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How does endosperm provide food for a developing plant embryo?

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Bumblebee on teasel — plant reproductive system A large bumblebee (*Bombus* species) pollinating a teasel flower head (*Dipsacus* species).

In angiosperms, the endosperm serves as a vital nutrient-rich tissue that nourishes the developing embryo until it becomes self-supporting through photosynthesis.12

The endosperm is formed during double fertilization, when a sperm nucleus fuses with two polar nuclei to create a triploid tissue. This tissue stores essential reserves, including starch, sugars, fats, and proteins.13

Because these reserves are often stored in insoluble forms, the seedling must mobilize them during germination. This process typically involves the cotyledons, which act as absorbing organs to break down and translocate these nutrients to the developing radicle and epicotyl. For example, in many grasses, the cotyledon is modified into an enzyme-secreting structure called a scutellum that sits between the embryo and the endosperm to facilitate the withdrawal of these stored materials.23