Colchicum speciosum is a perennial herbaceous plant with a peculiar development cycle. It blooms in late autumn (September–October). The following spring, leaves and fruits appear, and in summer (June–July), the fruits mature, dispersing seeds. The leaves wither, leaving no trace of the plant above ground.
In autumn, the development cycle repeats. This unique biology is explained by the structure of the underground part of the plant. Underground, the plant develops a biennial fleshy corm of stem origin, covered with dark-brown membranous sheaths. The corm is oval-ovoid, up to 5 cm in length, weighing about 40 g, white and solid in cross-section without layers (resembling a potato). On one side of the corm, there is a notch where a new shortened flower stalk develops by autumn; the lower internode of the underground stem swells and grows into a new corm, while the old one, having exhausted its nutrient reserves, dies. The new corm produces 1–3 large, beautiful purple-pink flowers above the ground. The perianth is simple, with fused tepals forming a long cylindrical tube, expanding at the top into a funnel-bell-shaped six-lobed limb. The corolla tube is 20–25 cm long, but only 8–10 cm protrudes above the ground; the rest remains underground, with the base containing a superior trilocular ovary with three long styles extending above ground to the level of the stamens’ anthers. After pollination, the flower wilts, and the ovary overwinters underground, gradually developing into a fruit. In spring, the upper internode elongates and produces a stem barely emerging above ground, bearing four long, broad-oblong green leaves. Subsequently, a fruit capsule emerges above ground, initially green and turning brown as it ripens. The capsule is elliptical, trilocular, with the upper edges of the carpels free and extending outward. Seeds are numerous. The entire plant is poisonous.
Colchicum speciosum forms dense thickets in the subalpine forest zone, occurring in forest glades and edges on mountain slopes in the Caucasus at altitudes of 1800–3000 m.
Another species, Colchicum liparochiadys Woron., with larger corms (7–10 cm long, weighing up to 100 g), grows in Transcaucasia.
Corms of Colchicum are collected as Tuber Colchici. They are harvested in autumn during flowering. Fresh corms are stored on racks in a layer 10–15 cm thick in a cool place, with a shelf life of 3 months. The raw material is processed to extract alkaloids.
The corms contain alkaloids. The composition of the alkaloid mixture has been studied. Its basis is a tropolone ring. In addition to the well-known alkaloid colchicine, found in the Western European species Colchicum autumnale L., a new alkaloid, colchamin, has been isolated. Structurally, it differs from colchicine by having a methyl group instead of an acetyl group at the nitrogen atom. Both alkaloids have structures featuring one six-membered and two seven-membered rings. Other accompanying alkaloids are not of practical significance. Both alkaloids exhibit antitumor activity, but colchamin is significantly less toxic and therefore more suitable for medical use.
A 0.5% colchamin-containing ointment is used for skin cancer treatment, with a treatment course lasting 18–25 days. The ointment is toxic, requiring caution to avoid contact with mucous membranes. Treatment is conducted under medical supervision. For esophageal cancer, colchamin tablets are prescribed alongside sarcolysin and other substances. Previously, tinctures from the corms and seeds of the Western European Colchicum autumnale L. were used as local irritants for gout treatment. Colchicine and colchamin are also used in agricultural experiments to produce polyploid plant forms.
Colchicine has been found in other species of Colchicum and related genera of the Liliaceae family, such as Merendera and Gloriosa.
