The Root Apical Meristem of Osmunda regalis

Abstract

Roots of the Osmundaceae differ from most ferns in having more than one apical cell. The size of the apical initial group, which includes cells that are considered to be apical cells, varies directly with root diameter in Osmunda regalis L. Mitotic indices were 6.63% for apical cells, 7.45% for the entire apical group, 6.25% for distal derivatives, and 7.15% for developing cortical cells. Cytophotometric measurements of Fuelgen‐stained nuclei indicated no endopolyploidy in the populations of cells studied. These findings demonstrate that there is no quiescent center in the roots of O. regalis.

Chloroplast Genome Evolution in Early Diverged Leptosporangiate Ferns

“…Many researchers consider the Osmundales to be closely related to eusporangiate ferns ( Pryer et al, 2001 ; 2004 ; Schneider et al, 2004 ; Schuettpelz and Pryer, 2007 ; Wolf et al, 1995 ). Osmun-dales also have been considered as intermediate taxa between eusporangiate and leptosporangiate ferns based on their external appearance, and anatomical and meristem characteristics ( Cross, 1931a ; 1931b ; Freeberg and Gifford Jr, 1984 ; Gifford Jr, 1983 ). Using fossil records, Osmundaceae could be traced back to the Late Permian period, but the genus Osmunda was known from the Late Triassic period.…”

Evolution of root apical meristem structures in vascular plants: plasmodesmatal networks

“…The RAMs of very old and large Angiopteris and Osmunda plants reportedly have a group of apical cells instead of a single apical cell, (Freeberg and Gifford, ; Barlow, ). We did not observe rows of apical cells in such large RAMs.…”

“…With respect of RAM evolution in vascular plants, Boronin (from 1969, as cited by Barlow, ) proposed a hypothesis that the propensity to form centrally placed tetrahedral apical cells may be a primitive characteristic and that plural initial cells in seed plants evolved first through polyhedral apical cells (increase in cutting facets), followed over time by the development of a cluster of apical cells, as found in Osmunda and Angiopteris , phylogenetically basal groups of ferns (monilophytes). Actually, the RAMs of Angiopteris (Angiopteridaceae) and Osmunda (Osmundaceae) were once reported to have plural initial cells when old (Freeberg and Gifford, ) and were classified as the open type, similar to angiosperm RAMs (Clowes, ). However, our PD data clearly show that RAMs of both genera ( Osmunda and Angiopteris ) have an LPD (fern type), not an IPD (seed‐plant type) or intermediate type.…”

The Root Apical Meristem of Asplenium Bulbiferum: Structure and Development

“…Conard (1908) described apical organization for Dennstaedtia punctilobula and summarized the results ofresearch on fern root apical structure up to that date. The early investigators were impressed with the tetrahedral apical cell as the progenitor of all building units of fern roots, although one definite apical cell is not apparent, for example, in Osmunda (Freeberg and Gifford, 1984) and in the Marattiaceae (Bower, 1889). However, Schiiepp (1966) has presented an analysis of root apical structure in Angiopteris (Marattiaceae) in which he purports to demonstrate the presence of a cubical cell that is responsible for the initiation of the observed cell network.…”