Abstract
Morphology of chromosomes at the pachytene stage of meiosis was studied in three diploid species of Arachis, viz., A. chacoense and A. villosa (the A-genome species) and A. batizocoi (the B-genome species). They were identified individually on the basis of total length, arm-ratio, nucleolus attachment, and proportion and disposition of heterochromatin. Idiograms were given to individual species. The A-genome is characterised by the presence of the small A-chromosome, which was completely heterochromatic and a single chromosome with heterochromatic shortarm. The B-genome is characterised by the absence of the A-chromosome and the presence of two chromosomes with heterochromatic short arm. The individual chromosomes of all the three species were compared to those of groundnut. The possibility for the derivation of the genomes of A. hypogaea from A, villosa or a species similar to that, and A, batizocoi has been discussed.
