Structural aspects of female sterility in Citrus limon

In Citrus limon structural aspects of female sterility have been investigated. The results obtained are compared with the development of the female fertile flowers. Pistils of female sterile flowers appear defective in all stages of development. In pistils of female fertile flowers only a few ovules reach a fertilizable stage, most ovules do not form a mature embryo sac, but the development of integuments and nucellus seems normal. In non-functional pistils a possible blocking of further stigma and style development is related to the presence or absence of receptive embryo sacs in the ovule.