Chromosome counts of some wetland cyperaceous species from the Mekong Delta, Vietnam

Chromosome numbers were counted in root tip cells of 6 cyperaceous species growing in wetlands in the Mekong Delta, Vietnam. The results were as follows: Cyperus haspan, 2n=26; Eleocharis dulcis, 2n=ca. 212; Eleocharis spiralis, 2n=42; Fimbristylis ferruginea, 2n=20; Fimbristylis polytrichoides, 2n=10; Lepironia articulata, 2n=34. They were reported here for the first time using plant materials from Vietnam. Furthermore, the results of 2 species, Eleocharis spiralis and Lepironia articulata, were the first to be reported for these species. In addition, the dimorphism of Eleocharis dulcis shoots representing emerged and submerged culms was recorded.