Flora of North America species comparison

The chromosome number reported for Carex bigelowii subsp. lugens from eastern Asia indicates that there may be a significant genetic difference between populations of the two regions.

Most floras (I. L. Wiggins and J. H. Thomas 1962; E. Hultén 1968; A. E. Porsild and W. J. Cody 1980) recognize two species, C. lugens and C. consimilis, in the western Arctic, with greater affinities to the eastern Asian members of the complex than to the eastern C. bigelowii. These treatments usually separate C. lugens by the cespitose habit, leaves less than 2 mm wide, and setaceous proximal bract. Careful study of the complex indicates that although there are cespitose and rhizomatous morphs, leaf width, bract width, perigynium size and shape all vary considerably within and between populations and variation is not correlated with habit. It is not known whether variation in habit is due to genetic differences or merely to plant responses to differences in substrate and soil moisture. Long-rhizomatous plants tend to occur in dry tundra, and short-rhizomatous plants tend to occur in wet, peaty muskeg. For that reason, the group is recognized as a single taxon that clearly needs further study.

Carex bigelowii subsp. lugens may intergrade or hybridize with C. scopulorum at the southern edge of the range in the Yukon, as indicated by the wider leaves and large range of variation in the area. Carex sphacelata T. Holm and C. chionophila T. Holm, also described from the Yukon, appear to be hybrids between C. bigelowii subsp. lugens and C. aquatilis.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Carex bigelowii subsp. bigelowii is highly variable in height and shape, stipe length, and color of perigynia. The isolated populations at the southeastern extreme of the range (New York and New England) tend to have larger, more apically acute perigynia than in the northern parts of the range. Although usually distinct from the western subsp. lugens, occasional eastern plants are not distinguishable based on morphology.

The ecology of Carex bigelowii subsp. bigelowii has been extensively studied (K. A. Kershaw 1962; T. V. Callaghan 1976; R. W. Fonda and L. C. Bliss 1966). Chromosome numbers reported for subsp. bigelowii are lower than the number reported for subsp. lugens, and indicate that there may be considerable genetic differentiation between these taxa as suggested by Hultén’s hypothesis that these are the two ends of a circumpolar Rassenkreise.

(Discussion copyrighted by Flora of North America; reprinted with permission.)