The Flora of Svalbard

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Life span

Perennial, but probably short-lived.

Growth form

Herb, either solitary or small tussocks with usually 1–3 erect or decumbent flowering stems, 3–5 (–10) cm tall. Flowering stems simple or branched once, as long as or slightly longer than the leaves. No runners. Stems and leaves with variable cover of white, villous, unicellular hairs.

Leaf

Leaves alternate. Basal leaves sheathing, with petiole 1–3 cm long; blades 0.5–1.5 × 1–1.5(–2.5) cm, about as broad as long or broader, pedate to palmate with 3 or 5 lobes, the mid lobe somewhat broader than the side lobes. Stem leaves sessile, palmatisect with 3(4–5) linear lobes.

Inflorescence

Single, terminal flowers.

Flower

Flower radially symmetric with five sepals and petals, 0.5–0.8 cm wide. Sepals ca 3 × 2 mm, ovate to obovate, with sparse to dense, white, villous hairs. Petals 1.8–3 × 1–2.3 mm, as long as or slightly longer than the sepals, oblong, yellow. Stamens 10–15, yellow, 1.5–2 mm long. Receptacle longer than broad, 4 × 2 mm, glabrous. Carpels numerous, free. Head of nutlets elongated, usually 4–6 × 4–5 mm.

Fruit

The fruits are nutlets, glabrous, and with short beaks about 0.1 mm long and curved about 90°.

Reproduction

No vegetative reproduction. Flowers regularly and regularly produces numerous mature nutlets, germinating to about 70 % (Alsos et al. in prep.)

Comparison

The two smallest species of Ranunculus in Svalbard – R. hyperboreus and R. pygmaeus – are often confused. They are easily distinguished by R. hyperboreus having three sepals and petals and a prostrate growth form with rooting shoots, whereas R. pygmaeus has five sepals and petals and grows as solitary plants with no rooting shoots. They also differ ecologically; R. hyperboreus is the perhaps only true aquatic vascular plant in Spitsbergen, whereas R. pygmaeus is confined to dry to occasionally moist ground.

Tall-grown plants of R. pygmaeus may be confused with small plants of R. nivalis, but the former has smaller flowers (0.5–0.8 vs. 1.5–2.2 cm wide), white willose hairs on sepals, and smaller heads (4–6 × 4–5 vs. 5–20 × 5–8 mm) with much smaller nutlets.

Habitat

Snowbeds, base of soil slopes, snow protected meadows, and depressions in heaths, base of bird cliff meadows. Mainly on well-drained and often coarse substrates (coarse sand to stones), but often moist or close to brooks. Indifferent as to soil reaction (pH) or perhaps slightly preferring circumneutral to acidic soils.

Distribution

Distributed in all zones and sections, and common except for the polar desert zone where it is more rare. Distributed on all major islands in the Spitsbergen group and also common on Bjørnøya.

Comments

Literature

Alsos, I.G., Müller, E. & Eidesen, P.B. In prep. Germinability of 87 arctic species stored in Svalbard Global Seed Vault.

Frøplante: Frø av denne arten er lagret i Svalbard globale frøhvelv, og deres spireevne vil bli sjekket med jevne mellomrom. (Alsos et al. In prep).

Ranunculus pygmaeus

	English name:
	German name:
	Norwegian name:	Dvergsoleie

Familiy:Ranunculaceae

Groupe:
Lifeform:
Worldwide distribution:
Distribution on Svalbard:
Diploid/Polyploid:
Chromosome number (2n):
Pollination vector:
Main mode of pollination:
Source: Brochmann, C. & Steen, S.W, 1999 - Sex and genes in the flora of Svalbard

Ranunculus pygmaeus Wahlenb.