MORPHOLOGY OF FLOWERING PLANTS
NCERT Masterclass & NEET Biology Study Module
1. The Root and its Modifications
The root is the underground part of the plant developed from the radicle of the embryo.
- Tap Root System: Primary root grows directly from the radicle. Found in Dicotyledonous plants (e.g., Mustard).
- Fibrous Root System: Primary root is short-lived; replaced by a large number of roots originating from the base of the stem. Found in Monocotyledonous plants (e.g., Wheat).
- Adventitious Roots: Arise from parts of the plant other than the radicle (e.g., Grass, Monstera, Banyan tree).
- Storage: Tap roots of Carrot, Turnip, and Adventitious roots of Sweet potato.
- Support: Prop roots (hanging from branches of Banyan tree) and Stilt roots (coming from lower nodes of stem in Maize and Sugarcane).
- Respiration: Pneumatophores (grow vertically upwards to get oxygen for respiration) found in Rhizophora growing in swampy areas.
2. The Stem and its Modifications
Developed from the plumule of the embryo. It bears nodes and internodes.
- Underground modifications (Storage/Perennation): Potato (tuber), Ginger (rhizome), Turmeric, Zaminkand, Colocasia.
- Stem Tendrils: Develop from axillary buds, help plants climb (e.g., Gourds - cucumber, pumpkins, watermelon; and Grapevines).
- Thorns: Axillary buds modified into woody, straight, pointed thorns for protection (e.g., Citrus, Bougainvillea).
- Phylloclade: Flattened (Opuntia) or fleshy cylindrical (Euphorbia) photosynthetic stems containing chlorophyll.
3. The Leaf and Inflorescence
The leaf is a lateral, generally flattened structure borne on the stem. Originates from shoot apical meristems and is arranged in an acropetal order.
- Venation: Reticulate (network, mostly in dicots) and Parallel (mostly in monocots).
- Phyllotaxy: Pattern of arrangement of leaves on the stem.
- Alternate: Single leaf at each node (China rose, Mustard, Sunflower).
- Opposite: A pair of leaves at each node (Calotropis, Guava).
- Whorled: More than two leaves at a node (Alstonia).
Inflorescence: Arrangement of flowers on the floral axis. Racemose (main axis continues to grow, flowers laterally in acropetal succession) and Cymose (main axis terminates in a flower, limited growth, basipetal order).
4. The Flower and its Parts
A flower is a modified shoot meant for reproduction. Contains four whorls: Calyx, Corolla, Androecium, and Gynoecium.
- Aestivation: Arrangement of sepals/petals. Valvate (Calotropis), Twisted (China rose, Lady's finger, Cotton), Imbricate (Cassia, Gulmohur), Vexillary/Papilionaceous (Pea, Bean).
- Androecium (Stamens): Can be united into one bunch (monoadelphous - China rose), two bunches (diadelphous - Pea), or more than two (polyadelphous - Citrus).
- Placentation: Arrangement of ovules within the ovary.
5. The Fruit and The Seed
The fruit is a characteristic feature of flowering plants. It is a mature/ripened ovary. If formed without fertilization, it is a parthenocarpic fruit.
In Mango and Coconut, the fruit is known as a Drupe. They develop from monocarpellary superior ovaries and are one-seeded. The mesocarp of mango is fleshy/edible, while in coconut, it is fibrous.
6. Description of Family: Solanaceae
Commonly called the 'potato family'. It is widely distributed in tropics, subtropics and even temperate zones.
- Leaves: Alternate, simple, rarely pinnately compound, exstipulate, reticulate venation.
- Inflorescence: Solitary, axillary or cymose as in Solanum.
- Flower: Bisexual, actinomorphic.
- Calyx/Corolla: Sepals/Petals five, united, valvate aestivation.
- Androecium: Stamens five, epipetalous.
- Gynoecium: Bicarpellary, obligately placed, syncarpous, ovary superior, bilocular, placenta swollen with many ovules. Axile placentation.
- Floral Formula: $\oplus \text{ } \text{\female} \text{ } K_{(5)} C_{(5)} A_5 \underline{G}_{(2)}$
🚀 NEET MORPHOLOGY MEGA QUIZ (100 MCQ)
Solve the 5 parts below to master Roots, Stems, Leaves, Flowers, Fruits, and Families.
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