Mat-forming herb with extensively system (subterranean or floating) of branched stems (rhizomes), thick, white, usually embedded in peat or mud, rooting at the nodes, and with erect leaves, 5–13 cm tall, and flowers from the nodes. Lateral shoots developing from axial buds within the leaf sheaths. Stems and leaves glabrous.
Leaves alternate. Petioles usually (2)5–6(10) cm long and 1–2(3) mm broad. Blades 1.5–2(3) × 1.5–2(3) cm, oblate to obovate in outline, dissected for (50)60–80 % of their length, and lateral lobes may be dissected again. Lateral lobes diverging at ca. 30–60°.
Single terminal flowers on pedicels 4–8 cm long, mostly longer than the leaves.
Flower radially symmetric, 1.5–2 cm wide, with 3 ‘sepals’ and 5–6 ‘petals’. ‘Sepals’ ovate, 6–9 × 4–5 mm, shorter than ‘petals’, not deflexed, outer surface purple and inner surface pale yellow. ‘Petals’ 8–11 × 4 mm, narrowly obovate with an uneven apex, pale yellow. Stamens numerous (>10), ca. 2 mm, with yellow anthers and greenish yellow filaments. Carpels numerous, free, yellowish green or purple.
Fruits are not developed.
A triploid hybrid where no seed reproduction is known; however, efficient local vegetative reproduction by rhizome results in extensive stands (clones). Pollen is of poor quality and no ripe fruits have been observed.
All dispersal is probably by shoot fragments carried by animals e.g. geese or reindeer.
The species of the genus Coptidium differ from those of the genus Ranunculus in several features, the most evident being the thick, white, underground or under-water stems and the leaves and flowers arising mostly singly above ground from these stems. There is nothing similar in Ranunculus. Another difference is the fragrant flowers of Coptidium (no fragrance in Ranunculus). Less visible is the corky floating tissue in the fruits of Coptidium, absent in Ranunculus.
Coptidium pallasii and C. spitsbergense are both aquatic and have similar growth form. Flowering plants are easily distinguished as C. spitsbergense has comparatively small, pale yellow flowers, whereas C. pallasii has white and much larger flowers. Non-flowering plants are distinguished by the blade: In C. spitsbergense the blade is dissected for more than 50 % and the lateral lobes often dissected again; in C. pallasii the blade is entire or dissected for usually less than 50 % of its length into one broad mid lobe and 1–2 smaller lateral lobes reaching about 2/3 the length of the mid lobe.
Helophyte or hydrophyte. Growing in wet moss tundra, in wet moss mats, within shallow ponds or in their margins or in very wet marshes. Most stands are found on slightly acidic to slightly basic substrates.
In the middle and northern arctic tundra zones and in the weakly continental and transitional sections. This is the most widespread of the Coptidium taxa in Svalbard, in Spitsbergen known from Sørkapp Land, the central parts around Van Mijenfjorden and Isfjorden, and Agardhbukta on the east coast. In addition, it is recorded from N Prins Karls Forland and from W Edgeøya.
The general range is not well known but may be interrupted circumpolar, see Comments.
Coptidium spitsbergense is probably a seed and pollen sterile triploid hybrid between C. pallasii and C. lapponicum (Elven et al. 2011). In Svalbard, it occurs in large stands and nearly always in the absence of one (C. pallasii) or both assumed parents. It is rather common compared to C. pallasii, which is only found at 8 locations, and also more frequent than its other assumed parent, C. lapponicum. Due to its frequency and its independent presence in many sites, it is obviously not a case of occasional hybridization. Its range is assumed to be mainly or entirely due to animal dispersal of shoot fragments.
Both the total range and the name of this plant have been discussed. Tolmachev (1971) made the identification with Ruprecht's var. minimus, thereby accepting the species also outside Svalbard. Furthermore, it is now confirmed from the island Kolguev and several other Russian regions and from both central and eastern parts of arctic Canada (Cody et al. 1988). A survey of material (ALA, CAN) in 2009 revealed no specimens from Alaska or Yukon.
Two name forms have been applied: "spitsbergensis" ("spitzbergensis") and "spetsbergensis". When Hadač in 1942 published his name Ranunculus spitsbergensis, he did it with designation of a separate type and did not base it on Nathorst's name from 1883, var. spetsbergensis. Jalas (1988) showed that Nathorst's name, spelling and type have priority at varietal level, whereas Hadač' name, spelling and type have priority at species level.
Cody, W.J., Blondeau, M. & Cayouette, J. 1988. Ranunculus x spitsbergensis (Nath.) Hadac, an addition to the flora of North America. – Rhodora 90: 27–36.
Elven, R., Murray, D.F., Razzhivin, V. & Yurtsev, B.A. (eds.) 2011. Annotated Checklist of the Panarctic Flora (PAF) Vascular plants. http://panarcticflora.org/
Jalas, J. 1988. Atlas florae europaeae notes, 9–11. – Annales Botanici Fennici 25: 295–299.