Calamagrostis epigejos (Poaceae) in North America, especially Ontario

Abstract

The Eurasian grass, Calamagrostis epigejos (L.) Roth, has been both deliberately and accidentally introduced to North America. Deliberate introductions have usually been destroyed because the plants were weedy and difficult to confine. Introductions at approximately 50 sites, most of them accidental, are documented. While the grass sometimes is the dominant species over several square metres and can out-compete some other weedy species, only at two sites is it known to have spread more than 10 km in a 30-year period. One site is Ontario, Canada, along the road between Espanola and Whitefish Falls, and the other is Liberty State Park in New Jersey, U.S.A. There have been major earth moving projects at both sites so that spread of rhizomes as well as seed dispersal may have been involved. Data analyses of 16 characters used, or possibly useful, in recognizing intraspecific taxa are presented. Taxonomic recognition of C. epigejos as an amphimictic, polyploid complex is discussed. Application of the treatment given by Tzvelev to our data suggests that (i) ssp. extremiorentalis Tzvelev and ssp. macrolepis (Litv.) Tzvelev have each been introduced once into North America; (ii) most specimens in North America belong to ssp. epigejos, ssp. glomerata (Boiss. and Buhse) Tzvelev, or ssp. meinshausenii Tzvelev, but it is not always possible to distinguish among these subspecies with confidence; and (iii) C. epigejos var. georgica (C. Koch) Ledeb., as recognized by Fernald, is probably synonymous with ssp. glomerata. Plants collected from five sites in Ontario had chromosome counts of 2n = 28 + 4B. Plants of C. epigejos ssp. macrolepis from New York were 2n = 42.