Apomixis inCortaderia jubata(Gramineae)

Abstract

Cortaderia jubata shows both somatic apospory and non-pseudogamy, as embryos are produced in sacs derived from nucellar cells and are well developed by the time the inflorescence emerges. No pollen is produced in the anth~rs and the megaspore mother cell degenerates early. C. rudiuscula follows a similar pattern. As all other grasses that are non-pseudogamous show gonial apospory (diplospory), these species of Cortaderia would appear to be unique in their mechanism of apomixis. Usually one synergid is present in each embryo sac in C. jubata, and typically this develops a massive haustorium extending through and beyond the micropyle. Wall ingrowths of transfer-cell type occur abundantly in the haustorium and also cover the outer walls of the antipodats and central ceU, being especially numerous near the synergid and undivided egg.