Panarctic Flora

3309084 Carex bigelowii Torr.

• Torr., Ann. Lyceum Nat. Hist. New York 1: 67 (1824). Type (PH): U.S.A.: New Hampshire, White Hills.

Geography: Circumpolar-alpine.

Notes: Elven and Schönswetter: Carex bigelowii s. lat. is a polymorphic and widespread arctic-alpine complex. At least 11 names for species or subspecies have been in comparatively recent use for northern taxa, some of them probably representing different taxa at some rank: in northeastern North America and Greenland bigelowii Torr. 1824 and hyperborea Drejer 1841; in Europe bigelowii, rigida Gooden. 1794 (non Schrank 1789), inferalpina Laest. 1839, and nardeticola Holub 1968; in Russia-Siberia bigelowii, nardeticola, rigida, ensifolia Gorodkov 1930, rigidioides Gorodkov 1930, soczavaeana Gorodkov 1930, and arctisibirica Jurtz. 1965; and in Beringia consimilis Holm 1900 and lugens Holm 1900. If only one collective species is considered, the priority name is C. bigelowii Torr.

There has been no thorough circumpolar taxonomic revision of the C. bigelowii group. Published studies are more or less regional. These have proposed different solutions:

(a) One species, C. bigelowii, without formal subdivisions, proposed by some North American authors. Researchers familiar with the variation in both Atlantic, Siberian, and Beringian regions are reluctant to accept this and it is not supported by the molecular results (Schönswetter et al. 2008; Nakamatte and Lye 2008; Dragon and Barrington 2008, 2009).

(b) One polymorphic species, C. bigelowii, with several parapatric to allopatric races circumpolarly and in alpine areas, proposed for Russia by Egorova (1973) with numerous subspecies and applied for North America by Standley et al. (2002) with two subspecies. This approach assigns all (subspecific) taxa to the same level. The morphological and molecular data partly support this solution but with much fewer taxa than proposed by Egorova.

(c) One polymorphic species in the broadly amphi-Atlantic and Siberian areas (C. bigelowii with races) and two or more species in the broadly amphi-Beringian areas (C. consimilis-C. lugens and C. soczavaeana). This is the approach of Egorova (1999). It has some morphological support but is not in accordance with the molecular results.

(d) A series of several, perhaps 6-7, related species that reach the Arctic. This solution is not in accordance with the molecular results.

Initial molecular investigations (Schönswetter et al. 2008, mainly AFLP data), based on samples from throughout the northern regions, did not give support to more than one northern species. Four lineages were identified: a distinct one represented by the central Asian C. orbicularis Boott (described from Kashmir, in subsect. Orbiculares by Egorova 1999), and three much more similar ones collectively representing C. bigelowii s. lat. These three lineages corresponded to three geographically only slightly overlapping groups of samples, and they can perhaps be interpreted as three subspecies:

I. A mainly northeastern North American-Greenlandic lineage including the type areas and material of C. bigelowii s. str. and C. hyperborea. One or two samples from non-arctic parts of northern Scandinavia also assigned here. Morphological data support a larger range in Scandinavia as do the independent investigation by Nakamatte and Lye (2008; AFLP).

II. A European lineage including the type areas and material of C. rigida and subsp. nardeticola. This lineage is supported by samples from the central European mountains, Scotland, Iceland, and the major part of Scandinavian samples. Morphological evidence suggests presence also in eastern Greenland and probably in Jan Mayen.

III. A northeastern European, northern Asian, and Beringian lineage supported by samples identified as subsp. arctisibirica, C. consimilis, and C. lugens. There were no indication of any separation between C. lugens-C. consimilis and C. bigelowii subsp. arctisibirica, and this lineage was close to the other lineages in C. bigelowii. This lineage may also include subsp. ensifolia, subsp. rigidioides, and subsp. soczavaeana.

These AFLP data do not support species rank for C. lugens or C. consimilis. Fairly few samples from northern Asia and northwestern North America were included and none from the Russian Far East. This study should be extended with more samples from these areas and should be combined with a morphological study before a revised taxonomy is proposed. However, it suggests that the extensive split that many authors have accepted in Asia, Beringia, and northwestern North America, compared with the slight or no split accepted in the North Atlantic regions, is due to taxonomic traditions more than to genetic variation. The studies of Dragon and Barrington (2008, 2009) included few samples of C. bigelowii but indicated similar patterns. Carex bigelowii s. str. from Vermont and their var. lugens from Alaska grouped together and in a clade together with the rhizomatous non-arctic Cordilleran C. scopulorum Holm (reaching north to the southern Yukon Territory) and the tussocky eastern North American C. stricta Lam. (reaching north to Quebec and Ontario). In the study of Hendrichs et al. (2004; ITS), samples of C. bigelowii from Finland grouped with Cordilleran C. scopulorum but these authors included no American samples assigned to C. bigelowii.

The solution we have chosen follows the main results from the molecular investigations but without taking the nomenclatural consequences yet. Provisionally, we have grouped the variation into three subspecies following the results of Schönswetter et al. (2008) - subsp. bigelowii, subsp. rigida, and subsp. ensifolia - whereas other taxa proposed from the Beringian regions are commented on under subsp. ensifolia and are entered in the distribution table.