The Flora of Svalbard

No means of vegetative reproduction. Sexual reproduction by seeds. Flowering period prolonged, from late June to August. The nearly closed flower with only slightly emerging petals, and fully enclosed stamens, suggests a high level of self pollination in this species and subspecies, even if its relatives (e.g., Silene involucrata) are much more adapted to insect pollination. A high number of seeds are produced, a sign of self pollination. Nevertheless, a few hybrids with S. involucrata are reported from Svalbard, sure signs that some cross fertilization takes place. The seeds mature regularly, and they germinate to 30–100 % at 18–20ºC, and about 5 % under outdoor conditions (Alsos et al. in prep., Müller et al. 2011). Seed weight is 0.008 g/50 seeds (Alsos et al. in prep.). The seeds have wings and therefore adapted to wind dispersal along the ground. The stems become very stiff in autumn. The combination of stiff stem, erect capsule, and apical capsule teeth assure that dispersal only takes place when the wind speed is above a certain level (or when moved by an animal) assuring initial spread of seeds at some distance from the mother plant.

The only plant similar to Silene uralensis in Svalbard is S. involucrata. When in flower, they differ in colour, shape, and emergence of petals (lilac, fringed, and short emergent in S. uralensis; white, more regular, and long emergent in S. involucrata) and also in flowers nodding in S. uralensis, erect in S. involucrata (but the flowers in S. uralensis rapidly becomes erect after pollination has taken place). The calyx in S. uralensis is larger than that in S. involucrata both in flower stage (12−15 × 7−12 mm vs. 9−13 × 4−10 mm) and especially in fruit stage. Even if both species have abundant glandular hairs, S. involucrata is much more sticky than S. uralensis. Dust and dirt fragments are often attached to the stems and leaves of S. involucrata, rarely to those of S. uralensis.

Not thermophious. Most common in moderately moist heaths and meadows, shallow mires, along watercourses, and in moderate snowbeds. On moderately drained, mixed or fine textured soils with weakly acidic or basic soil reaction. Requires a minimum of snow protection during winter, but young individuals often found on quite exposed sites. Inflorescence and stem probably grazed by reindeer. 

Elven et al. (2011) argue that there are disjunct morphological differences between the arctic circumpolar Silene uralensis ssp. arctica, the Scandinavian S. wahlbergella, and the boreal to arctic, nearly circumpolar S. uralensis ssp. uralensis. The ranges of S. uralensis ssp. arctica and S. wahlbergella do not overlap (they are allopatric), and no morphological transition is known. The ranges of ssp. arctica and ssp. uralensis do, however, overlap in several regions (they are parapatric), at least in the northernmost Urals and Vaigach island, in arctic Canada, and in Greenland. Even here, the two plants appear as morphologically distinct, a few times in mixed stands. Taxonomic rank may therefore be debatable, as subspecies (due to morphological similarity and parapatric ranges) or as species (due to discontinuous morphological differences in spite of overlap). Lack of transitional plants or populations may, however, partly be due to the assumed predominant self-fertilization.

Some authors have argued that ssp. arctica only occurs in Svalbard, whereas the arctic plants elsewhere belong to ssp. uralensis (e.g., Bocquet 1967). We have compared plants from Svalbard with specimens from Greenland, Canada, Alaska, and Russia and find no differences whatsoever.

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

Bocquet, G. 1967. Physolychnidium olim Gastrolychnidium nomenclaturae fundamentum includens combinationes taxaque nova nonnulla Silenes generis. – Candollea 22: 1–38.

Elven, R., Murray, D.F., Razzhivin, V. & Yurtsev, B.A. 2011. Annotated Checklist of the Panarctic Flora (PAF). – Oslo: CAFF/University of Oslo.

Müller, E., Cooper, E.J. & Alsos, I.G. 2011. Germinability of arctic plants is high in perceived optimal conditions, but low in the field. – Botany 89: 337-348.