Abstract
As the cells of the archesporium multiply, the plastids flatten and become internally simplified, and no longer contain conspicuous grana. The plastids in the sporocyte round up with the onset of meiosis. The single plastid in each spore is highly simplified and nearly spherical. After the exine of the spore is elaborated, the plastid becomes polymorphic, forms one or more prolamellar bodies and begins to rebuild the grana-fretwork system. Typical chloroplasts are developed before the spores are shed.
During the early phases of development of the archesporium, its plastids fluoresce a brilliant red in blue light. This chlorophyll fluorescence dims by the time sporocytes are developed, and is virtually undetectable in the newly formed spores. No increase in chlorophyll fluorescence is noted until after the elaboration of the yellow-fluorescing exine. These observations indicate a shut-down in vegetative plastid activities during sporogenesis, and a return to the vegetative state before the spores are shed. The continuity of the plastids through sporogenesis is virtually certain.
