The separation of Carex disticha and Carex sartwellii and the status of Carex disticha in North America
To clarify the relationship between the Eurasian Carex disticha and the North American Carex sartwellii, 38 morphological characters were measured in 30 specimens of each. Various qualitative features were also scored. Through analysis of variance (ANOVA), a reduced number of 10 important continuous characters was obtained and the sample of each taxon was increased to 50. ANOVA of these 10 characters revealed that perigynium length and perigynium beak length were the most important discriminating characters, but in a scatter diagram of these two, 15% of the sample occupied a region of overlap. Principal-component analysis and discriminant analysis using the 10 characters resulted in a separation of the two groups, but a small region of overlap existed in both cases. The two taxa are distinct by virtue of accumulation of small morphological and other differences in a number of characters, rather than by sharp differentiation in a few characters. Carex disticha has larger perigynia with beaks (0.8–)1–1.5(–2.3) mm long, whereas C. sartwellii has smaller perigynia with beaks 0.4–1(–1.2) mm long. All distinguishing features are discussed and a key is provided. Immature vouchers for the occurrence of C. disticha in southwestern Quebec are confirmed on the basis of features of the inflorescence. The only other North American station of C. disticha, discovered in Simcoe Co., Ontario, in 1972 and extant in 1986, is also confirmed in the numerical analyses.