Biology · Ch 1 — Sexual Reproduction in Flowering Plants
Endosperm
Endosperm
The endosperm is the nutritive tissue that supports the developing embryo. Its development actually begins before the embryo starts to form. Why? Because the embryo needs a ready supply of food from the very start of its growth.
The primary endosperm cell (PEC) — formed after triple fusion — divides repeatedly to build up a mass of triploid tissue. The cells of this tissue are packed with reserve food materials (like starch, oils, and proteins) that nourish the growing embryo.
How the endosperm develops
In the most common pattern, the primary endosperm nucleus (PEN) undergoes several rounds of nuclear division without forming cell walls. This stage is called free-nuclear endosperm. The number of free nuclei produced before walls appear varies greatly from species to species.
After enough free nuclei have formed, cell walls finally develop around them, and the endosperm becomes cellular.
The coconut water you drink from a tender coconut is actually free-nuclear endosperm — it contains thousands of free nuclei suspended in liquid. The white kernel (the solid part you eat) is the cellular endosperm that forms later.
What happens to the endosperm in the mature seed?
The fate of the endosperm differs between plants:
- Consumed before seed maturation — In many plants like pea, groundnut, and beans, the developing embryo uses up all the endosperm food. By the time the seed is mature, no endosperm remains; the food has been transferred to the cotyledons. …