Question

Tigellum is-
A. Embryonic axis
B. Embryonic root
C. Embryonic shoot
D. Embryonic leaf

Answer 1

Hint: The Tigellum provides a site for the attachment of cotyledons and also divides the seeds into two halves in dicots.

Complete answer:
Tigellum of seed is known as the embryonal axis. It extends from plumule to the radicle. The cotyledons of seed i.e. the temporary food supply of seeds are attached to the curved embryonal axis at the cotyledonary node. The micropylar end of the embryonal axis is slender, rod-shaped, and little bulky and is also known as the ‘Hypocotyl'. It forms the radicle or the embryonic root while the other side of the embryonal axis that lies above the level of the seed cotyledon is known as the ‘Epicotyl’. The tip of epicotyl is called plumule and it gives rise to the shoot system. The plumule and radicle remain protected by the coleoptile and coleorhiza respectively.

So, the correct answer is ‘Embryonic axis’.

Note:
- In a variety of plants, the first leaves are formed out of plumule of the seeds, for example, the plumule may be present as a small pointed structure without any leaf initially as in sunflower. The protective pointed conical structure is known as Coleoptile.
- The primary root, or the radicle, is the first organ to appear when a seed germinates. It comes out of the micropylar end and grows downward into the soil, anchoring the seedling. - - It has a double protective covering. The inner layer is the root cap and the outer layer is known as Coleorhiza.
- A cotyledonary node refers to the origin of vascular strands from the embryonal axis.