Artemisia carruthii and A. frigida of the subgenus Artemisia and A. filifolia and A. spinescens of the subgenus Dracunculus all have chromosome numbers based on x = 9. Diploid (2n = 18) karyotypes of each species are composed of large, medium, and small chromosomes that are mainly metacentric and submetacentric. The individual karyotypes are similar but distinctive. Artemisia filifolia's karyotype and chemistry is quite similar to that of Section Tridentatae, but A. filifolia has significant morphological differences with respect to the Tridentatae. Artemisia spinescens includes a tetraploid (2n = 36) population as well as diploid populations. Karyotypic analysis of a tetraploid A. spinescens suggests that it is an autotetraploid, thus carrying out a common theme in Artemisia (autopolyploidy).
McArthur, E. Durant and Pope, C. Lorenzo
"Karyotypes of four Artemisia species: A. carruthii, A. filifolia, A. Frigida, and A. spinescens,"
Great Basin Naturalist: Vol. 39
, Article 3.
Available at: http://scholarsarchive.byu.edu/gbn/vol39/iss4/3