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.
Perennial herbs, with bulbous, tuberous, or shortly creeping rootstock, frequently ensiform leaves and regular flowers with 2 bracts. Perianth 6-lobed. Stamens 3. Style simple. Stigmas often dilated. Fruit a 3-celled capsule.
About 100 species. Europe, temperate Asia, Africa, and America.
This includes C. vernus All., which some botanists have considered a separate species.
Corm covered with dry membranous scales, scape enveloped in a sheath. Leaves grass-like, recurved at margin. Stigmas orange, shorter than the perianth segments. Perianth 6-lobed. Flowers opening before or with the leaves, immediately the snow begins to disappear, white or violet, the white form having a yellowish tube.
Eastern, Central, and Western Alps, Jura, Cevennes, Pyrenees, Carpathians, Balkans; often naturalised in the plains and in England.
Iris L. Seven species of Iris (virescens, germanica, sambucina, squalens, graminea, Pseudacorus, and sibirica) may be found either native or sub-spontaneous in Switzerland, but none of them reach the sub-alpine region.