1.Introduction Angiosperms are the most important group of plants in the current earth ecosystem.However,little is known about the origin of angiosperms,which has been a headache for many botanists.The core question in the origin of angiosperms is the homology of carpels.Formerly,Arber EAN and Parkin J(1907)speculated that the carpels in angiosperms were derived from the former megasporophylls bearing ovules along their margins.
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