Cytological Studies in Some Members of Cyperaceae

Abstract

Cyperaceae is one of the large monocotyledonous families of cosmopolitan distribution comprising over 5000 species in 120 genera. Karyomorphology and meiosis in 19 species belonging to Ascopholis, Cyperus s. l. and Lipocarpha have been studied. Karyotypic analysis has been carried out for the first time in Ascopholis gamblei (2n=80), Cyperus tenuispica (2n=26), C. pilosus (2n=36, 68), C. diffusus (2n=38), C. pseudokyllingioides (2n=40), C. tenuiculmis (2n=44), C. rubicundus (2n=42, 50, 52), C. sanguinolentus (2n=50), C. corymbosus (2n=108), C. dubius (2n=112), C. cyperinus var. laxatus (2n=136), C. cyperinus var. pictus (2n=152), C, pangorei (2n=208), and Lipocarpha sphacelata (2n=38). The remaining species, C. haspan (2n=26), C. difformis (2n=36), C. distans (2n=58), C. procerus (2n=64), C. laevigatus (2n=88) and L. chinensis (2n=26), are studied because of discrepancies in the previous chromosome number reports. A deviation from the previous reports has been noticed in C. procerus and C. laevigatus, whereas the remaining taxa conform to one of the earlier reports. Ascopholis, a monotypic genus falls under the series having the basic number of x=5. Of the 16 species of Cyperus studied, 6 species conform to the basic number of x=8, 3 fit into the basic number of x=9 and one falls under the basic number of x=13. New basic numbers such as x=5, 11, 19 and 29 are suggested for remaining 6 species since they do not fit into any of the existing basic numbers known so far. Two species of Lipocarpha fall under the basic number of x=13 and 19. The karyotypes of all the species are found to be symmetrical with the predominance of chromosomes having median centromeres. In all the taxa investigated, the chromosomes have been found to have localized centromeres. Mixoploidy has been observed in C. pilosus and C. rubicundus. Structural changes including fragmentation and duplication of single or whole set of chromosomes are suggested to be responsible for bringing about the wide range of chromosome numbers in the taxa studied. The taxonomic implications of cytological findings are discussed.