COMPARATIVE ANATOMY OF THE PETIOLE IN SOLANUM SPECIES SECTION GEMINATA

Abstract

The Geminata Section of the genus Solanum
is integrated by 126 species, from which 35
are represented in Venezuela. These are very
homogeneous regarding its morphology
andgeneral growth habit with simpodial
branching. In the searching of other features
that allow their identification and/or separation, a study of petiole anatomy considering
micromorphoanatomics characters that can
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Núm. 34: 157-170 Agosto 2012
conform a taxonomic criterion for delimitation at specific level. For this first article, 18
species were considered using fresh and herborized material from MER, MY and VEN.
Petiole transverse sections from adult leaves
were hand made, stained and mounted in
semipermanent slides for observationunder
a compound microscope. The dimension of
transversal and longitudinal axis of sections,
the trichome type and density, stomata type
and density, number of epidermal layers and
cell shape, bundle sheath form, dimensions
and wings length were registered. The most
contrasting petioles micromorphological
features between the studied species were
the quantitative referred to trichomes number with high densities for S. chlamydogynum, S. microleprodes and S. oblongifolium
with 36 trichomes.mm-2 and petiole wing
length to 1700 μm in S. obovalifolium.
The rest quantitative characters studied
and all the qualitative features have a lack
of significanceto relate these species. In
addition, the presence of collenchyma only
in S. nudum and S. obovalifolium petiole,
as well as abundant sandy crystals only six
species would differentiate them from the
rest of those considered.