Panarctic Flora

630620 Oxytropis arctica R. Br.

• R. Br., Chlor. Melvill.: 20 (1823). Lectotype (K): Canada: the Northwest Territories?, Melville Island the Winter Harbour area, 1819-1820, leg. Mr. Beverley (Welsh 1995: 275).

Geography: Asian (N) & North American (NW).

Notes: Elven and Murray: Four geographical and morphological elements have been proposed assigned within Oxytropis arctica: a red/blue-flowered plant of the Canadian Arctic Archipelago and surroundings (O. arctica s. str.), a red/blue-flowered plant of the Taimyr Peninsula and surroundings in northern Siberia (subsp. taimyrensis), a white-flowered plant of western Alaska (var. barnebyana) and a red/blue-flowered plant in the same area (no name).

Yurtsev (1986, PAF proposal, comments) considered O. arctica a red/blue-flowered lineage and accordingly re-assigned var. barnebyana as a subspecies of O. sordida in a white-flowered lineage. Within O. arctica (excluding var. barnebyana), Yurtsev accepted two subspecies: the Canadian subsp. arctica and the northern Siberian subsp. taimyrensis. These are separated by a gap of 100-110 longitude between the lower Lena River in Kharaulakh and the Canadian Arctic Archipelago. He contended that the American race is derived from the Siberian one, with reduced number of leaflets and flowers but increased chromosome number 8x -> 10x-12x, and that the distinctions between the races are quantitative. Yurtsev stated subsp. arctica to be absent from Alaska but he mentioned plants from the Seward Peninsula (and also annotated such ones as O. arctica in ALA). American botanists accept O. arctica from western Alaska and also from northern Alaska and the Yukon Territory. This reduces the gap between the Asian and American parts of the range to 60 longitude. Still, there is an appreciable disjunction associated with some morphology and a ploidy difference, and our view is that subsp. taimyrensis may be different enough from the North American plants to merit rank as species.

The molecular data of Jorgensen et al. (2003) connected the red/blue-flowered plants in northern Alaska to the also red/blue-flowered plants in the Canadian Arctic Archipelago (type area of O. arctica) but found the red/blue-flowered plants in western Alaska different. They also found the white-flowered plants (assigned to var. barnebyana) to differ between western and northern Alaska regions but to connect closely to red/blue-flowered plants locally. Yurtsev's separation between O. arctica and O. sordida subsp. barnebyana, and his retention of "barnebyana" as a separate taxon, is not supported by these molecular data. Both molecules and morphology support inclusion of var. barnebyana (as typified) in western Alaskan O. arctica and not in O. sordida (which in any case is a problematic name to apply in northeastern Asia and Beringia, see notes to O. sordida).

The difference found in molecular markers between the plants in western Alaska and those in northeastern Alaska and northern Canada has not yet been taken into account taxonomically. There are morphological differences between the populations in these two American regions and probably differences in ploidy levels among all three regions (i.e., including Taimyr-Lena). The western Alaskan plants are counted as hexaploid (including O. koyukukensis), the northern Siberian ones as octoploid, and the northern Canadian ones as decaploid and dodecaploid. This pattern does not support Yurtsev's statement that the lowest ploidy level (and assumed origin) is found in northern Siberia. Different combinations of original diploid genomes may be involved. However, there are only a few counts from North America and the real situation may be different.

In summary, the current data suggest that there are three taxa within O. arctica s. lat.: one northern Siberian (subsp. taimyrensis, red/blue-flowered), one western Alaskan (var. barnebyana, red/blue and white-flowered), and one northwestern Canadian and probably northeastern Alaskan (subsp. arctica, red/blue and white-flowered). The red/blue-flowered taxa O. roaldii and O. koyukukensis belong in the same relationships. They were accepted by Yurtsev. We provisionally enter them below. A full revision of this group is needed, taking the entire variation into account and not assuming a priori a special importance of red/blue vs. white flowers. The combined ploidy, morphology, and molecular data suggest that the three taxa perhaps better are treated as three species: one in northern Alaska and northwestern Canada (O. arctica s. str.), one in western Alaska (O. "barnebyana"), and one in Taimyr and northern Yakutia (O. taimyrensis, or rather perhaps O. karga). However, we enter them for the Checklist under the racial names.