Morphological and Chromosome Cytotaxonomical Studies of Ledebouria Roth and Drimiopsis Lindl. and Paxt. (Hyacinthaceae) in Ethiopia
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Date
2006-06
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Addis Ababa University
Abstract
The main aim of this investigation was to re-visit the taxonomy and chromosome cytology
of the genera Ledebouria and Drimiopsis (Hyacinthaceae) in Ethiopia and to improve
the descriptions and classification of the species under the two genera. In the study,
morphological data from both vegetative and floral characteristic features were
generated and SPSS version 11 was used for data analysis. NTSYS version 2.1 was also
used to construct dendrograms based on the overall qualitative and quantitative data.
Chromosome cytological features were also studied and chromosomes size and arm ratio
measurements were made on enlarged photomicrographs using a computer application
micromeasure software version 3:2. The computed cluster analysis based on
morphological data revealed that the two genera are distinict morphological groups and
almost all the specimens examined for each species of the two genera form independent.
But, L. urceolta is closely related to L. revoluta and the cluster analysis does not support
recognizing L. urceolata as a separate taxon. Most of the herbarium materials identified
as D. botryoides were also found to be very different from the description of the taxon in
the Flora (FEE) in both floral and vegetative characteristic features. This calls for
further investigations to determine the taxonomic identity of the materials. Chromosome
counts for five and two different cytotypes of L. revoluta and L. cordifolia are also
presented, respectively. Out of these, five of them represent new chromosome number
report: L. cordifolia (2n = 30 and 34) and L. revoluta (2n = 38, 40 and 44). The
difference in chromosome number between the two cytotypes of L. cordifolia is
accompanied by differences in karyotype and morphological discontinuities. Thus, even
though further studies are required, splitting the taxon into two taxa seems reasonable.
The difference in chromosome number among different cytotypes of L. revoluta was also
accampained by an immense difference in karyotype without showing any morphological
differences and discontinuities. No trend in ploidy levels could also be drawn both in the
present study and in the studies done so far. Such a difference might also suggest the
plants may belong to different biological species. Further studies in the line of
chromosome cytology and molecular systamatics might resolve the taxonomic
controversy and thus highly recommendable.
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Biology