Panarctic Flora

641027 Potentilla villosula Jurtz.

• Jurtz., Fl. Arct. URSS 9, 1: 319, 191 (1984). Holotype (LE): Russian Far East: East Chukotka, the Chukchi Peninsula, "sinus Emma", 13. July 1938, leg. B.N. Gorodkov.

2n= 28 (4x). - Far East (East Chukotka). - Zhukova (1965a); Zhukova and Petrovsky (1985b, four counts).

Geography: Amphi-Beringian: RFE ALA.

Notes: Yurtsev: Potentilla villosula is sympatric with P. vulcanicola and together with it prefers areas with maritime climate and acidic rocks. It is characterized compared with the others by higher, slender, and somewhat flexuose stems with few flowers; pedicels are shorter than the lower internodes, somewhat nutant; petioles in the upper 1/2-2/3 as well as prominent veins are covered with short wool (crispate hairs) and subadpressed, straight, non long verrucose hairs, later on dropping off, the veins becoming glabrate; the rosette leaves ternate; the cauline leaves of one ovate leaflet; the stipules ovate to ovate-oblongate, pilose, covered with loose wool; flowers not large, somewhat nodding; pistils at the base of styles sometimes with a few hairs. A hypothesis of hybrid origin of P. villosula from P. villosa x P. vulcanicola should be tested, but is not the only possible explanation.

Elven and Murray: Potentilla villosula is a major plant in the Bering Sea and Strait regions, in coastal, montane, and arctic tundras. On the Asian side, it is nearly confined to the Chukchi Peninsula. It is more widespread on the American side where it reaches northern Alaska and is common in coastal and alpine parts of south-central Alaska. The major parts of the range mapped by Hultén (1968a) for P. villosa belongs to P. villosula. Cody (1996) accepted the name P. villosula for plants in the southern and central Yukon Territory but this may be extending this species too far eastwards.

Soják (2004) implied P. villosula to have developed from crosses between P. villosa and P. vulcanicola. The affinity with P. villosa is supported by several morphological features, with P. vulcanicola especially by the frequent occurrence in P. villosula of apical hairs on pistils, in this group otherwise characteristic only of P. vulcanicola.