INTERCALARY MERISTEMATIC ACTIVITY IN THE SPOROPHYTE OF FUNARIA (MUSCI).

Marking procedures were combined with anatomical techniques to establish that in Funaria (1) the apical region does not act as an apical meristem contributing to seta growth, and (2) the subapical region contains an intercalary meristem the derivatives of which account for the elongation of the seta. In sporophytes that are 8 mm long there is a distinctive difference in the pattern of cell division in the apical and subapical regions. Large, undivided endothecial cells exist in the apical region, and a central strand of elongated cells occupies the analogous position in the subapical region. The apical region is earmarked to form the operculum and spore sac and part of the apophysis. There is an ontogenetic continuity between the seta and the lower portion of the apophysis, but the uppermost cells of the subapical region do not contribute to seta formation. Instead, these cells and those at the base of the apical region form a transitional zone between apical and subapical influences, and they account for most of the stomates that develop on the apophysis. © 1975 Botanical Society of America.