Characteristics and economic importance of Solanaceae (potato family)

1. Diagnostic features

• Rarely trees, mostly herbs or shrubs.
• Leaves- simple, alternate in the vegetative parts and opposite in the floral region, ex-stipulate, petiolate or sub-sessile.
• Flowers- bisexual, actinomorphic and hypogynous.
• Stamens usually 5, polyandrous, epipetalous.
• Gynoecium- bi-carpellary, syncarpous with axile placentation, placenta is swollen, ovule numerous.
• Ovary obliquely placed.
• Fruit- a berry or a capsule.

2. Distribution

• Mostly grow in tropical, sub-tropical and temperate regions of the world.
• Central and South America are the main centers of the distribution.
• Several members of the family are grown all over the world for their great economic use.

3. Vegetative characters

a) Habit

• The plants are mostly herbs (Solanum, Lycopersicon).
• Some are shrubs (Datura, Cestrum) or rarely soft wooded trees (Solanum giganteum) or climbers (S. dulcamara).
• The genus Solanum shows a variety of habit ranging from herbs to trees.

b) Root

• branched tap root.

c) Stem

• Aerial, erect sometimes climbing (Solanum jasminoides), underground tuberous (S.tuberosum) herbaceous or woody.
• Branched, cylindrical, solid or hollow, hairy (Nicotiana, Petunia) or glabrous.

d) Leaves

• Mostly cauline or ramal, exstipulate, petiolate, sub-sessile or sessile.
• Alternate while opposite in floral regions, simple entire (Petunia), sometimes lobed or pinnately divided.
• Venation uni-costate reticulate.

4. Floral characters

i) Inflorescence

• Usually axillary or extra- axillary cyme (Solanum nigrum), helicoid cyme (S.tuberosum).
• Rarely the flowers are solitary axillary (Physalis) or terminal (Datura).

ii) Flowers

• Pedicellate or sub-sessile, bracteates or ebracteate, bisexual.
• Actinomorphic, complete, hypogynous, rarely zygomorphic (Scizanthus), pentamerous.
• Calyx
• Sepals 5, gamosepalous, 5-lobed, sometimes 4-6 lobed, persistent.
• Aestivation valvate or imbricate.

iii) Calyx

• Sepals 5, gamosepalous, 5-lobed, sometimes 4-6 lobed, persistent.
• Aestivation valvate or imbricate.

iv) Corolla

• Petals 5, gamopetalous, campanulate (Atropa), infundibuliform (Datura), rotate (Solanum), urceolate (Withania) or bilabiate and zygomorphic.
• Aestivation- usually valvate sometimes imbricate or twisted.

v) Androecium

• Stamens usually 5, rarely 4 in Browallia, polyandrous, epipetalous, alternating with corolla lobes.
• Stamens usually unequal or sometimes 4 and didynamous (Salpiglossis).
• When less than 5 the missing stamen is represented by staminode.
• Anthers bi-celled or one celled in Browallia, compactly arranged to form a cone around the gynoecium.
• Anthers dehisce by apical pore or longitudinal slits, introse.

vi) Gynoecium

• Bicarpellary, syncarpous, superior, ovary obliquely palced, bilocular.
• Placentation is axile, swollen placenta.
• Ovule numerous, sometimes carpels become tetra (Datura) or tri to penta locular (Nicandra) due to formation of false septa.
• Style single, stigma bi-lobed or capitate.

vii) Fruit

• Berry (Lycopersicon) or a capsule (Datura, Petunia).

viii) Seed

• Small, numerous, endospermic.
• Embryo curved or straight.

ix) General floral formula

Image source: braincart

Economic importance:

1. Vegetables

• Stem tubers of Solanum tuberosum (aalu) are used as vegetable.
• It also helps in production of starch, dextrin, several alcohols and some other industrial products.
• Fruits of Lycopersicon esculentum and S. melangena are eaten as vegetable.
• Capsicum annuum (Chilli) is used as spices and pickles.

2. Medicine

• Roots of Atropa belladonna yield a powerful alkaloid ‘atropine’ which is used in tinctures, plasters and relieving pain.
• It is also used for dilating pupils of eyes during eye treatment.
• The drug ‘stramonium’ used in asthma which is derived from Datura stramonium.
• Leaves of Nicotiana tabacum are used as sedative, antispasmodic and also in eradicating animals pests, such as lice.

3. Tobacco

• Dried leaves of tobacco are used in bidi, cigarettes, cigar, pipes, hukka as well as for chewing or snuffing.

4. Ornamental plants. e.g., Petunia hybrid, S. dulcamara, Cestrum diurnum, C. nocturnum, etc.

5. Withania somniferacan coagulate milk for making cheese.

References: 

i) https://byjus.com/biology/solanaceae-fabaceae-liliaceae/

ii) https://www.biologydiscussion.com/angiosperm/dicotyledons/solanaceae-characters-distribution-and-types/48409

Characteristics and economic importance of Solanaceae (potato family)