prothallium E原叶体
prothallium development原叶体发育
prothallium-prothallia原叶体
N（名词） the small flat free-living gametophyte that bears the reproductive organs of ferns, horsetails, and club mosses. It is either a green disc on the soil surface or it is colourless and subterranean 原叶体 [botany]