Cytotaxonomy and Breeding System of the Genus Biscutella (Cruciferae)

Olowokudejo, J. D. ; Heywood, V. H. (1984)


Chromosome counts were determined for 46 populations of Biscutella representing 28 taxa. The genus was found to contain diploid taxa with 2n = 12, 16 and 18, tetraploid taxa with 2n =36 and hexaploid taxa having 2 n = 54. B. laevigata L. s. 1. consists of diploid and tetraploid populations which are poorly differentiated morphologically. Tetraploid B. laevigata s. 1. and hexaploid B. variegata Boiss. & Reuter (s. 1.) are characterized by chromosomal instability. The variation in" chromosome numbers and the occurrence of polyploidy is discussed in relation to the taxonomy of the genus. An investigation of the breeding system showed that most of the annual species were self-compatible and partly inbreeding and most of the perennial species self incompatible and, therefore, outbreeding, while one annual species, B. cichoriifolia Lotsel., showed both systems