TY - JOUR
T1 - Scanning electron microscope studies of cycad tracheids
AU - Schneider, E. L.
AU - Carlquist, S.
AU - Chemnick, J. G.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2007/11
Y1 - 2007/11
N2 - SEM studies of pit membranes of cycad tracheids revealed porosities in some, but not most of the tracheid pits examined. Porosities, where present, are mostly varied in size and density. Porosities do not extend through pit membranes and appear limited to the first-formed portion of the primary wall. Because of inconsistency in porosity presence within a secondary xylem sample, as well as between stems and roots of a species, and among species, interpretation is difficult. Earlier reports of perforations or perforation plates in cycads are not confirmed, and may be the result of oxidative effects of maceration fluids. Forms of helical sculpture on the inner surfaces of tracheids in Encephalartos and Zamia represent a phenomenon newly reported for cycads. Helical sculpturing on secondary xylem elements of other vascular plants is usually interpreted as a xeromorphic feature, and this interpretation may be valid for cycads as well.
AB - SEM studies of pit membranes of cycad tracheids revealed porosities in some, but not most of the tracheid pits examined. Porosities, where present, are mostly varied in size and density. Porosities do not extend through pit membranes and appear limited to the first-formed portion of the primary wall. Because of inconsistency in porosity presence within a secondary xylem sample, as well as between stems and roots of a species, and among species, interpretation is difficult. Earlier reports of perforations or perforation plates in cycads are not confirmed, and may be the result of oxidative effects of maceration fluids. Forms of helical sculpture on the inner surfaces of tracheids in Encephalartos and Zamia represent a phenomenon newly reported for cycads. Helical sculpturing on secondary xylem elements of other vascular plants is usually interpreted as a xeromorphic feature, and this interpretation may be valid for cycads as well.
KW - Gymnosperms
KW - Helical sculpture in tracheids
KW - Scanning electron microscopy
KW - Tracheary elements
KW - Xylem evolution
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U2 - 10.1016/j.sajb.2007.04.060
DO - 10.1016/j.sajb.2007.04.060
M3 - Article
AN - SCOPUS:35348816116
SN - 0254-6299
VL - 73
SP - 512
EP - 517
JO - South African Journal of Botany
JF - South African Journal of Botany
IS - 4
ER -