3438 Arctagrostis Griseb.
- Griseb. in Ledeb., Fl. Ross. 4: 434 (1852).
Notes: Tzvelev, Aiken, and Elven: Opinions about the size of the genus Arctagrostis vary from one species (i.e., monotypic, A. latifolia) to about 17 (the International Plant Name Index). Two species or races have been accepted by the vast majority of authors (as A. latifolia and A. arundinacea or subsp. arundinacea). Of the 15 others, 14 are due to three authors: Nash in Britton and Rydberg (1901, three American species, Petrov (1930, six Asian species, all in Yakutia), and Vassiljev (1955, five Asian species). All the additional species are within the relationship of A. arundinacea. More recent authors have not found support for more than two taxa above (e.g., Tzvelev 1976 and later).
Tzvelev (PAF proposal, in comments) considered A. latifolia and A. arundinacea two species with secondary contact and introgressive hybridization but might reluctantly accept them as two subspecies.
Aiken and Lefkovitch (1990) studied the genus, documented considerable phenotypic plasticity within what they considered one species, A. latifolia, with two subspecies, and found only subsp. latifolia in the Canadian Arctic Archipelago although subsp. arundinacea occurs nearby on the North American continent. Other North American studies (e.g., Mitchell and McKendrick 1975; Mitchell 1992) have shown delimitation problems and mixture of ploidy levels. Aiken et al. (2007) chose treatment as two subspecies.
Elven is less reluctant than Aiken to accept two species and finds the secondary contact hypothesis proposed by Tzvelev worth further study. The variation is not clinal. Arctagrostis latifolia s. str. is circumpolar-alpine and its range overlaps with that of the Asian and amphi-Beringian A. arundinacea. Both taxa have been observed to be disjunctly different morphologically even when growing within a few metres from each other (but with different ecology) at several localities on the Chukchi Peninsula and in Alaska. The delimitation and ploidy problems are easier explained by secondary contact than by ongoing differentiation.