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COMPARATIVE ONTOGENETIC STUDIES IN YOUNG SPOROPHYTES OF TREE FERNS. I. A PRIMITIVE AND AN ADVANCED TAXON
Author(s) -
Lucansky Terry W.,
White Richard A.
Publication year - 1976
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1976.tb11835.x
Subject(s) - biology , botany , sporophyte , fern , phyllotaxis , apical cell , frond , meristem , xylem , petiole (insect anatomy) , ontogeny , taxon , shoot , genus , genetics , cell
Ontogenetic studies of young sporophytes were undertaken to determine anatomical and morphological differences between a primitive (Lophosoria quadripinnata) and an advanced ( Sphaeropteris elongata) tree fern. In both species the first leaf is simple, fanshaped, and possesses dichotomous venation. Later‐formed leaves exhibit either a pinnate or bipinnate pattern of laminar dissection. As the sporophyte matures, the stelar pattern changes from a protostele to an amphiphloic siphonostele, and finally to a dictyostele in Sphaeropteris. Medullation of the protostele occurs either prior to or after the formation of the first leaf trace in both species. Differentiation of xylem in the shoot is acropetal and the appearance of mature protoxylem occurs closer to the apical meristem in Sphaeropteris. The nodal pattern varies within each species with a no gap 1‐trace pattern characteristic for the first two or three leaves, depending upon the taxon. In Lophosoria subsequent leaves possess a unilacunar 1‐trace nodal pattern, whereas a complete nodal series (1 gap 1‐trace to 1 gap 6‐trace) occurs in Sphaeropteris. Fusiform leaf gaps are noted in both species. The shoot apical meristem is dominated by a single apical cell, with an organized apical cell first found in P 2 . Stem, root, and petiole anatomy are discussed.