Anatomy of Flowering Plants — BIOLOGY STD 11 Science — Question

Trichomes: They are unicellular or multicellular outgrowths which are strictly epidermal in origin. Trichomes are of two kinds, hair and scales. Hairs are elongated structures and can be unicellular or multicellular. Scales are multicellular flattened structures.

1. Root hairs: They are unicellular tubular structures found in epiblema of root in a special area called root hair zone. Root hairs are enlargement of epiblema cells. They have vacuolated protoplasm and they are ephemeral. Nucleus occurs towards the apical part of the hair. They take part in absorption of water and mineral salts. They hold soil particles and play an important role in anchoring the plants.
2. Aerial hairs: They are unicellular or multicellular appendages which are covered by a layer of cuticle. They enclose stationary air and protect the plant organs against sudden changes of temperature and high rate of transpiration.

3. Stinging hairs: They are hollow hairs that contain siliceous tips and enclose poison. They protect the plant from herbivores.
4. Glandular hairs: Most of the glandular trichomes produce essential oils. They provide aroma to the plants. Temperature and high rate of transpiration.
5. Stinging hairs: They are hollow hairs that contain siliceous tips and enclose poison. They protect the plant from herbivores.
6. Glandular hairs: Most of the glandular trichomes produce essential oils. They provide aroma to the plants.

Emergences : They are multicellular epidermal outgrowths which also contain some inner tissues prickles are an example of emergences. They are sharp and stiff outgrowth. They do not have vascular supply. They protect the plant from excessive transpiration, grazing animals and in some cases they help in climbing.