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Saxifraga aizoides L. coll.

Place: Blomstrandhalvøya

Place: Ossian Sarsfjellet

Place: Bockfjorden

Life span

Perennial, probably long-lived due to vegetative growth.

Growth form

Herb with short subterranean rhizome, extensively branched at or below ground level, densely to laxly caespitose with stems procumbent at base, erect above. Erect parts of stems 2–10 cm, glabrous in lower part, with very short, stout, white hairs in upper part.

Leaf

Leaves alternating. Basal and stem leaves equal, numerous, not sheathing, semi-perennial (staying green over winter but withering during the second summer), retained for several years after withering. Leaves 6–10 × 1.5–2.5 mm, thick, narrowly oblong, subacute, entire or with a few, short teeth, without sheathing petiole, glabrous.

Inflorescence

Flowers terminal on stem, singly or more rarely 2–3 in a short cyme.

Flower

Flowers radially symmetric with five sepals and petals. Sepals 2.5–3.5 × 1.5–2.2 mm, ovate to broadly ovate, obtuse, yellowish green, appressed or spreading in both flower and fruit stage. Petals 3.5–6 × 1.5–2.2 mm, narrowly oblong or ovate, obtuse, non-overlapping, bright yellow. Stamens 10. Ovary semi-inferior, of two carpels, split apically.

Fruit

Fruit a capsule. Seeds numerous.

Reproduction

Very restricted vegetative growth, forming small colonies and mats due to branched rhizome and procumbent lower parts of stems. Efficient reproduction by seeds alone. Flowering late in the season, in some sites intermittently, and no ripe seeds were found in 2008 (Alsos et al. in prep.). Flowers adapted to insect pollination, but according to studies from other regions, selfing may be common (Brochmann et al. 1999). Capsules have apical opening which ensures that the seeds only are dispersed at a minimum wind speed. Seed dispersal is often after the first snow fall, which increases the dispersal distance as the seeds are blown across a smooth surface (Savile 1972). Seeds are also dispersal by animals, e.g. geese, that selectively feed on seed capsules (Prop et al. 1984). Secondary dispersal by water or wind.

Comparison

The three yellow-flowered Saxifragas of Svalbard are rather different. Saxifraga platysepala is distinguished from the two others by its long, above-ground runners (stolons) ending in small rosettes (the "Spider Saxifrage") and by being glandular pubescent. Saxifraga hirculus and S. aizoides are separable by entire vs. ciliate leaves, by large and mostly single flowers per stem vs. small and often several ones, and by sepals deflexed in late flower and fruit stages vs. appressed or patent.

Habitat

Most frequent on gravel and sand periodically inundated from lakes, rivers, or brooks and on gravel slopes with seepage. Prefers well-drained to coarse substrates. Perhaps restricted to substrates (and water) with a circumneutral to basic reaction with pH 6.5 or higher (Elvebakk 1982).

Distribution

Frequent in the middle arctic tundra zone, less frequent in the northern arctic tundra zone. Present in all sections. Restricted to Spitsbergen, Prins Karls Forland, and Bjørnøya, and predominantly in areas with neutral to basic bedrock.

Comments

Saxifraga aizoides is morpohologically uniform in Svalbard, whereas it is polymorphic, at least in flower colour, in mainland N Europe. The petals of mainland plants vary between bright yellow (with or without darker dots), reddish yellow with red dots, and purple, with associated darker coloration of fruits, stamens, and sepals. The Svalbard plants have uniformly bright yellow petals without prominent darker dots. The flowers are also uniformly smaller than in mainland plants, with shorter (and thereby relatively broader) sepals and petals, and with shorter, subentire leaves. The mainland morphs are widely distributed in Europe, whereas the Svalbard morph is the one also found in Greenland, arctic Canada, Alaska, and arctic NE Asia. No investigation of this variation has been undertaken.

Literature

Brochmann, C. & Steen, S.W. 1999. Sex and genes in the flora of Svalbard - implications for conservation biology and climate change. – Det Norske Videnskaps-Akademi. I. Matematisk Naturvitenskapelig Klasse, Skrifter, Ny serie 38: 33−72.

Elvebakk, A. 1982. Geological preferences among Svalbard plants. – Inter-Nord: 11−31.

Prop, J., van Erden, M.R. & Drent, R.H. 1984. Reproductive success of Barnacle Goose Branta leucopsis in relation to food exploitation on the breeding grounds, western Spitsbergen. – Norsk Polarinstitutt Skrifter 181: 87−117.

Savile, D.B.O. 1972. Arctic adaptations in plants. – Canada Department of Agriculture Research Branch Monograph 6. 81 pp.

 

Scientific name, meaning and origin:

Saxifraga: From latin saxum, mountain knoll, and frango, breaking. Plantename by Marcellus Empiricus, app. 410.

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Saxifraga aizoides

English name:Yellow Saxifrage
German name:Fetthennen-Steinbrech
Norwegian name:Gulsildre
Familiy:Saxifragaceae

Scientific data:


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