Panarctic Flora

641028 Potentilla uniflora Ledeb.

• Ledeb., Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 5: 543 (1815). Described from "Hab. in Davuria" (Siberia) without reference to specimens or collections. See notes. - Potentilla ledebouriana A.E. Porsild, Bull. Natl. Mus. Canada 121: 226 (1951). Superfluous nomen novum for Potentilla uniflora.

2n= (1) 28 (4x). - Far East (N). - Several reports, numerous counts. See below.
(2) 42 (6x). - Siberia (N), Far East (N). - Three reports.
Reports of tetraploids are mainly based on plants from East Chukotka where P. uniflora sensu Yurtsev should be rare but where the morphologically similar and proven tetraploid P. vulcanicola is common. A revision of the chromosome vouchers may show that P. uniflora is mainly or uniformly hexaploid.
Not included: Reports of 2n = 42 (6x) from the Yukon Territory and Alberta (Mulligan and Porsild 1969b, 1970, for P. ledebouriana; Packer and Whitkus 1982), where P. uniflora s. str. is unknown, whereas P. subgorodkovii is common and P. vulcanicola may be present. A report of 2n = 14 (2x) from South Chukotka (Zhukova and Petrovsky 1985b, two counts). The voucher plants should be checked.

Geography: Asian (N) - Asian Beringian: SIB RFE.

Notes: The modern Russian concept of Potentilla uniflora has been as a northeastern Asian species with its main range from Taimyr eastwards to the isthmus of the Chukchi Peninsula and as largely or entirely replaced by P. vulcanicola on the Chukchi Peninsula and in Alaska (Yurtsev in comment, partly revised from Yurtsev 1984b).

The name P. uniflora Ledeb. needs to be based on a lectotype. Ledebour (1815: 544) mentioned only "Davuria" in the protologue, i.e., the surroundings of Lake Baikal in southeastern Siberia. Eriksen commented that the type sheet is a mount of four elements from different localities.

Yurtsev: Potentilla uniflora was said to have been described from the Russian Far East: East Chukotka, ... ad sin. St. Lawrentii, leg. Eschscholtz (the first locality date was wrong: in Alps of Dahuria). I have spent several field seasons at St. Lawrence Bay where P. villosula is common on acid rocks and P. subvahliana on basic rocks but where [P. uniflora as Yurtsev considered it is absent]. The earlier collection which might have been available to Ledebour is Adams' collection from the lower reaches of the Lena River and Bykov Mys. These plants look like Ledebour's paratypes. Among essential characters are ternate leaves with upper surface dark green and with veins not very visible, margins somewhat revolute; lower surface veins softly pilose with hairs slightly flexuose, long, spreading, dense, white as is pubescence of petioles free of short wool (except for the uppermost part of them); leaflets cuneate, somewhat flabelliform with few long acute teeth; stipules along with epicalyx segments narrowly lanceolate, pilose, lacking wool; flowers 1-3 on each stem, large, with obcordate wide petals; and styles somewhat dilatated at the base with a few papillae. The main area where this species is common is dry mountainous tundras (mostly on acid rocks) from the Taimyr Peninsula up to the isthmus of the Chukchi Peninsula.

Elven and Murray: We have no idea why Yurtsev refers to a collection from the easternmost Chukchi Peninsula as the type, as Ledebour originally only mentioned "Davuria", ca. 4000 km farther southeast. If Yurtsev was right, and if any of the original material corresponds with any of the species present in the easternmost Chukchi Peninsula (Lavrentiya Bay, i.e., P. subvahliana, P. villosula, or P. vulcanicola), the name P. uniflora must be based on a type from that area, making it a priority name one for one of these three subsequently described species. Yurtsev's comment seems to be an attempt to justify a type (from the lower Lena River area in Yakutia) for the name P. uniflora fitting his concept of the species, rather than to respect the protologue. A type from Lavrentiya Bay material would be deplorable as there already are enough available names in this region, whereas the northern Siberian plant which for long has gone by the name P. uniflora then would be without a name. If admissible, a Yakutian type for this name would solve some problems. In spite of serious doubts, we provisionally accept P. uniflora in its northern and northeastern Siberian ("Yakutian") meaning. A very close study of the available type material is urgently needed.

In the "Yakutian" meaning, this is a major species of northern Asia from Taimyr-Putorana east to the westernmost parts of East Chukotka but not yet confidently confirmed from the Chukchi Peninsula or from the American side of the Bering Strait (the map in Yurtsev 1984b p. 190 is misleading). One northwestern Alaskan specimen (Ogotoruk Creek, ALA) conforms to the descriptions and keys of Yurtsev (1984b) and Soják (2004) but this is a single plant that may have been misinterpreted. We would like to see convincing population samples before we accept this species (whatever its name is going to be) from the Chukchi Peninsula and Alaska. All other material previously annotated as P. uniflora in America belongs to other species, mainly to P. vulcanicola, P. subvahliana, and the P. gorodkovii aggregate, partly also to P. villosula. As to non-Beringian Canada, Hultén's (1968a) record of P. uniflora from the western Hudson Bay is based on a specimen some years ago identified by Elven and Aiken as P. "vahliana" (it would probably be P. subvahliana today).