Plant 197

Colchicum autumnale L. (Colchicaceae)


Autumn crocus

Colchicum autumnale can be a surprising sight in autumn, its pale mauve flowers suggesting that spring has arrived six months early. The six-petalled, goblet-shaped flowers have a superficial similarity to true crocuses, inspiring its common name; the true crocus is a member of the family Iridaceae. The autumn crocus is native to Britain, continental Europe and North Africa and commonly cultivated in gardens. The flowers appear long before the leaves, which follow in spring; a trait that has led to another common name, naked ladies.

A third common name, meadow saffron, is dangerously misleading. It would be unwise to use Colchicum as a spice, as it contains the toxic alkaloid colchicine; true saffron is a crocus, Crocus sativus. Numerous deaths have been attributed to Colchicum poisoning. Often the plant is mistaken for wild garlic (Allium ursinum), the two species producing somewhat similar leaves. The symptoms of colchicine poisoning are particularly unpleasant; described as similar to cholera, they include pain in the throat and stomach, vomiting, and failure of the kidneys and respiratory system. Death can take several days, whilst survivors may experience symptoms for years afterwards.

The autumn crocus has found application in medicine, most frequently as an external treatment for gout, where its success is probably due to its anti-inflammatory action. Use of Colchicum for rheumatism was reported in the fifth century CE, and in the seventeenth century John Gerard recommended that the roots be 'stamped, mixed with eggs, barley meal and crumbs of bread, and applied plasterwise' to afflicted areas. Meadow saffron's widespread adoption in Europe was probably due to the successes reported by Edward Howe in nineteenth-century London.

Meadow saffron's use in modern medicine is limited. It was briefly used to treat leukaemia, before being withdrawn due to side effects. It has a low therapeutic index (the window where the strength of the dose is effective without being dangerous) meaning it is easy to overdose accidentally. In the USA, in 2007, an incorrectly prepared batch of colchicine-based medicine claimed three lives resulting in tighter controls on its use. Colchicum is a good example of how the difference between medicine and poison is a matter of degree.

Colchicine, which interferes with cell division, is used in plant breeding to increase the number of chromosomes inside individual cells. Such polyploidy plants often have important economic traits, such as being bigger and hardier than their close relatives with fewer chromosomes.

Further reading

Jung LS et al. 2011 Biological Flora of Central Europe. Colchicum autumnale L. Perspectives in Plant Ecology, Evolution and Systematics 13: 227-244.

Ruth Calder