Karyotypic characteristics of Cenchrus longispinus (Hack.) Fernald (Poaceae)

Cenchrus longispinus (Hack.) Fernald (Poaceae), as a weed, is native of America, but has also been introduced in other countries including Iran in the recent years. In this study, karyotypic features in one population of this species was studied. As such, microscopic slides of root tip meristem cells were prepared using the classical squash technique and aceto-iron-hematoxylene staining. The chromosome number in this species was 2n=34 (x=17). Total length, the longest, the shortest and the mean length of chromosomes were 13.07, 1.08, 0.52 and 0.77 ± 0.12 μm, respectively. The karyotype, with the formula of 16m+1sm (16 metacentric and one submetacentric chromosome in a haploid set) without any satellite chromosomes, is classified as 1B according to the Stebbins method. Thus it could be considered as a wild and primitive species with a relatively symmetrical karyotype.