A morphological study of some members of the genus Pallavicinia . Fig. i. A. Male plant of Pallavicima (Mittenia) Zollingeri. x 2. B. Sterile plant of P. radiculosa, natural size; r, ventral branch. One of these secondary apical cells begins active growth and givesrise to the shoot which continues the sympodium. It grows horizontallyfor a time, but finally turns upward and develops into the next uprightgreen frond. Several segments are cut off from the apical cell beforea differentiation of the different tissues of the shoot is apparent. Finallythe midrib and lateral wings can be distinguished
A morphological study of some members of the genus Pallavicinia . Fig. i. A. Male plant of Pallavicima (Mittenia) Zollingeri. x 2. B. Sterile plant of P. radiculosa, natural size; r, ventral branch. One of these secondary apical cells begins active growth and givesrise to the shoot which continues the sympodium. It grows horizontallyfor a time, but finally turns upward and develops into the next uprightgreen frond. Several segments are cut off from the apical cell beforea differentiation of the different tissues of the shoot is apparent. Finallythe midrib and lateral wings can be distinguished, and in the former thecentral strand of elongated cells appears. Thus, at the base of the shoot, 8 GENUS PALLAVICINIA the conducting tissue is absent, and there is no connection between it andthat of the older shoot from which the branch has arisen (Fig. 2, B).. Fig. region !. Pallavicinia Z oiling a frond, showing rhizoids, and two ventral D. Part of the basal branches, longitudinal section of the base of a shoot passing through a young ventral branch. The conducting tissue of the main shoot and the branch are not ventral shoot (r) growing from the surface of the frond of an antheridiai plant. The remains of an antheridium may be seen upon the dorsal apical region of the shoot shown in C. x, the apical cell. E. Apical region of a ventral shoot. The other initial cells may never develop beyond cutting off a smallnumber of segments. These groups of cells may be recognized for along time on the surface of the shoot, near its base. Sometimes, how-ever, one or more of these cell-groups resume activity, and from them METHODS arise the slender, apparently adventitious branches which are often metwith upon the ventral side of the shoots. These slender cylindrical root-like branches may be only a few cells in
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
