MORPHOLOGICAL AND CYTOLOGICAL ANALYSES IN CYLINDROPUNTIA (CACTACEAE): THE TAXONOMIC CIRCUMSCRIPTION OF C. ECHINOCARPA, C. MULTIGENICULATA, AND C. WHIPPLEI

A morphological and cytological study was conducted to elucidate the taxonomic circumscription of Cylindropuntia multigeniculata and its relationship to C. echinocarpa and C. whipplei. Morphological analyses included iterations of multivariate techniques including principle factor analysis, discrimi...

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Published in:Journal of the Botanical Research Institute of Texas 2016-12, Vol.10 (2), p.325-343
Main Author: Baker, Marc A.
Format: Article
Language:English
Subjects:
SYSTEMATICS
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Summary:A morphological and cytological study was conducted to elucidate the taxonomic circumscription of Cylindropuntia multigeniculata and its relationship to C. echinocarpa and C. whipplei. Morphological analyses included iterations of multivariate techniques including principle factor analysis, discriminant function analysis, and multivariate analysis of variance. Results suggested a geographic ring of two morphological clines where westernmost diploid populations of C. whipplei van whipplei intergrade to the northeast with diploid populations of C. multigeniculata and intergrade to the south with tetraploid populations of C. whipplei. Primarily, results indicated that C. multigeniculata represents a group of populations with a number of distinctive morphological traits that suggest it is not of hybrid origin and that it is worthy of taxonomic recognition at the species level. Similarly, tetraploid populations of C. whipplei collectively possess a number of distinctive morphological traits, as well as a distinct chromosome number, and are worthy of taxonomic recognition at the varietal level as C. whipplei var. enodis. Se realizó un estudio morfológico y citológico para elucidar la circunscripción taxonómica de Cylindropuntia multigeniculata, incluyendo sus relaciones con C. echinocarpa, y C. whipplei. El análisis morfológico incluyó varias técnicas multivariadas; análisis de componentes principales, análisis de funciones discriminantes y varianza de análisis multivariado. Los resultados sugieren un anillo geográfico de dos gradientes morfológicos en el cual las poblaciones diploides más al oeste de C. whipplei var. whipplei intergradúan al noreste con las poblaciones diploides de C. multigeniculata; e intergradúan hacia el sur con poblaciones tetraploides de C. whipplei. Primeramente, los resultados indican que C. multigeniculata representa un grupo de poblaciones con un numero de caracteres morfológicos distintos que sugiere no es de origen hibrido y es factible de reconocerse al nivel de especie. De la misma manera, las poblaciones tetraploides de C. whipplei colectivamente posee un numero de caracteres morfológicos distintos, así como un numero cromosómico diferente, y son también factibles de reconocerse taxonómicamente a nivel de variedad como C. whipplei var. enodis.
ISSN:1934-5259