Dr. Jeffrey M. Osborn
Dean of the School of Science and Professor of Biology
The College of New Jersey
Osborn, J. M. and T. N. Taylor. 1990. Morphological and ultrastructural studies of plant cuticular membranes.
I. Sun and shade leaves of
Quercus velutina(Fagaceae). Botanical Gazette 151: 465-476.
Sun and shade leaves of Quercus velutina Lam. were evaluated with respect to differences in gross anatomy,
morphology, and cuticle (cuticular membrane; CM) ultrastructure and micromorphology. Sun leaves are smaller,
with more deeply-lobed margins, have more stomata, thicker mesophylls, and thicker CMs when compared with shade
leaves. Cuticular membranes are thicker on both the adaxial and abaxial surfaces of sun leaves as a result of
deposition of more cuticular components and scaly epicuticular wax. Both the adaxial and abaxial epidermises
have the same basic fine structure in sun and shade leaves with respect to the outer periclinal cell wall and
overlying CM. The cell wall is lamellate and the CM is composed of a two-zoned, reticulate cuticular layer and
an amorphous cuticle proper. The outer periclinal wall and associated CM of the adaxial epidermis is thicker than
that of the abaxial epidermis with both epidermal layers thicker in sun leaves compared with shade leaves.
Difference in thickness of both epidermal layers, between sun and shade leaves, can be attributed to an increase
in the inner reticulate region of the CM of sun leaves. Cells of the abaxial epidermis have ultrastructurally
different CMs. Non-stomatal epidermal cells have a distinct amorphous cuticle proper while subsidiary cells have
reticulations that traverse most of the outer CM. Guard cells have radially aligned reticulations through the
entire outer CM, and therefore lack an amorphous cuticle proper. Moreover, an internal CM, which is only sparsely
reticulate, lines substomatal chambers. The internal CM of sun leaves is thicker and extends considerably deeper
into substomatal chambers.
cuticular membranes, cuticle, ultrastructure, sun leaves, shade leaves,
Quercus velutina, Fagaceae.