Valeriana jatamansi, a medicinally important species of the family Valerianaceae, has been cytologically studied in different geographical areas of North-Western Himalayan region of India. The tetraploid cytotype with chromosome numbers 2n=32 is in conformity with the earlier reports of the species from different parts of the world. An octoploid cytotype (2n=64) makes a new addition for the spe...

Three accessions of Brachiaria brizantha, three of B. humidicola, and two interspecific hybrids between B. ruziziensis and B. brizantha were analyzed with regard to their mitotic behavior in root tips. All these genotypes revealed chromosome elimination or lack of chromosome affinity in previous analyses of microsporogenesis. Analyses of root tips showed a normal mitotic division in all accessi...

A cytological analysis of the microsporogenesis was carried out in the Agave tequilana and A. angustifolia species. Several abnormalities such as chromosomal bridges, lagging chromosomes, micronuclei, monads, dyads and triads were found. The morphological analysis of the pollen, together with the above-mentioned 2n microspores, allowed us to confirm the presence of 2n pollen as well as its freq...