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.
A genus of about 8 species inhabiting southern Europe, Western Asia, and N. Africa. Flowers very small, yellow, turning whiter. Silicule orbicular, edged, compressed, 1-celled, and 1-seeded.
Stem ascending, 3-6 inches long. Leaves grey, covered with stellate hairs, small, sessile, oblong spathulate. Flowers very small, yellow, then white, in a long spike. Silicules orbicular, flat, rather large (4 mm.), glabrous, on arched peduncles.
Sandy places and stony hills. Local. April, May.
Rhone Valley in Switzerland, Maritime Alps, Southern France, Mediterranean Europe, Corsica, Western Asia.
Stem leafy. Filaments of stamens short, furnished with a distinct tooth. Otherwise like Alyssum.
A biennial plant, grey, with stellate hairs, 1-2 feet high. Stem erect, generally branched above. Leaves sinuate-dentate. Fruit elliptic. Petals white, bifid.
Sandy roadsides in hot valleys. June.
Rare in Switzerland (Geneva, Martigny, Morges, etc.), North, East, and South-East Europe, Western Asia. Naturalised in a large part of France, and in England.
Small annuals or perennials, usually hairy or hoary, with spreading or tufted radical leaves, entire or toothed, with few or no stem-leaves. Flowers white or yellow. Filaments of the stamens without appendages. Pod oblong or elliptical, more or less flattened; the partition broad; the valves flat or convex. Seeds several in each cell. They mostly differ from Alyssum in their longer pod.
A considerable genus, ranging over the northern hemisphere, ascending to the highest elevations and to high Arctic latitudes; and extending along the great mountain chain of America into the southern hemisphere.
Stem erect, 1-4 inches high, simple, glabrous, leafless. Leaves in a radical rosette, linear or linear-lanceolate, acute, entire, ciliated, with long stiff .bristles, otherwise glabrous, shining. Flowers bright yellow. Petals slightly emarginate. Silicule oval, elliptical, or lanceolate, usually glabrous, surmounted by a long style.
Limestone rocks and debris, descending to stony places in the lower mountains and hills. May to August, according to altitude. Few plants have so wide a range of altitude. The writer has seen it at various heights from 2000 feet in Haute-Savoie to about 11,000 on the Diablons in Switzerland. In England it grows at sea-level in Glamorgan, where it was probably introduced.
Eastern, Central, and Western Alps, Carpathians, Var, Pyrenees, Corbieres, Cevennes, Jura.
The variety montana Koch, which is frequent in the Jura, is distinguished by its robust habit and its oblong head of golden yellow flowers, few in number.
The variety Hoppeana Reichb. (D. Zahlbruckneri Host.) is a small dwarf form found on the higher mountains. It has a style much shorter than the diameter of the silicule.