Double fertilization The fusion of one pollen nucleus with the egg to form the zygote and of the other pollen nucleus with a polar nucleus to form the triploid endosperm nucleus.

• 双受精：指花粉粒中的一个精子与胚珠中的卵细胞结合形成受精卵，另一个精核与极核结合形成三倍体的胚乳核。