Abstract: This paper reports chromosome numbers and karyotype analysis of 12 Aristolochia species from China for the first time. The results are shown in Table 1 and 2.The general aspects of the chromosome of this genus are small in size, mostly metacentric and submetacentric, the secondary constrictions are nearly all on the long arms, karyotypes are 1A, 2A, 3A, 1B. 2B and considered as symmetric types.Besides the previously reported x=6、7, x=8 is suggested here as one of the basic number of the genus owing to the frequent occurrence of 2n=32 in Subgen.Slphisia. According to the karyotype analysis, species with 2n=32 seem to be allotetraploids.

Key words: Aristolochia, Chromosome, Karyotype