ACHILLEA MILLEFOLIUM COMPLEX IN CANADA AND PORTIONS OF THE UNITED STATES

• Published in: Canadian Journal of Botany
• Main Authors: Mulligan, Gerald A., Bassett, I. John
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1959
• Subjects: Plant Science; Canada; Pacific; Nutt; Newfoundland; Alaska; Aleutian Islands; Prince Edward Island
• Online Access: http://dx.doi.org/10.1139/b59-007; http://www.nrcresearchpress.com/doi/pdf/10.1139/b59-007

The chromosome numbers of plants of the Achillea millefolium complex from 27 locations in North America are reported. The levels of polyploidy found are correlated with diameters of the pollen grains. Measurements of pollen grains from more than 300 herbarium specimens are used as an indication of the occurrence of tetraploid and hexaploid species of Achillea in Canada. The results of some crossing experiments are also reported. It is concluded that the common Achillea of North America is tetraploid and is the native A. lanulosa Nutt. It extends from the Pacific to the Atlantic coasts, as far south as California in the west and Pennsylvania in the east, and to northern Canada and Alaska. Another native species, hexaploid Achillea borealis Bong., extends along the Pacific coast from southern California to the Aleutian Islands and along the northern shorelines of Alaska and Canada. A Eurasiatic hexaploid, A. millefolium L. s. str., has been sparingly introduced into Newfoundland, Prince Edward Island, Nova Scotia, and perhaps elsewhere along the Atlantic seaboard. In eastern Canada a male-sterile purple-flowered hexaploid also occurs. This hexaploid escapes from cultivation and forms localized patches. It undoubtedly has been selected from the Eurasiatic A. millefolium L. s str.