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Cytogeography and reproduction of the Paspalum simplex polyploid complex
M. H. Urbani, C. L. Quarin, F. Espinoza, M. I. O. Penteado and I. F. Rodrigues
Plant Systematics and Evolution
Vol. 236, No. 1/2 (December 2002), pp. 99-105
Published by: Springer
Stable URL: http://www.jstor.org/stable/23644966
Page Count: 7
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Paspalum simplex is a grass distributed throughout the phytogeographic Chaco region in South America from which sexual diploid and apomictic tetraploid races have been reported. We analysed native populations to determine their homogeneity of ploidy level, and the relationship between geographic distribution, ploidy levels, and reproductive systems. The ploidy level was established for 379 plants from 32 wild populations. Tetraploidy and apomixis constitute the most common combination for this species all over the Chaco region. Apomictic hexaploid plants were found associated with 4x populations. Diploids were confined to a small sector of the region. One sexual triploid plant arose from seed harvested in a pure 2x population, and one apomictic 3x plant was found in a mixed 2x-4x population. The results suggest that P. simplex is a core agamic complex characteristic of the Chaco region from which other apomictic polyploid species of the subgenus Anachyris could have evolved.
Plant Systematics and Evolution © 2002 Springer