No abstract

The amount of DNA varies widely in 20 shrubby Oxalis species analyzed, ranging from 1.76 pg in O. alstonii to 33.00 pg in O. dispar. This wide variation in DNA content coincided with a wide variation in chromosome size and shape. Numerical taxonomy methods showed that this variation in chromosome size and shape in shrubby Oxalis is mainly due to extra DNA. It was also possible to arrange the 20 species examined in six different groups on the basis of karyotypic similarities.Key words: Oxalis, DNA content, chromosome evolution, multivariate analysis.

No abstract

No abstract

Synaptonemal complexes (SCs) were measured in large samples (16-31) of pachytene nuclei from five different plants of Crepis capillaris, with the aim of conducting a systematic study of intra-plant and interplant SC length variation. Individual plants showed considerable variation in SC length among cells (average range= 1.83x), which is presumed to reflect stage-related differences in chromosome and SC length during pachytene. The five plants selected for study showed highly significant differences in SC length. These differences are interpreted as real differences in the means and ranges of SC lengths in different genotypes rather than, for example, sampling effects. Mean SC lengths at pachytene and mean chiasma frequencies at metaphase I show signs of being positively related, but the correlation is statistically non-significant, indicating a need for more extensive study.