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 3-4 inches high, erect. Rosette leaves linear-lanceolate, narrow, obtuse, or shortly acuminate, 3-5 times as long as broad, soft and shiny. Calyx-lobes spreading, acute, and contracted at the base, the sinus between the calyx-lobes being broad. Corolla-lobes acute. Flowers solitary, very large.
Limestone Alpine pastures; rare. May to July.
Central and Western Alps; rare in Switzerland. Jura, Cevennes, Pyrenees.
Stem erect, simple, few-leaved, 1-flowered, 1-4 inches high. Leaves ovate, elliptical or lanceolate, acute, the lowest in rosettes, the upper 1 or 2 pairs distant. Corolla saucer-shaped, 5-cleft, throat white. Flowers light or dark azure-blue, varying considerably, and occasionally mauve or white. In Flemwell's Flower Fields of Alpine Switzerland (1911) is a beautiful and unique picture showing all these varieties of colour.1

Plate XXVI.
1. GENTIANA ASCLEPIADEA (WITH WHITE VARIETY).
2. G. VERNA (IN FOUR COLOUR FORMS).
3. G. CILIATA.
4/7 NATURAL SIZE.
Meadows and pastures from the plains to at least 10,000 feet in the Alps; often abundant and in large clusters in the sub-alpine zone and above. April to July.
1 These colour forms are also shown in Plate XXVI.
Carpathians, Alps, Erzgebirge, Jura, Black Forest, Pyrenees, Caucasus, Central and Southern Europe, Western and Northern Asia; rare in British Isles.
Stem erect, simple, leafy, 2-5 inches high, 1-flowered. Leaves obovate or nearly spathulate, obtuse, slightly 3-nerved, crowded except sometimes the uppermost; imbricate in the young shoots. Corolla saucer-shaped, 5-cleft, handsome, deep azure-blue, or very rarely violet.1 Lobes not fringed. Throat naked. Style deeply 5-cleft.
Damp pastures, perferably on the higher calcareous Alps; local, but often in great masses; 5000-8500 feet. June to September.
Bavaria, Eastern, Central, and Western Alps, Abruzzes.
Stem ascending from a creeping base, 2-4 inches high, densely leafy. Leaves small, linear-lanceolate, mucronate, rough at the edges. Flowers a rich violet, solitary, shortly peduncled. Corolla-lobes 10, unequal, 5 of which are oval, obtuse, and 5 are smaller and toothed. Capsule elliptical.
Damp pastures and banks of rivulets in the mountains at about 4000 to 6000 feet, but extending rarely to 9000 feet. June, July.
Eastern Pyrenees, Central Pyrenees (rare), Spain, Ariege, Aude; Carpathians, Armenia, Caucasus. Not known in the Alps.
Annual. Stem 1-6 inches high, erect, leafy, rather fragile; usually cymosely branched and many-flowered, less often simple and i-flowered. Leaves 3-5 nerved; root-leaves ovate, in rosettes; stem-leaves lanceolate. Calyx cylindrical, with 5 prominent angles and acute teeth. Corolla rotate, with a cylindrical tube, naked throat and acuminate, unfringed teeth. Flowers small, blue, or sometimes mauve, very rarely white, only opening in sunshine.
Alpine meadows and pastures 5000-10,000 feet. June to September.
Eastern, Central, and Western Alps, Jura, Pyrenees, Carpathians, Servia, Bulgaria, Montenegro, Turkey, Iceland, Scotland (rare), Central and Arctic Europe (Iceland), Asia Minor, North America, Greenland.
1 Found by the writer with violet flowers near Bovine (Col de la Forclaz), June, 1908. This was the first record.
 
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