CHROMOSOME NUMBERS OF CANADIAN WEEDS. I

Abstract

The chromosome numbers of 58 Canadian weeds are reported. Counts obtained on material of Ambrosia psilostachya DC. and Epilobium angustifolium L. differ from those obtained by other workers. The chromosome numbers of the following species had not previously been reported: Silene cserei Baumg. 2n = 24; Axyris amaranthoides L. 2n = 18; Erigeron philadelphicus L. 2n = 18; Lepidium ramosissimum Nels. 2n = 64; Dracocephalum parviflorum Nutt. 2n = 14; Rumex fennicus Murb. 2n = 40; R. occidentalis Wats. 2n = ca. 140; R. stenophyllus Ledeb. 2n = 60. The significance of some of these chromosome numbers is discussed.