Morphology of Flowering Plants Notes: Class 11 Biology Chapter 5
Class 11 Biology Chapter 5 Morphology of Flowering Plants covers the external structure and modifications of the root, stem, leaf, inflorescence, flower, fruit, and seed in angiosperms.
Overview of Topics & Subtopics (Click to Jump)
1. The Root and the Stem
Short Note:
• Root system: tap root (dicots) or fibrous root (monocots); may show modifications for storage (carrot), support (prop roots in banyan), or respiration (pneumatophores in mangroves).
• Stem: ascending part of the axis bearing branches, leaves, flowers and fruits; may be modified for storage (potato tuber), support (tendrils), or protection (thorns).
2. The Leaf
Short Note:
• A leaf consists of leaf base, petiole and lamina; venation may be reticulate (dicots) or parallel (monocots).
• Leaves may be simple (single, undivided lamina) or compound (lamina divided into leaflets: pinnately or palmately compound).
3. The Flower, Fruit and Seed
Short Note:
• A typical flower has four whorls: Calyx (sepals), Corolla (petals), Androecium (stamens, male reproductive part), and Gynoecium (carpels/pistil, female reproductive part).
• A fruit develops from the ovary after fertilisation, consisting of a wall (pericarp) and seeds; may be fleshy or dry.
• A monocot seed typically has a single cotyledon (with endosperm often present), while a dicot seed has two cotyledons (often non-endospermic).
NCERT Textbook Exercise Questions
Define the term 'inflorescence'. Explain the basis for the different types of inflorescence in flowering plants.
Answer: Inflorescence refers to the arrangement of flowers on the floral axis (peduncle) of a plant. The basis for classification is whether the growth of the peduncle is limited or unlimited: in racemose inflorescence, the main axis continues to grow and produces flowers laterally (acropetal succession); in cymose inflorescence, the main axis terminates in a flower, limiting further growth, and lateral flowers develop in a basipetal manner.
Differentiate between: (a) racemose and cymose inflorescence, (b) fibrous root and adventitious root.
Answer: (a) In racemose inflorescence the main axis keeps growing indefinitely with flowers borne laterally in acropetal order; in cymose inflorescence the main axis ends in a flower, so growth is limited, with lateral flowers in basipetal order.
(b) Fibrous roots arise from the base of the stem, replacing the short-lived primary root, typically seen in monocots; adventitious roots arise from parts of the plant other than the radicle, such as stems or leaves.
Draw the structure of a typical dicot seed, and briefly describe the parts of a seed.
Answer: A typical dicot seed has a seed coat (testa and tegmen) enclosing the embryo, which consists of an embryonal axis, two cotyledons (often storing food, making the seed non-endospermic), a plumule (young shoot) and a radicle (young root).
Define the term 'placentation'. Explain the different types of placentation found in flowering plants.
Answer: Placentation is the arrangement of ovules within the ovary. Types include: marginal (ovules on the fused margin, e.g. pea), axile (ovules on central axis, e.g. china rose), parietal (ovules on the inner wall, e.g. mustard), free central (ovules on a central axis without septa, e.g. dianthus), and basal (a single ovule at the base, e.g. sunflower).
