Panarctic Flora

860706-08 The Erigeron grandiflorus aggregate E. koraginensis, E. muirii, E. porsildii

Geography: Asian (N) - amphi-Pacific/Beringian - Cordilleran.

Notes: Murray and Elven: This group is broadly amphi-Pacific and amphi-Beringian group, sometimes considered collectively under the name Erigeron grandiflorus. Nesom and Murray (2005) and Nesom (2006b) revised the northwestern North American taxa as three species: E. muirii, E. porsildii, and the non-arctic E. grandiflorus s. str. The Asian parts are in need of a combined morphological, cytological, and molecular analysis. Two North American names - E. grandiflorus Hook. 1834 and E. muirii A. Gray 1882 - have been extensively applied also in northeastern Asia but we doubt their relevance for Asian plants. Two northeastern Asian names are E. komarovii Botsch. 1954 and E. koraginensis (Kom.) Botsch. 1954. We provisionally follow Nesom and Murray (2005) and assign the proven arctic plants to three species: the northern and northeastern Asian E. koraginensis (by Nesom and Murray as E. komarovii), the narrowly American Beringian E. muirii, and the more broadly American Beringian E. porsildii.

Cody (in comment) reported E. grandiflorus s. str. to approach the Arctic in the northern Yukon Territory. Nesom and Murray (2005) restricted this name to a more southern Cordilleran plant with its northern limit in south-central British Columbia and southern Alberta.

Porsild's arctic and near-arctic northwestern North American E. grandiflorus var. arcticus differs from both E. grandiflorus s. str. and the northern and northeastern Asian plant(s) in several non-overlapping features and was described by Nesom and Murray (2005) as E. porsildii.

The northern Alaskan plant named as E. muirii is morphologically distinct both from the northern and northeastern Asian plant(s), from the northwestern Canadian E. porsildii, and from western North American E. grandiflorus. It should be treated as a species restricted to northern Alaska and the Yukon Territory and was accepted as such by Nesom and Murray (2005).

The arctic Asian plants labeled in herbaria (ALA, O, S) as E. komarovii, E. koraginensis, E. grandiflorus, and E. muirii may belong within one species. It is our opinion that all these Asian plants differ morphologically from both E. grandiflorus s. str. and E. muirii. Their closest North American counterpart morphologically may be E. porsildii. The priority name of the northeastern Asian plant(s) is disputed (see below).