Life span

Perennial, moderately long-lived.

Growth form

Solitary, often tussocky herb with short, vertical caudex branching at soil level. Caudex branches densely covered by broad, reddish brown, withered leaf sheaths, ending at ground level in leaf rosettes. Each leaf rosette potentially with several flowering stems, in a strict meaning lateral on the rosette but erect and appearing terminal. Flowering stems up to 20 cm long but usually much shorter.

Leaf

Leaves alternate, mostly basal, with petiole up to 5 cm, much longer than blade, and blade (0.6)0.9–2.0 × (0.8)1.0–2.2 cm, with three leaflets, all sessile. Petiole and both leaf surfaces pubescent with abundant hairs, 0.5–1.5 mm long, smooth or verrucose (a VERY strong lens needed), straight or slightly curly. Both leaf surfaces green. Lower leaf surface and veins with fairly dense hairs and numerous subsessile, yellow or red, minute glands. Upper leaf surface with sparse to moderately dense hairs. Leaflets oblong or obovate in outline, non-overlapping or contiguous, terminal leaflet (0.6)0.8–1.5 × (0.4)0.5–1.0 cm, lateral leaflets (0.4)0.6–1.2 × (0.3)0.4–0.8 cm, margins shallowly lobed with 3–5 pairs of subacute lobes or teeth along nearly the entire margin. Stem leaves reduced, with 2–3 small leaflets, densely hairy, usually with abundant red glands.

Inflorescence

Flowers single or 2–3 in a bracteates cyme. Bracts simple or dentate.

Flower

Pedicels (0.7)1.0–2.0(4.0) cm. Flowers radially symmetric with 5 epicalyx bractlets, sepals and petals. Hypanthium, epicalyx bractlets and sepals pubescent with fairly dense, long, white hairs and with abundant red glands. Epicalyx bractlets 4–7 × 1.5–3 mm, narrowly ovate or oblong, nearly as long as but much narrower than sepals, often deflexed in late flower stage and afterwards. Sepals 5–8 × 3–5 mm, triangular to broadly triangular. Petals 8–12 × 6–9 mm, ca 1.5 times as long as sepals, broadly obcordate, distinctly emarginate, bright yellow with an orange spot at base. Stamens numerous. Carpels numerous, free. Styles apical, 1.0–1.2 mm, tubular and very slender, without basal papillae.

Fruit

Fruit a nutlet, up to 20–30 or more from each flower.

Reproduction

Reproduction by seeds; no vegetative reproduction. The flowers are adapted to insect pollination. It is not known whether this species has sexual or asexual seed-set (i.e., agamospermy), or both. The plant flowers regularly from very early in the season, and mature fruits are produced regularly and shed well before the onset of autumn. Seeds germinate to ca. 40 % in an experiment (Alsos et al. 2013).

There is no special adaptation to dispersal. However, the nutlets are enclosed in a cup-shaped calyx and are only shed with strong winds or when the stems are touched by animals (i.e., ballistically).

Comparison

Potentilla hyparctica and P. crantzii differ from the other Potentilla in Svalbard by having leaves green on both surfaces; the others have leaves white on the lower surface due to dense pubescence, sometimes also on the upper surface (P. insularis, P. lyngei, P. pulchella). The main differences between P. hyparctica and P. crantzii are: In P. hyparctica flowering stems subterminal and erect, leaves always with only 3 leaflets,flowering stems one-flowered, and inflorescences with abundant and reddish glands; in P. crantzii flowering stems distinctly lateral and procumbent or ascending, leaves with 3–5 leaflets, flowering stems nearly always with several flowers, and inflorescences with sparse and yellowish glands.

Habitat

Dry or moist heaths, early snowbeds, herb slopes, river terraces and bars, tussocks in mires and wetlands, moist scree slopes, and bird manured sites. The substrate is fine (sand) or coarse and usually well-drained. Potentilla hyparctica is distinctly acidophilous and only rarely found in areas with calcareous bedrock or deposits.

