Solanaceae Family: Nightshade Characters and Examples
Solanaceae is the nightshade family of flowering plants. It includes potato, tomato, brinjal, chilli, tobacco, and belladonna. Its flowers are regular, five-petalled, and usually bell-shaped or funnel-shaped, and the fruit is a berry or a capsule.
This family is very important for food, medicine, and farming. Many daily vegetables come from it, but some members are poisonous, so correct identification is essential for safety and for plant breeding.
Key Concepts
Plants are mostly herbs or shrubs with alternate, simple leaves without stipules. Flowers are solitary or in cymes, bisexual, and actinomorphic, meaning they can be divided equally in many planes.
- Calyx: 5 sepals, united, persistent and often growing with the fruit in brinjal and tomato.
- Corolla: 5 petals, united, rotate or funnel-shaped.
- Androecium: 5 stamens attached to the corolla tube, called epipetalous.
- Gynoecium: Bicarpellary, syncarpous, superior ovary, bilocular with many ovules on swollen, oblique placenta.
- Fruit: Berry (tomato, brinjal) or capsule (tobacco, datura).
Floral formula: ⊕ ⚥ K(5) C(5) A5 G(2). The oblique ovary and swollen placenta are special identifying features.
How It Works
- The fused corolla forms a tube that protects the inner parts and guides insects.
- Stamens inserted on the corolla shed pollen onto visiting insects.
- After fertilisation, the bilocular ovary with many ovules grows into a berry or capsule.
- Seeds are endospermic, so the young seedling gets stored food during germination.
Worked Example
A tomato flower has 5 sepals, 5 petals, 5 stamens, and 2 carpels. If you collect 25 flowers, stamens total = 25 × 5 = 125. Each fruit from one flower may contain about 100 seeds. From 25 fruits, expected seeds = 25 × 100 = 2,500 seeds. The calculation shows why a few plants give enough seed for a large nursery.
Common Misconceptions
- Potato tuber is a fruit: Wrong. Potato tuber is a modified underground stem; the true fruit is a small berry.
- All Solanaceae are safe vegetables: Wrong. Belladonna and datura contain toxic alkaloids and are medicinal only in controlled doses.
- Ovary is straight like other families: Wrong. The carpels are obliquely placed, a key diagnostic character.
Real-World Applications
Potato, tomato, brinjal, and chillies are staple foods. Tobacco is a commercial leaf crop. Medicinal plants like Atropa belladonna give atropine, and Withania is used in Ayurveda. Ornamental petunia also belongs to this family and is grown in gardens worldwide.
Remember Solanaceae by its 5 united petals, 5 epipetalous stamens, bicarpellary oblique ovary, and berry or capsule fruit — a family of both food and medicine.