Differentiation of dicyclic stele in Pteridium aquilinum (Dennstaedtiaceae).

摘要

The differentiation of Pteridium aquilinum dicyclic stele was studied. The apical meristem had a typical zonal structure and was protected by a ridge in which vascular tissues were differentiated. The identical orientation of vascular bands in the ridge and petiole in the shape of an omega confirmed that the ridge was the embryonic leaf. The outer ring of the rhizome vascular system was formed by bundles of leaf traces. Two central meristeles separated by two gaps corresponded to the dictyostele. In the rhizome apex, the leaf traces contacted both the meristeles of the dictyostele and the leaf trace of the older leaf. In the mature rhizome these contacts between the outer ring of the meristeles led to a variation in the number of meristeles and parenchymatous gaps between them, which were confined to the nodal zone. As a result, perforations appeared. Meristeles of the outer and inner rings came into contact close to the nodal zone.