An example of an endospermous seed is

Analyze the question: The question asks which seed is endospermous, which means a seed that keeps its endosperm (food store) when mature, instead of absorbing it into the cotyledons.

Explain the concept:

• Endospermous (albuminous) seeds: The endosperm stays as the main food store in the mature seed. The cotyledon is usually thin or small. Examples are maize, rice, wheat, castor oil seed, and coconut.
• Non-endospermous (exalbuminous) seeds: The endosperm is used up as the seed develops, and the food is stored in the cotyledons. Examples are beans, groundnut, cashew, cotton (mostly), and pea.

Solution:

• A. Bean seed: Food is stored in two fleshy cotyledons, so it is non-endospermous.
• B. Cashew nut: Food is stored in the cotyledons, so it is non-endospermous.
• C. Cotton seed: It is generally treated as having its food in the cotyledons. Some textbooks note a thin remnant of endosperm, but it is not the standard example of an endospermous seed.
• D. Maize grain: It has a large starchy endosperm that supplies food to the embryo during germination. The single cotyledon (the scutellum) only absorbs and passes on this food. This is the classic example of an endospermous monocot seed.

Tip: Remember that monocot cereals (maize, rice, wheat) are endospermous. For dicots, the usual examples in JAMB are non-endospermous seeds like beans, groundnut, and cashew. The exception to remember is castor oil seed, a dicot that is endospermous. Also, the maize "grain" is really a fruit (caryopsis) with the seed fused to the fruit wall.