Understanding the Cotyledon in Grass Seeds

The question asks about the specific name given to the cotyledon found in the seed of the grass family. The grass family, also known as Poaceae, includes important plants like wheat, rice, maize, and barley. Their seeds have a distinct structure compared to dicotyledonous seeds.

What is a Cotyledon?

A cotyledon is an embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed. They are crucial for providing nourishment to the developing seedling, either by storing food or by photosynthesizing after germination.

Seed Structure of Grasses (Monocots)

Seeds of the grass family are monocotyledonous, meaning they have only one cotyledon. This single cotyledon is highly specialized and is known by a specific name. The seed also consists of the embryo (which includes the plumule and radicle) and the endosperm, which stores food.

Analyzing the Options

Let's examine each option provided:

• (a) Coleoptile: The coleoptile is a protective sheath that covers the plumule (embryonic shoot) in monocotyledonous plants like grasses. It helps the shoot push through the soil during germination. It is not the cotyledon.
• (b) Coleorhiza: The coleorhiza is a protective sheath that covers the radicle (embryonic root) in monocotyledonous plants. It protects the root as it emerges from the seed. It is not the cotyledon.
• (c) Algal bloom: An algal bloom is a rapid increase in the population of algae in an aquatic system. This term is completely unrelated to seed structure or plant reproduction.
• (d) Scutellum: The scutellum is the single, shield-shaped cotyledon found in the seeds of grasses. Its primary function is to absorb processed food materials from the endosperm and transfer them to the developing embryo during germination. It is the specialized cotyledon in the grass family.

Identifying the Cotyledon in Grass Seeds

Based on the analysis of the seed structure of the grass family and the functions of the listed parts, the scutellum is the structure that serves as the cotyledon.

Summary

In the seed of the grass family (monocots), the cotyledon is a specialized structure called the scutellum. The coleoptile and coleorhiza are protective sheaths for the plumule and radicle, respectively, and algal bloom is an unrelated ecological phenomenon.

Revision Table: Grass Seed Structures

Additional Information: Seed Germination in Grasses

During germination in grass seeds, the radicle emerges first, protected by the coleorhiza. The coleorhiza is soon ruptured. The plumule then elongates and is protected by the coleoptile as it grows upwards through the soil. The scutellum remains within the seed, facilitating the transfer of stored food from the endosperm to the actively growing embryo until the seedling becomes self-sufficient through photosynthesis.