Structural Organisation in Animals and Plants - Morphology of Flowering Plants (Root, Stem, Leaf, Inflorescence, Flower, Fruit, Seed)

Root System: Developed from the radicle. Includes Tap root (primary and secondary branches, e.g., Mustard) and Adventitious roots (arising from parts other than the radicle, e.g., Banyan). Regions include: Root cap $\rightarrow$ Region of Meristematic activity $\rightarrow$ Region of Elongation $\rightarrow$ Region of Maturation (with root hairs).

Stem: Developed from the plumule. Characterized by the presence of nodes (where leaves are born) and internodes. Modifications include Underground (storage, e.g., $Solanum \text{ tuberosum}$), Sub-aerial (vegetative propagation), and Aerial (tendrils, thorns).

Leaf: Originates from shoot apical meristems. Parts: Leaf base, Petiole, and Lamina. Venation: Reticulate (network, e.g., Dicots) and Parallel (veins run parallel, e.g., Monocots). Phyllotaxy: Arrangement of leaves on stem—Alternate, Opposite, or Whorled.

Inflorescence: Arrangement of flowers on the floral axis (peduncle). Two types: Racemose (main axis continues to grow, flowers in acropetal succession) and Cymose (main axis terminates in a flower, flowers in basipetal succession).

Flower: The reproductive unit. Parts: Calyx ($K$), Corolla ($C$), Androecium ($A$), and Gynoecium ($G$). Symmetry: Actinomorphic (radial, $\oplus$) and Zygomorphic (bilateral, $\%$).

Ovary Position: Hypogynous (Superior ovary $\underline{G}$), Perigynous (Half-inferior ovary), and Epigynous (Inferior ovary $\overline{G}$).

Placentation: Arrangement of ovules within the ovary. Types: Marginal (Pea), Axile (China rose), Parietal (Mustard), Free central (Primrose), and Basal (Sunflower).

Fruit and Seed: Fruit is a ripened ovary. In Monocots (e.g., Maize), the seed coat is fused with the fruit wall and contains a single large cotyledon called the Scutellum. Dicots (e.g., Pea) have two cotyledons and a non-endospermic nature in many cases.