In monosporic and bisporic megasporogenesis: the megaspore(s) that would not participate in megagametogenesis. [source: TAIR:Leonore_Reiser]
Comment
If you are annotating to this structure for Zea mays or other grasses, please also add an annotation to the corresponding floret type. Choose the most specific term possible from: spikelet floret (PO:0009082), ear floret (PO:0006354), upper floret of pedicellate spikelet of ear (PO:0006350), upper floret of sessile spikelet of ear (PO:0006352).