Publication: Fl. N.W. Coast. 72. 1915.
selected vouchers: WTU
Notes: FNA23: "Although infrequent or local in most parts of its range, Carex cusickii is fairly common in and west of the Cascade Mountains. Reports of C. cusickii from Utah probably are based on specimens of C. diandra. Carex cusickii is more similar to C. prairea than either species is to C. diandra. Both are typically more robust than the latter, having wider leaves and sometimes larger inflorescences and larger perigynia. The characteristics distinguishing the first two, although seemingly unimportant, are constant and appear to have populational significance. Furthermore, the geographic ranges of the species, although contiguous in the western part of the Cariboo Forest Region of southern British Columbia, are wholly discrete except for the remarkable occurrence of C. prairea in Flathead County, Montana. It remains to be determined if any real overlapping or recombining of characteristics occurs among the several species of section Heleoglochin, or whether the difficulty in drawing precise lines between them in the herbarium is merely the consequence of inadequate specimens and reliance on too few characters."