This section is from the book "Sub-Alpine Plants Or Flowers Of The Swiss Woods And Meadows", by H. Stuart Thompson. Also available from Amazon: Sub-Alpine Plants: Or, Flowers of the Swiss Woods and Meadows.
Petals 5, rarely 4, expanded. Stamens 10, rarely 8. Capsule 3-6 valved. Styles usually 3. Leaves nerveless, or 1-3 nerved. Seed with a mantle-like appendage at the base.
A small genus of about 15 species inhabiting Central and Southern Europe.
Stem fragile, prostrate, or ascending, branched, glabrous like whole plant. Leaves narrowly linear or acicular, acute, nerveless. Flowers in small, white, 1-3 flowered, or forked, loose cymes; flower-stalks elongated after flowering, and standing out horizontally. Calyx teeth 4, ovate-lanceolate, acute, 1-nerved, with membranous margins. Petals 4, longer than calyx. Stamens 8. Styles 2. Capsule 4-valved. Forming large, dense, evergreen patches on damp rocks, banks, and walls and in mossy, shady places of the mountain region up to 6500 feet at least. May to August.
Carpathians, Eastern, Central, and Western Alps; Pyrenees; Jura, Erzgebirge, Cevennes. Europe, from Spain to Servia.
A useful evergreen plant for filling up gaps in moist shady places in rock-gardens.
Stem 2-6 inches high, very brittle, prostrate, or ascending, branched, glabrous, like the whole plant, except for a few fine hairs on the leaves and flower-stalks. Leaves narrowly linear, rather flat, acute, or obtuse, nerveless, grass-green, somewhat wrinkled, short. Flowers in 1-2 flowered cymes; flower-stalks erect after flowering. Flowers pale white, a little larger than in muscosa. Calyx teeth 5, ovate-lanceolate, obtuse, 1-3 nerved, membranous at the margin. Petals 5, larger than calyx. Stamens 10. Styles 3. Capsule 6-lobed. More crowded in structure than the former species and with shorter leaves, but in cultivation it is said to merge into it.
Damp limestone debris in the Alps. July.
Eastern, Central, and Western Alps, Bavaria.
Stems elongated, tufted, 1-2 inches high. Leaves linear, obtuse, shortly mucronate, nerveless, fleshy, glabrous, sea-green, all cylindrical, or the upper ones flat on the upper side. Flower-stalks terminal, usually 2-flowered; flowers white, like those of the last species. Sepals ovate-lanceolate, obtuse, 3-nerved.
Steep rocks in the lower Alps, descending to the valleys. May.
These curious little silvery plants are mostly Mediterranean, but there are two species which attain a considerable height in the Pyrenees and the Alps of Savoy, Dauphiny, and Provence.
Stems spreading from a woody rootstock and forming a dense cushion of small, opposite, lanceolate, glabrous leaves, oval-acuminate stipules and lanceolate, acuminate, silvery bracts. Flowers very small, greenish.
Sandy and rocky places in siliceous mountains up to 7000 feet. June to September.
Western and Southern Alps; Pyrenees, Corsica, Asia Minor.
A small plant with woody, twisted rootstock, and ascending stems, which are densely leafy, pubescent. Leaves opposite, oval or lanceolate, obtuse, ciliate. Stipules lanceolate-acute, often longer than the leaves. Flowers in dense heads, silvery white, at the top of the branches. Bracts broad, obtuse or mucronate, scarious and silvery. Sepals equal, linear-obtuse, not membranous at the edges. Stamens 5.
Sandy, rocky places on hills and mountains; local. May to July.
Pyrenees, Western and Southern Alps (not in Switzerland). Southern Europe, Algeria.
Sometimes considered a variety of P. capitata Lamk., from which it differs by its rounded, obovate leaves and more prostrate habit. Its dense heads of silvery white bracts, which are large and broadly obovate, are very beautiful.
It flowers in June, and we have it from 5500 feet on Monte Toraggio in the Ligurian Alps, on which mountains it is not rare. It is a plant to introduce in hot, sandy places on the rockery.