Question

Describe the structure and organisation of stem apex.

Answer 1

Shoot apex is the terminal part of the shoot with leaf primordium.

Various theories are given to explain its structure and organization but the most accepted theory is corpus tunica theory given by Schmidt in 1924.

Structure and organization of shoot apex-

1. It is convex in shape or slightly elongated at the base.
2. It is divided into four regions-tunica, corpus, flank meristem, and rib meristem.
3. Tunica is divided into two single layers outer and inner tunica that divide from anticlinal division and forms epidermis.
4. Corpus layer is 3 to 5 layer thick and divides at any plane to provide volume growth to the plant.
5. Cells of flank meristem are small, narrow and radially elongated.
6. Rib meristem is present below corpus.
7. Leaf is generally grown by periclinal division in an inner corpus.