complete, actinomorphic (eg. Datura stramonium) or Zygomorphic (eg. Schizanthus pinnatus), bisexual and hypogynous.

Calyx

Sepals 5, green, gamosepalous, tubular and showing valvate aestivation eg. Datura metal (Oomathai) or imbricate aestivation (eg. Petunia hybrida), bell shaped and persistent (S. melongena).

Corolla

Petals 5, gamopetalous, funnel shaped, rotate, tubular, usually plicate (folded like a fan blade) showing twisted or valvate or imbricate aestivation.

Androecium

Stamens 5, epipetalous, alternate with the petals, usually not equal in length and filaments are inserted in the middle or basal region of corolla tube and basifixed. Anthers dithecous, introrse, usually basifixed or dorsifixed, dehiscing longitudinally or through apical pores (eg. S. nigrum). In Schizanthus pinnatus, two stamens are fertile and three stamens are reduced to staminodes.

Gynoecium

Ovary superior, bicarpellary and syncarpous. Ovary bilocular, carpels obliquely placed and ovules on axile placentation. In Datura species, bilocule becomes tetralocular by the formation of false septa. Style simple and undivided. Stigma bifid or capitate.

Fruit

A berry or septicidal capsule. In Lycopersicon esculentum, the fruit is a berry and in species of Datura and Petunia, the fruit is a capsule.

Seed

Endospermous.