In Polygonum-type the micropylar dyad cell degenerated quickly, while the chalazal one finished meiosis II to form two unequal-sized megaspore.

• 韭型大孢子发生时，只进行减数第一次分裂，不发生减数第二次分裂，形成二分体，珠孔端二分体细胞退化，合点端二分体细胞发育为二倍体功能大孢子。