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.
Stem erect or ascending, obtusely angled, glabrous or with a few scattered hairs like the leaves, leafy below, 1-flowered. Leaves crenate; root-leaves and lower stem-leaves ovate or elliptical, shortly stalked, longer than the leaf-stalk; median stem-leaves narrower, acute, sessile; uppermost lanceolate, small. Corolla terminal, bell-shaped, large, dark violet-blue. Calyx-teeth linear, one-third length of corolla.
Pastures, woods, bushy and stony places in the calcareous Alps; 4000-6500 feet.
Easily grown in an open, sunny spot, but is apt to die off in winter.
Segments of corolla incised at the base, and separated by a rounded sinus. Calyx-teeth reflexed. Rootstock slender, rampant; stem ascending; leaves lanceolate or linear-lanceolate, occasionally toothed or with cilia. Flowers blue, 1-3.
Granitic Alps; local and rare; 6500-9000 feet.
Switzerland (S. Tessin and Valais, above the Valley of Minister, at Berisal, and between Saas and Binn), Aosta Valley in Piedmont.
Grows rapidly in gritty loam, but hates lime. Sometimes a little peat will improve the growth.
A tall spiky species with usually simple stem, which is very leafy and almost tomentose. Leaves green, downy beneath; lower leaves shortly petioled, cordate; upper ones sessile and becoming narrower and narrower. Flowers small, blue-violet, very shortly stalked, in clusters at the junction of the bracts and stem and forming a long spike. Sepals linear-lanceolate, spreading. Capsule pendent.
Mountain woods in the sub-Alps; very local. June, July. A frequent plant in the Chestnut zone of the Italian Maritime Alps.
Southern Switzerland; Western, Central (?), and Eastern Alps, Caucasus, Siberia.
Stem erect, slender, leafy above, 1-1 1/2 feet high. Raceme more or less unilateral, 3-5 flowered. Leaves all sessile, ovate-lanceolate, dentate, glabrous or slightly hairy. Flowers blue, pendent. Calyx-teeth linear or subulate, two-thirds length of corolla.
Meadows, borders of woods in the Alps and sub-Alps; abundant and often in great masses. June to August.
Carpathians, Eastern, Central, and Western Alps, Jura, Pyrenees, Spain.
Erect stems, 1-3 feet high. Lower leaves heart-shaped, on long stalks; upper ones small, ovate-lanceolate. Flowers drooping, blue, varying in size, single in the axils of the leaves, and forming long, terminal, simple and more or less unilateral racemes. Capsules nearly globular. Calyx-lobes narrow-lanceolate.
Open woods, borders of roads, etc., from the plains to at least 5000 feet. June, July.
Most of Europe, except the Mediterranean region, Caucasus, Asia Minor. British.
Very variable, sometimes approaching smaller specimens of C. latifolia, and sometimes with the upper flowers clustered to resemble C. glomerata. Lower leaves broadly heart-shaped, on long stalks, coarsely toothed; upper ones small, ovate-lanceolate. Flowers large, 2 or 3 together in short, leafy racemes, or sometimes solitary. Calyx-teeth broadly lanceolate, hairy.
Woods, ravines, and roadsides from the plains to the lower Alps. June to September.
Europe, Western Asia, and right across Siberia, N. Africa. But most common in Western Europe. British.
The tallest and most handsome species, often in England 3-4 feet high, usually shorter in Switzerland. The stems are rarely branched, though leafy. Leaves ovate-lanceolate, acuminate, narrow at the base and lower ones stalked, pubescent, coarsely biserrate. Calyx-teeth lanceolate. Flowers large, blue, deeply cleft into 5 lanceolate, acute lobes.
Woods, ravines, by streams in the plains and sub-alpine region; rare in Switzerland. July, August.
Alps, Pyrenees, Vosges, Jura; woods of Northern Europe, Northern and Central Asia to the Arctic regions, but becoming a mountain plant in Southern Europe. Occasional in England and Scotland.