Saxifraga oppositifolia
A creeping, mat-forming plant that covers itself with purple-pink star flowers as soon as the snow melts. It grows on rocks, scree and windy ridges, and climbs higher than any other flowering plant in Europe: it has been found in bloom at 4505 m, just below the summit of the Dom. Its tiny opposite leaves, packed along the stems, gave it its Latin name.
On a ridge still patched with snow, a green mat so low it could be mistaken for moss has covered itself with purple flowers: this is the purple saxifrage.
According to Info Flora, its creeping stems, 10 to 30 cm long, form dense, flattened tufts. Its tiny leaves, 2.5 to 4 mm long, grow in pairs facing each other, packed along the stems: they gave the species its Latin name. Fringed with cilia, they bear one to three pores at the tip, through which the plant can get rid of lime. Its flowering shoots, upright and 1 to 5 cm long, only ever carry one flower, violet-pink to purple, whose petals extend well beyond the sepals.
It is found in scree and stony ground, from the subalpine to the alpine zone, in the Alps and the Prealps; Info Flora links it in particular to high-altitude limestone scree, and describes it as an arctic-alpine plant. It holds a record: in August 2009, Christian Körner, a botanist at the University of Basel, found cushions of it, one of them in full bloom, at 4505 m, some forty metres below the summit of the Dom, above Saas-Fee. No flowering plant had ever been seen so high in Europe.
A perennial, it keeps its leafy shoots above ground from one year to the next. On the Dom, according to Christian Körner’s measurements, the whole plant, roots included, drops below 0 °C every night, even at the height of summer, and some 600 hours a year above 3 °C are enough for it. The magazine Spektrum adds that it can withstand a bath in liquid nitrogen. Up there, its cushions are thought to produce hardly any seeds able to germinate: it was probably the wind that carried seeds up from lower down.
The Red List does not consider it threatened in the Alps, but classes it as critically endangered in the Jura. Only a few cantons protect it. On the Swiss Plateau, it has disappeared along with a distinct form, the Lake Constance saxifrage. According to a conservation factsheet from 1999, this relic of the ice ages had adapted to the Thurgau shores of the lake, at around 400 m, which the water covered for several weeks a year. Smothered by algae that flourished as the lake grew richer in nutrients, it was not seen again in Switzerland after 1956, nor anywhere else after 1965.
Sources: Info Flora, species accounts for the species and the type subspecies; Swiss Agency for the Environment, Forests and Landscape, Swiss Commission for the Conservation of Wild Plants, Swiss Floristic Network Centre and Pro Natura, conservation practice sheet “Saxifraga oppositifolia subsp. amphibia” (1999); swissinfo.ch, “Scientist finds flower growing above 4,500m” (2011); Spektrum der Wissenschaft, “Die höchste Blütenpflanze Europas” (2011).
