Estudios morfo-anatómicos, cromosómicos y palinológicos en especies de Stemodia (Scrophulariaceae)

Stemodia L. is a genus with 49 species, belonging to the Scrophulariaceae family. In South America this genus is very well represented whit a total of 20 species. In some South American species its great morphologic variability makes difficult its identification and the limits with related species...

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Autor principal: Sosa, María de las Mercedes
Otros Autores: Fernández, Aveliano
Formato: Tesis doctoral
Lenguaje:Español
Publicado: Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias 2020
Materias:
Estudios morfo-anatómicos
Estudios cromosómicos
Estudios palinológicos
Acceso en línea:http://repositorio.unne.edu.ar/handle/123456789/472
Aporte de:
RIUNNE - Repositorio Institucional de la Universidad Nacional del Nordeste (UNNE) de Universidad Nacional del Nordeste
id I48-R184-123456789-472
record_format dspace
institution Universidad Nacional del Nordeste
institution_str I-48
repository_str R-184
collection RIUNNE - Repositorio Institucional de la Universidad Nacional del Nordeste (UNNE)
language Español
topic Estudios morfo-anatómicos
Estudios cromosómicos
Estudios palinológicos
spellingShingle Estudios morfo-anatómicos
Estudios cromosómicos
Estudios palinológicos
Sosa, María de las Mercedes
Estudios morfo-anatómicos, cromosómicos y palinológicos en especies de Stemodia (Scrophulariaceae)
topic_facet Estudios morfo-anatómicos
Estudios cromosómicos
Estudios palinológicos
description Stemodia L. is a genus with 49 species, belonging to the Scrophulariaceae family. In South America this genus is very well represented whit a total of 20 species. In some South American species its great morphologic variability makes difficult its identification and the limits with related species are not always clearly defined. In the present study the taxonomic and systematic significance of morphological, anatomical, chromosomal, and palynological characters is evaluated. The exomorphologic analysis permitted the selection of valid characters to elaborate a key for the identification of the species. The anatomical study revealed the existence of characters that can be useful for their differentiation both in leaf and in stem. The useful anatomical characters of the leaves to differentiate the species are: the anticlinal walls of the epidermical cells, types of trichomes, types of stomata and the mesophyll structure. The fundamental difference was observed in the stem, in characters such as the contour of the stem, the presence or absence of aerenchyma, collenchyma and medullar lagoon. On the basis of these differences a key for the identification was elaborated to differentiate the species studied. All the studied species showed basic chromosome number x = 11, with three ploidy levels in Stemodia hyptoides. A high percentage of pollen fertility was observed. The karyotypes of the species of Stemodia presented in this thesis constitute the first report for the genus. The similarity of the karyotypic formula between the diploids and the polyploids taxa suggests that they probably would not have experience greated structural changes during the diversification of the species. Morpho-anatomical studies were carried out in Stemodia hyptoides because of three different levels of ploidy were registered. The results obtained here indicate that most morphologic variation should be produced by the “gigas” effect; which communly occurrs in polyploids. Because of the diploid populations of S. hyptoides resemble morphologically to S. stricta, morpho-anatomical characters of both species were analyzed comparatively. The statistical analysis demonstrated that an important number of features allow to differentiate both species. The palynological studies performed in Stemodia species shows a high homogeneity in the characters evaluated. They suggest that the genus is stenopalynous, although small differences in some species as in shape and size are observed. The obtained results reveal that polyploidy would have been one of the mechanisms that have contributed to the evolution of Stemodia. This has produced a great variability in some species making difficult its taxonomic identification, since the species with the different ploidy levels are morphologically more variable than the species with 2n=22.
author2 Fernández, Aveliano
author_facet Fernández, Aveliano
Sosa, María de las Mercedes
format Tesis doctoral
author Sosa, María de las Mercedes
author_sort Sosa, María de las Mercedes
title Estudios morfo-anatómicos, cromosómicos y palinológicos en especies de Stemodia (Scrophulariaceae)
title_short Estudios morfo-anatómicos, cromosómicos y palinológicos en especies de Stemodia (Scrophulariaceae)
title_full Estudios morfo-anatómicos, cromosómicos y palinológicos en especies de Stemodia (Scrophulariaceae)
title_fullStr Estudios morfo-anatómicos, cromosómicos y palinológicos en especies de Stemodia (Scrophulariaceae)
title_full_unstemmed Estudios morfo-anatómicos, cromosómicos y palinológicos en especies de Stemodia (Scrophulariaceae)
title_sort estudios morfo-anatómicos, cromosómicos y palinológicos en especies de stemodia (scrophulariaceae)
publisher Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias
publishDate 2020
url http://repositorio.unne.edu.ar/handle/123456789/472
work_keys_str_mv AT sosamariadelasmercedes estudiosmorfoanatomicoscromosomicosypalinologicosenespeciesdestemodiascrophulariaceae
bdutipo_str Repositorios
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