Colchicum alpinum
Colchicum alpinum, the alpine autumn crocus, is a corm-forming perennial with pale, delicate rosy-purple flowers, similar to C. autumnale but smaller. It is native to the Alps and the Appennini of Italy, Switzerland, France and Sicily, and cultivated as an ornamental in other regions.
Vegetative cycle and phenology
Colchicum alpinum emerges from underground corms—swollen storage organs up to about 40 × 30 mm—each late summer to produce flowers without any accompanying leaves. These flowers open in August, then wither and give way to capsules the following year. The flowers have four outer 30–50 mm long atop clothed in 4–6 leaves. In the spring after flowering, a rosette of leaves unfolds, and the previously formed fruits mature by early summer. This pattern of flowering in one year and fruiting in the next constitutes a biennial life cycle that distinguishes C. alpinum from its close relative, C. autumnale, which typically flowers and fruits within the same growing season.Under certain conditions—particularly at lower elevations or when grown in milder climates—some individuals may complete both flowering and fruiting in a single year, or even produce leaves concurrently with flowers. Transplant experiments have shown that extending the length of the growing season can shift C. alpinum towards an annual cycle more similar to C. autumnale, demonstrating the influence of environmental factors on its phenology.