Endosperm

Endosperm is the starchy material found within a seed that feeds a baby plant (and us). This is where all those carbs are stored! The wheat used to make bread and the barley used to make beer are both endosperm. The popcorn and coconut we eat are also endosperm. ​

Drawing of seed by Kate Russell

When double-fertilization occurs, one male gamete becomes the baby plant and the other is used to create endosperm. This behavior is exclusive to flowering plants (angiosperm). Some plants, such as orchids, lack endosperm. (Maybe that’s why they’re so tricky to grow…)

Endosperm is mostly starch, but it also contains small amounts of oil and protein. Some seeds, such as sunflowers, contain a lot more oil than others. In some plants, like beans, the endosperm is completely absorbed as the new plant grows. In others, mostly grains and corn, the endosperm is stored. This storage occurs in the cotyledon. 

As you begin planting seeds in spring, you can improve germination rates by using seeds that look full and undamaged, providing plenty of moisture, and waiting until temperatures are consistently warm enough. (I know, it’s hard to wait, but it’s worth it.)

In some cases, scarification is needed to initiate germination and the absorption of endosperm. Scarification occurs naturally when freezing temperatures or fire occur. These conditions damage the seed coat, allowing moisture a way to enter. Many wild plants require scarification, including indigo, wild roses and licorice. You can scarify a seed by nicking it with a sharp blade.