Solanaceae

The Solanaceae family is also known as the Potato family or nightshade family. Solanaceae comes under order solanales. It is the family of flowering plants that range from annual and perennial herbs to shrubs, epiphytes, and trees and also includes many agriculture crops, medicinal plants, spices, ornamentals, etc. The term Solanaceae is derived from the genus Solanum. The family consists of 2000 species belonging to 90 genera. 71 species of 21 genera belong to India. The family is widely distributed in different parts of the world. Plants are terrestrial and are found in both temperate and tropical areas around the globe. They also grow in the wild in shady places. 

Vegetative Characteristics 

Habit and habitat

• The habit of the members of the Solanaceae family is variable. They are mostly herbs and shrubs. Some are small trees also.
• Solanum nigrum is a short-lived annual herb. Datura is a large annual plant.
• Most of the members of this family are mesophytes, and some are xerophytes (Eg. Solanum surattense)

Root

• The members of the Solanaceae family possess a branched tap root system.
• In some of the members, adventitious roots are also present.

Stem

• The stem is erect, aerial, and mostly herbaceous.
• In some species, the stem is also seen twinning, creeping, or climbing (Eg. Solanum jasminoides).
• In solanum, the tuberosum stem is an underground tuber.
• Bicollateral types of vascular bundles are present (phloem is present on the other side of the xylem separated by cambium).

Leaf

• The leaves are generally simple, lobed, and exstipulate.
• Leaves are herbaceous, leathery, or transformed into spines.
• They are generally petiolate or subsessile, rarely sessile.
• They show alternate or terminal phyllotaxy in vegetative regions.
• Venation is reticulate and lacks a basal meristem.

Floral Characteristics 

Inflorescence

• It is generally of cymose-solitary
• Rarely racemose- terminal or axillary.

Flower

• The flowers appear to be solitary or axillary, sometimes clustered.
• The flower is complete, bisexual (hermaphrodite), although some are monoecious andromonoecious.
• Pedicellate, regular, pentamerous, with no bracts or bracteoles.
• Usually actinomorphic or sometimes zygomorphic (Eg. Salpiglossis, Schizanthus)
• Hypogynous and complete flower.

Calyx

• The calyx consists of five sepals.
• All the sepals are fused (gamosepalous).
• The aestivation is valvate or imbricate.
• They are green or coloured, hairy, inferior.

Corolla 

• The corolla consists of five petals.
• All the petals are fused (gamopetalous).
• The aestivation is valvate or twisted.
• Sometimes the corolla is strongly zygomorphic and may become bi-lipped.

Androecium

• The stamens are five in number and are usually unequal in height.
• They are epipetalous on the corolla tube and alternate with the lobes.
• There are only four stamen or two fertile stamens in some zygomorphic forms, and the remaining are staminodes.
• They are alternipetalous; filaments are inserted deep in the corolla tube.

Gynoecium

• The gynoecium consists of the bicarpellary and syncarpous ovary.
• The ovary is usually superior, bilocular, occasionally unilocular.
• The ovary is tetralocular in Datura due to the development of a false septum.
• Placentation is axile on which numerous ovules are arranged. 
• The placenta is usually swollen.
• The style is linear, terminal and stigma is capitate or shortly lobed.
• The stigma is bilobed and capitated in style.

Fruit

• The fruit is mostly seen in the form of berry (enclosed within calyx) or in the form of a capsule (dehisces by valves).

Seed

• The seeds are many and are endospermic (albuminous) with curved or straight embryos.
• The seeds are mostly dicotyledonous.

Pollination

• Flowers are usually protandrous and possess an entomophilous type of pollination (pollination through insects)
• Some of the species are protogynous.
• In a few species, self-pollination is seen.

Distribution of Solanaceae

The family includes 2000 species belonging to 90 genera. 71 species of 21 genera belong to India. It is present around both tropical and temperate areas of the world. The family has a worldwide distribution in all the continents except Antarctica. Most of the Solanaceae family species are found in South America and Central America. In India, they are mainly found in the Himalayan regions, southern and eastern India.

Economic importance of Solanaceae

The family Solanaceae is of great economic importance. They contribute several important food, drug, and ornamental plants to humans.

• Many members such as Potato (Solanum tuberosum), Tomatoes (Lycopersicon esculentum), Tobacco (Nicotiana tabacum), Chilly (Capsicum annum), Brinjal (Solanum melongena) are used as vegetables. 
• Tomato is used in the manufacture of sauce and ketchup.
• Chilly (Capsicum annum) is dried and used as a source of chilli powder which is the main spice in India.
• Atropa belladonna (Belladonna) contains alkaloid Atropine which is the basis for the drug belladonna used in tinctures and plasters.
• Tobacco is obtained from leaves of Nicotiana tabacum and is used in the manufacture of various narcotic products such as cigars, bidi, chewing, jarda, etc.

Significant plants

• Potato (Solanum tuberosum)
• Tomatoes (Lycopersicon esculentum)
• Tobacco (Nicotiana tabacum)
• Chilli (Capsicum annum)
• Raspberry (Physalis peruviana)
• Brinjal (Solanum melongena)

Conclusion

The family Solanaceae is widely distributed in different parts of the world except for Antarctica. The plants are terrestrial and grow in both temperate and tropical regions. They are mainly annual herbs, shrubs, and rare trees. They possess a tap root system. The stem is erect and weak, maybe aerial or underground. The leaves are alternate, simple or pinnately compound, exstipulate, and possess reticulate venation. The inflorescence is usually cymose. The flowers appear to be solitary and axillary. The calyx consists of five sepals and is gamosepalous. The corolla consists of five petals and is gamopetalous. The androecium consists of five Stemmons and is epipetalous. The gynoecium is syncarpous, bicarpellary, and superior ovary with axile placentation.