Definitions [1]
Define the term inflorescence.
- A flower is a modified shoot wherein the shoot apical meristem changes to a floral meristem. Internodes do not elongate and the axis gets condensed.
- The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. When a shoot tip transforms into a flower, it is always solitary. The arrangement of flowers on the floral axis is termed inflorescence.
Key Points
Key Points: The Inflorescence
- Inflorescence = Arrangement of flowers on the floral axis.
- Racemose — Main axis continues to grow; flowers in acropetal order (bottom → top). Ex: Amaranthus, Mustard, Snapdragon.
- Cymose — Main axis terminates in a flower; limited growth; flowers in basipetal order (top → bottom). Ex: Calotropis, Cotton, Jasmine, Solanum.
- Flower = Modified shoot where the shoot apical meristem turns into a floral meristem; internodes do not elongate.
- Alternate phyllotaxy — One leaf per node, arranged alternately. Ex: China rose, Mustard.
- Opposite phyllotaxy — Two leaves per node, facing each other. Ex: Calotropis, Guava.
- Whorled phyllotaxy — More than two leaves per node, forming a circle. Ex: Alstonia.
Key Points: Fruits
- Formation - Fruits result from fertilisation; the wall of the ovary develops into the pericarp (fruit wall).
- Types of Fruits - Fruits are fleshy (guava, mango, orange) or dry (groundnut, mustard).
- True vs False Fruits - True fruits develop only from the ovary; False fruits develop from the thalamus + ovary (e.g., apple, strawberry, cashew).
- Parthenocarpic Fruits - Fruits that develop without fertilisation are called parthenocarpic (seedless) fruits (e.g., banana, grapes); they can be induced by growth hormones.
- Seed Viability - Viability of seeds varies widely; some lose viability in months, others survive for years or centuries (e.g., lupine seed germinated after 10,000 years; date palm seed viable after 2000 years).
