Cytological Studies in the Genus Alysicarpus Neck

Abstract

In the genus Alysicarpus karyotypic details were studied in seven species. In A. bupleurifolius DC., A. hamosus Edgew., A. pubescens Law., A. rugosus DC., A. tetra-gonolobus Edgew. and A. vaginalis DC. the chromosome numbers were found to be 2n=16. A. belgaumensis Wight. is the only species with chromosome number 2n=22. For A. belgaumensis Wight. (2n=22) and for A. pubescens Law. (2n=16) are new reports. The total chromosome length varied from 77.44μm (A. belgaumensis Wight.) to 43.24, μm (A. buplerifolius DC.). The TF percentage varied from 46.17 (A. hamosus Edgew.) to 37.58 (A. tetragonolobus Edgew.).
When classified according to Stebbins' two-way system of classification of karyotype asymmetry A. hamosus Edgew. belongs to 1 A and A. pubescens Law. belongs to 2A, the remaining five species belong to 2B. As only three classes were represented in the seven species analysed the karyotype asymmetry appears to be of a lower degree.
It was seen that, for the length of individual chromosome pairs the correlation coefficients were higher pointing towards close relationships. However, the coefficients of correlation for arm ratios being very low, reveal the possible mode of diversification due to structural alterations like inversions and translocations bring-ing about changes in the arm ratios.