641043 Potentilla tikhomirovii Jurtz.
Distribution
Polar Ural - Novaya Zemlya: Rare
Taimyr - Severnaya Zemlya: Scattered
Anabar - Onenyo: Rare
West Chukotka: Frequent
Wrangel Island: Frequent
East Chukotka: Rare
Western Alaska: Rare
Northern Alaska - Yukon: Rare
Ellesmere Island: Rare
Eastern Greenland: Rare
Northern arctic Tundra: Presence uncertain
Mid Arctic Tundra: Rare
Southern Arcti Tundra: Rare
Shrub Tundra: Rare
Bordering boreal or alpine areas: Rare
- Jurtz., Fl. Arct. URSS 9, 1: 318, 184 (1984). Holotype (LE): Siberia: Taimyr, "in cursu inferiore fl. Jamu-Tarida (systema lacus Taimyrensis), ad ripam Jamu-Taridae", 07. July 1928, leg. A.I. Tolmatchev 187.
2n=
(1) 42 (6x). - Far East (West Chukotka). - Zhukova and Petrovsky (1985b, one count).
(2) 49 (7x). - Far East (West Chukotka). - Zhukova and Petrovsky (1985b, one count).
Geography: Circumpolar?: RUS SIB RFE ALA CAN GRL.
Notes: Potentilla tikhomirovii is assumed to be a hybrid species from crosses between P. arenosa subsp. arenosa and P. hyparctica.
Yurtsev: Potentilla tikhomirovii is recorded from many parts of the Asian and American Arctic (common in Wrangel Island). It reveals some diagnostic features of P. arenosa subsp. arenosa (lax wool on the lower surface of leaf blades; the lower layer of short straight and/or curved verrucose hairs on petioles of some leaves; styles are conical, viscid-glandulose at the bases) but deviates in many features toward P. hyparctica: the upper layer of pubescence on petioles is mainly of numerous hairs inclined toward the blade; on petioles, leaf veins, stems, and calyces there are numerous subsessile glands; the terminal leaflet often subsessile, with few teeth, flowers larger etc. Leaf blades in P. tikhomirovii are usually greenish canescent with loose pubescence; the type of wool is to be checked with SEM (preliminary data by Eriksen showed some diversity). But, in general, intersectional hybridization seems to be a normal phenomenon in Potentilla. The supposition of hybrid origin (as 'secondary hybrids') looks well grounded, though of course needs further testing.
Elven, Murray, and Aiken: Yurtsev reported P. tikhomirovii from very scattered localities from the northern Urals east to northeastern Canada and it is present in at least northeastern Greenland. See also P. nubilans above. Potentilla tikhomirovii is either a set of agamic hybrid biotypes, cropping up here and there and with some local spread, or a hybrid species with a very polytopic origin. The material from northwestern North America (ALA) consists of a series of scattered plants from western and northern Alaska and one more extensive population group in the central parts of the northern Brooks Range. Much material is available from Ellesmere Island (northeastern Canada) where it obviously forms significant populations. The northeastern Greenland population group probably also has a range. It indicates occasional hybridization and well established biotypes in at least three regions in addition to Russia. It is still problematic for us to fully accept these scattered biotypes as one consistent hybrid species.
Another matter is that if P. nubilans and P. tikhomirovii both are results from hybrids between P. arenosa (two subspecies) and P. hyparctica, they should perhaps rather be considered one species with two subspecies (for each parental subspecies of P. arenosa).
Higher Taxa
- Potentilla [6410,genus]