Distribution

Distributed thoughout all zones and sections and common except for in the polar desert zone. Found on all major islands in the Spitsbergen group (Spitsbergen, Prins Karls Forland, Edgeøya, Barentsøya, Nordaustlandet) but not on Bjørnøya. It is more frequent in areas with substrates with circumneutral or acidic soil reaction (pH) than in areas with clearly basic ones, but as more acidic substrates occur intermittently throughout Svalbard, there are no large gaps in its distribution.

The general range is circumpolar and mainly in the arctic zones. In Europe, it occurs in Svalbard, northernmost Russia, and isolated in a minute area in the mountains of N Sweden. This range concerns ssp. hyparctica (see Comments).

Comments

Potentilla hyparctica belongs, together with P. crantzii, to section Aureae, whereas the other Svalbard species belong to sections Niveae and Pensylvanicae and assumed hybrid species between these two latter sections.

Three races (subspecies) have been described within P. hyparctica.  The Svalbard plants belong to the arctic circumpolar ssp. hyparctica (the species name is based on a plant from Ellesmere Island in NE Canada). The more tall-grown and southern ssp. elatior is distributed in S Greenland, N Canada and probably Alaska. In Siberia and the Russian Far East occurs a ssp. nivicola, perhaps transgressing the Bering Straits to Alaska. For differential characters between the subspecies and a discussion of these, see Elven in Aiken et al. (2007), Murray & Elven (2007), Elven et al. (2011), and Elven & Murray in Ertter et al. (2014).

Potentilla safronovae Jurtz. & Soják is assumed to be a hybrid species developed from P. hyparctica × pulchella. The name is based on a plant from N Siberia. Plants combining characters from those two species have been found here and there throughout the Arctic. We have seen plants from Baffin, Devon and Melville islands in arctic Canada, from Greenland, and at least one collection from Svalbard (Adventodden, 23. July 1896, E. Jørgensen, BG & O). The plants are usually easily recognized by a combination of leaves semi-digitate or semi-pinnate, i.e., with more than 3 leaflets and some small distance between pairs of leaflets, and leaflet lobes narrow (these two characters from P. pulchella), and large epicalyx bractlets and abundant red glands (these two characters from P. hyparctica). The question is whether this is widely distributed hybridogeneous species with an independent range or just single hybrid individuals or (agamospermic) clones in company with their parents.

Potentilla protea Soják is described as a hybrid species from P. crantzii × P. hyparctica, based on a type from N Greenland. Soják and Yurtsev have reported this hybrid species from Svalbard but we have not been able to confirm it based on identification of Svalbard specimens. The Svalbard material we have seen annotated as P. protea by Soják we rather interpret as P. hyparctica. We have, however, seen Greenland material combining the features of the two species.

Literature

Aiken, S.G. (ed.), Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H. & Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: descriptions, illustrations, identification, and information retrieval. – [CD-ROM version] National Research Council Canada, Ottawa.

Alsos, I.G., Müller, E. & Eidesen, P.B. 2013. Germinating seeds or bulbils in 87 of 113 tested Arctic species indicate potential for ex situ seed bank storage. – Polar Biology 36: 819–830. Doi 10.1007/s00300-013-1307-7.

Elven, R., Murray, D.F., Razzhivin, V. & Yurtsev, B.A. (eds.) 2011. Annotated Checklist of the Panarctic Flora (PAF).

Ertter, B., Elven, R., Reveal, J.L. & Murray, D.F. 2014 (2015). Potentilla Linnaeus. – In: Flora of North America Editorial Committee (eds.), Flora of North America north of Mexico. 9. Magnoliophyta: Picramniaceae to Rosaceae: 121–218.

Murray, D.F. & Elven, R. 2007. A new species and two new combinations in Potentilla sect. Niveae (Rosaceae). – Journal of the Botanical Research Institute of Texas 1: 811–814.