抄録
Gross morphology and cell division frequency in the shoot apices of orchardgrass were investigated during the winter season. Increase in the length of apical dome was observed in early December but was not obvious in the other period until March (Fig. 4). Mean cell size constituting apical dome increased except the period between January 1 and February 1 (Fig. 5). Cell division frequency in the apical dome decreased since December and reached the lowest level at the middle of January, but dividing cells were found at this time. After the middle of January the frequency increased again (Fig. 6). Though gross morphological changes of the shoot apex was not obvious, increase in cell size and in cell division frequency after February 1 indicated the development of the shoot apex during the winter season.
