Panarctic Flora

641008 Potentilla pensylvanica L.

• L., Mant. Pl.: 76 (1767). Described from North America and northern Asia. Lectotype (LINN): Herb. Linn. 655.12, leg. Arduino 13 (Fernald 1935a: 288).
• Potentilla sibirica Th. Wolf, Biblioth. Bot. 17, 71: 188 (1908). Described from Siberia.
• Potentilla brooksensis Jurtz., Bot. Zhurn. 78, 11: 82 (1993). Holotype (ALA!): Alaska: the northeastern Brooks Range, Mt. Michelson Quad., the Hulahula River area, 12. July 1976, leg. H. Haid 98219.

2n= (1) 14 (2x). - U.S.A. (New Mexico). - Ward and Spellenberg (1988).
(2) 28 (4x). - Europe (SW), Siberia (S), Alaska, Canada. - Several reports, more than 40 counts.
Not included: Some old reports of 2n = 28, 35, and 84 (for Potentilla pensylvanica s. lat.) should perhaps be assigned to other species.

Geography: European (S) & Asian & North American: RFE* ALA CAN.

Notes: Elven: Potentilla pensylvanica has been collected from the Arctic in the Brooks Range in Alaska (ALA). In Canada, Cody (1996) mapped it from the British Mountains (Yukon Territory), confirmed by Kohli and Packer (1976) to reach the Arctic along the lower Mackenzie River (N.W.T.), and also stated by Cody (in comment) to reach the arctic shores of Hudson Bay. It is adventive in Provideniya in East Chukotka.

Yurtsev: Potentilla brooksensis in the Brooks Range, Alaska has been described due to its outstanding deviation in various parameters from the standards in this aggregate (they are of rough structure), which I am inclined to explain by speciation in a marginal population.

Ertter, Murray, and Elven: We agree that P. brooksensis deviate but still consider it part of the pronounced polymorphy of P. pensylvanica in Alaska and the Yukon Territory. Ertter et al. (2011) and Soják (in comment) included it in P. pensylvanica. However, a closer study of the Beringian parts of P. pensylvanica might reveal variation supporting more than one species (Ertter in comment).