“珠被”用英语怎么说？

某些植物的珠被和珠心细胞形成完全正常的胚.The cells of the integument and nucellus of some plants form perfectly normal embryos.大多数被子植物的胚珠有两层珠被, 而裸子植物通常只有一层.Most angiosperm ovules possess two integuments, while gymnosperms usually have only ...