Helobial Type - Endosperm
This type of endosperm is intermediate between the nuclear and the cellular types. The division of the primary endosperm nucleus is followed by the formation of transverse wall that divides the embryo sac into two chambers-the micropylar and the chalazal. The micropylar chamber is larger and undergoes active nuclear divisions to form several free nuclei. The chalazal chamber is smaller and its nucleus may not divide or may undergo only a few divisions.
Later on wall formation normally takes places only in the micropylar chamber which forms the main endosperm. The chalazal chamber eventually becomes crushed and its nuclei disintegrated. According to Swamy and Parameshwaran, the formation of true Helobial endosperm is confined only to the monocotyledonous families. If it occurs in dicotyledonous families, it is only a modification of the cellular or nuclear type of endosperm. However, typical helobial type of endosperm has been observed in dicotyledonous families, such as Santalaceae and Saxifragaceae.