Ultrastructural observations on programmed cell death of nucellus in Pennisetum squamulatum demonstrate that the chromatin of the nucleus of the cell in apoptosis shows a condensation process and that the nuclear envelope becomes swollen by the outer membrane heaving. The inner membrane of nuclear envelope develops some protrusions into the swollen space. The endoplasmic reticulum cisternae dilate. Mitochondria are found to lose cristae.