A Natomoical Studies of Oil Bearing Species of Compositae: Vernoia Galainensis (Cass.)Less.and Guizotia Abyddinica (L’f)Cass’
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Date
1988-06
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Addis Ababa University
Abstract
Anatolnical features of stein internodes and the leaves
of Vernonia galamensis (Cass) Less. and Guizotia abyssinica
(L.:f.) Casso have been studied. Most of the anatomical
characters of the t,ro species are similar and hence are
described together; the stems of both species possess
uniseriate epidermic bearing uniseriate multicellular nonglandular
hairs; phloem fibers develop in a discrete manner
and do not form 0. continuous cylinder around the stern. At
the mid rib region, mature leaves of both species contain
three sets of vascular bundles. The thickening on the lateral
vessel lfalls of both species is annular at an earlier ontogenetic
stage, but scalariform and pitted vessel elements lfith
simple perforation plates lfere observed at later stages of
development.
Vessel dimensions and aggregation of vessels of both
speciesj however, sholfed definite correlation lfith the
habitat climatic oondition that is prevalent in the natural
area of distribution of the tlfO species. In this respect
Q. abyssinica is characterized by lfider and longer vessel
elements as compered tv y.. galamensis "'hieh has shorter,
narrower and denser vessel elements. Tangential longitudinal
section through the vascular bundle of y. galamansis
showed considerable development of vascular rays. Both
uniserinte as well as lnultiseriate rays are observed. Collenchyma develops in the stems of both species
next to the epidormis. In Y... galamensis there are 3-ll
cell layers Vlhilc in Q. abyssinica there are only 2 layers
of collenchyma. Considerable development of aerenchyma in
the stem of Q. abyssinica is observed indicating its usually
moist natural habitat Vlhich probably induces development of
lacunae. The pith of Q. abyssinica starts to disint"egrate at
earlier stage during the development of the plant. Ecological
significance of hollo;; pith as it occurs in Q. abyssinica
is discussed along with other anatomical characters.
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Biology