Solitary herb with a central root, the main stem a stout, woody, unbranched or branched caudex at ground level, branches densely covered with reddish brown remains of stipules and petioles. Most leaves basal. One or usually several lateral, ascending flowering branches up to 15(20) cm.
Leaves alternate. Basal leaves up to 8(12) cm long. Petioles up to 7 cm, densely pubescent with long, subappressed white hairs, strongly verrucose (VERY strong lens or microscope). Stipules lanceolate, acute, adnate to petiole. Blades 3.5–4.5(5.0) × 1.5–2.5(3.0) cm, obovate in outline (with the apical and the upper pair of lateral leaflets larger than the others), pinnate, greyish green on upper surface, grey to white on lower surface (due to difference in density of hairs), with white, soft, silky hairs. Hairs distinctly verrucose. Leaflets (5)7 in 2–3 pairs at a distinct distance from each other and decreasing markedly in size downwards on the blade, oblong in outline, terminal leaflet 1.2–2.0(2.8) × 0.7–1.2(1.5) cm, upper lateral leaflets 1.0–1.5(2.0) × 0.6–1.0(1.2) cm. Each leaflet divided 50–60 % towards mid vein with (3)4–6 lobes per side, lobes linear or narrowly oblong, subacute, with flat or slightly revolute margin and mostly with hair points at lobe ends.
Inflorescence an apical cyme with (1)2–4 flowers.
Pedicels straight, 2–4 cm in flowering stage, not elongating much in fruiting stage, without or nearly without glands. Flowers radially symmetric, moderately large, 1.5–1.8 cm in diameter, with 5 epicalyx bractlets, sepals and petals. Hypanthium, epicalyx bractlets and sepals with dense, straight hairs and numerous minute, sessile, yellow glands. Epicalyx bractlets 3.5–4.5 × 0.6–1.0 mm, shorter than sepals, linear or narrowly elliptic, obtuse or subacute. Sepals 4–6 × 1.8–2.2 mm, narrowly triangular, obtuse or subacute. Petals 6–9 × 6–9 mm, ca 1.5 times as long as sepals, obcordate, distinctly notched, more or less overlapping, yellow. Stamens ca. 20. Carpels free, ca. 30–50; styles apical, narrowly cylindrical with several fairly small papillae at base.
Fruit a nutlet, often 30–40 per flower.
Reproduction by seeds, sexual or asexual (agamospermy) or both; no vegetative reproduction. The comparatively large flowers are potentially insect pollinated. The reproduction is assumed to be sexual but could also be partly or predominantly asexual (agamospermy). There is, however, a need for pollination also in asexual plants as it is necessary for development of endosperm and seed (pseudogamy). Fruit production seems to be regular.
There are no special adaptations to dispersal but the local spread of the nutlets is most probably facilitated by wind (ballistic).
Potentilla lyngei and P. pulchella are distinguished from the other species of Potentilla in Svalbard by having pinnate leaves (the others have ternate or semi-digitate leaves, i.e., with 3–5 leaflets attached at the same or nearly the same point). Potentilla lyngei and P. pulchella differ in the following characters: In P. lyngei the pedicel is long (> 2 cm), the flowers are large (> 1.5 cm in diameter), the petals are large and as broad as long (6–9 × 6–9 mm), and the leaflets have broader and less deeply dissected lobes; in P. pulchella the pedicel is rarely 2 cm, the flowers are smaller (< 1.5 mm in diameter), the petals are smaller and only half as broad as long (4–5 × 2–3 mm), and the leaflets have narrower and more deeply dissected lobes. The complex currently denoted as P. insularis may be similar to P. pulchella and P. lyngei in pubescence of leaves but differs in having semi-digitate leaves.
Only known with certainty from a large, southwest-facing scree slope on calcareous bedrock, dry and unstable, but one of the warmest places in Svalbard in sunny weather. The substrate is a mixture of gravel and stones.
Thermophilous. The single certainly known locality is on the slope of the mountain Templet (Bünsow Land) at the innermost part of Isfjorden, in the middle arctic tundra zone and the weakly continental section.
Outside Svalbard, this species is only known from Novaya Zemlya (from where it was first described, with a name honouring the Norwegian botanist Bernt Lynge who made an important contribution to our knowledge of these islands during an expedition in 1921) and one site on Rybachi Peninsula in the Murman area, close to the Norwegian border in Finnmark. We have not been able to confirm reports from Greenland (Yurtsev in Elven et al. 2011, based on information from J. Soják).
There has been a long discussion whether Potentilla lyngei is present in Svalbard or not, and whether it can be parental in the evolution of the Svalbard endemic P. insularis (see Elven et al. 2011). Yurtsev and Soják based their Svalbard record of P. lyngei on a single collection from Mt. Gipshuken (Bünsow Land), of leaves and stems mounted separately on a sheet. Hamre (2000) identified this material as P. insularis; however, in our opinion the stems could belong to either P. insularis or P. arenosa ssp. chamissonis, whereas the leaves could belong to P. pulchella or possibly P. lyngei. This mountain has been visited at least two times since, with this plant in mind, and has been extensively investigated, most recently by R. Elven, E. Hamre, K.T. Hansen, J. Nyléhn, and T. Engelskjøn in the 1990s, and only P. insularis, P. nivea, P. pulchella, and the less related P. hyparctica have been found there. Populations from this locality of the three former species were included in the molecular investigations of Svalbard Potentilla (Hamre 2000; Hansen 2000; Nyléhn & Hamre 2002). There is currently little support for P. lyngei being present at Mt. Gipshuken.
However, a plant resembling the very distinctive Novaya Zemlya and Rybachi Peninsula P. lyngei has recently (2010) been identified in material collected in the 1980s from the nearby Mt. Templet, together with a very polymorphic population connecting it through P. insularis to P. arenosa ssp. chamissonis. We assign this plant to P. lyngei but it may represent an independent species.
Yurtsev (in Elven et al. 2011) stated: "Potentilla lyngei may be closely related to P. anachoretica [a rare, amphi-Beringian species] but differs in a number of characters including the shape and dissection of leaf blades and their segments, less dense pubescence of leaf lower side (the straight hairs on it smooth), wider and shorter epicalyx bractlets, and by growing in less dry sites ... As to the relations between P. insularis and P. lyngei, one needs to examine in detail the former species because P. pulchella, which was compared [in RAPDs, isoenzymes, and morphology] to P. insularis as a representative of sect. Multifidae [= Pensylvanicae] stands rather separate in the system of the section. Without such analysis I do not agree to transfer P. insularis into other section from Multifidae to which it belongs by diagnostic features."
Elven, R., Murray, D.F., Razzhivin, V. & Yurtsev, B.A. (eds.) 2011. Annotated Checklist of the Panarctic Flora (PAF) Vascular plants. http://panarcticflora.org/
Hamre, E. 2000. Variation in the genus Potentilla in Svalbard – Analysis of isozymes, micro– and macromorphometry. – Cand. scient. Thesis, Univ. Oslo, Oslo.
Hansen, K.T., Elven, R. & Brochmann, C. 2000. Molecules and morphology in concert: tests of some hypothesis in arctic Potentilla (Rosaceae). – American Journal of Botany 87: 1466–1479.
Nyléhn, J. & Hamre, E. 2002. Facultative apomixis and hybridisation in arctic Potentilla section Niveae (Rosaceae), contributions to an intricate taxonomy. – In: Nyléhn's Dr. scient. Thesis, Univ. Oslo, Oslo.