Cromosomas en Vernonia platensis y especies afines (Asteraceae)

DEMATTEIS, M.

Bonplandia

Instituto de Botánica del Nordeste

Lugar: Corrientes; Año: 1997 vol. 9 p. 259 - 264

The somatic chromosomes of Vernonia platensis and three others closely related species were analyzed. All these species belong in the subsection or series Flexuosae, which is the only American group with the primitive basic chromosome number x=10. In this paper two new cytotypes for V. platensis are reported and the karyotypes of V. verbascifolia and of four cytotypes of V. platensis are presented for the first time. The results of the chromosome analysis were the following: V. flexuosa, 2n=40 (28m + 12sm); V. lepidifera, 2n=20 (8m + 2m-sm + 10sm), V. platensis, 2n=20 (10m + 2m-sm + 8sm), 2n=40, 2n=60, 2n=80 and V. verbascifolia, 2n=20 (8m + 4m-sm + 8sm). The  4x, 6x, and 8x cytotypes of V. platensis present the same karyotype that the diploid suggesting an autoploid origin. The karyotypes of the species here reported differ principally in total length, asymmetry and number of metacentrics and submetacentrics. They show also variation in number, form and location of the satellites. The results are discussed in relation to the taxonomic position of the species and to previous chromosome studies in the group.