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How does double fertilization provide food for a developing Alismatales embryo?

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Flowering rush — Alismatales Showy and delicate flowers of the flowering rush (*Butomus umbellatus*).

In the plant order Alismatales, double fertilization is a critical reproductive process that ensures the developing embryo has a dedicated food source. During this process, one sperm nucleus fuses with the egg to form a diploid zygote, while a second sperm nucleus fuses with the two polar nuclei to create a triploid endosperm nucleus.21

This endosperm nucleus undergoes mitotic divisions to form the endosperm, a specialized nutrient-rich tissue that serves as a food-storage reservoir. In the Alismatales, this tissue typically develops according to the helobial pattern, where a cell wall forms between the first two nuclei, leading to a combination of cellular and nuclear development. As the embryo grows, it utilizes the stored materials within the endosperm—such as starch, sugars, fats, and proteins—to support its development and subsequent germination.21