Abstract: The present paper reports the chromosome numbers and karyotypes of 11 populations of six species of Sect. Bromatorrhiza and Sect. Rhizirideum in Allium (Liliaceae). The results are as follows: A. cyathophorum Bur. et Franch.: 2n＝2x＝16=12m+4sm (2SAT). A. przewalskianum Regel: 2n=4x＝32＝28m+4st(2SAT) and 2n=4x＝32= 28m+2sm+2st(2SAT) respectively from Zhagyab in Xizang and Lixian in Sichuan. A. polyrhizum Turcz. ex Regel: 2n=4x=20m+8sm+4t(2SAT). A. mongolicum Regel: 2n=2x=16=14m+2st(2SAT). A. senescens L.: 2n=4x＝32＝28m+2sm+2st(2SAT) and 2n=4x＝32＝24m+4sm+4st(2SAT) respectively from Ulrung-do (DPRK) and Horqin Zuoyi Houqi, Nei Monggol. A. tuberosum Rottl. ex Spreng.: Four populations of this species were studied. One from Yongji in Shanxi is diploid with 2n=2x＝16＝14m+2st (2SAT) and the other three populations respectively from Lixian, Yulong and Sanwayao in Sichuan are all tetraploid with 2n=4x＝32=28m+4st(2SAT). The chromosome numbers and karyotypes of A. przewalskianum, A. polyrhizum and A. mongolicum are reported here for the first time. The wild diploid population of A. tuberosum is found here for the first time in China. In additon, the origin of cultivated A. tuberosum and the karyotypical differentiations among the populations of A. cyathophorum, A. przewalskianum and A.senescens are discussed.

Key words: Allium, Karyotype, Population