This study demonstrates the occurrence of 1,8-cineole/camphor/camphene chemotype of A. spicigera but there is also significant chemical variation between the studied populations. The findings showed the studied oils have good antibacterial activity, and thus potential to be used as natural health products.

Summary Chromosome counts of 6 populations of 4 species in the genus Artemisia from the family Asteraceae are reported. All taxa were collected from west provinces of Iran. Three species, Artemisia fragrance, A. spicigera and A. scoparia, were not accordance with previous counts. The most of studied taxa had the basic number xϭ9 with ploidy levels ranging from 2x to 8x, but A. incana had xϭ8. Both diploidy and triploidy were found for A. incana that can be regarded as the sign of new species generation. This is the first report for ploidy level 2nϭ8xϭ72 for A. spicigera.

-Mitotic chromosome numbers are reported for thirty-three populations representing four species of Artemisia. In A. incana, chromosome numbers were varied from 2n = 2x = 16, 18 to 2n = 3x = 24. In A. fragrans eight diploid populations (2n = 2x = 18) and three populations with both diploid and tetraploid chromosome number (2n = 2x = 18, 36) were identifi ed. In A. scoparia six populations with chromosome number (2n = 2x = 16) and two populations with different chromosome number (2n = 2x = 16, 18) were found. The highest variation in chromosome number was observed in A. spicigera. In this species; different chromosome numbers (2n = 2x = 18, 2n = 3x = 27, 2n = 4x = 36, 2n = 5x = 45, 2n = 6x = 54 and 2n = 8x = 72) were identifi ed in different populations that collected from different parts of Iran. Polyploidy is confi rmed as the most signifi cant evolutionary trend in chromosome number within the genus.

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