Coltsfoot

A low creeping perennial of clay banks, verges and disturbed ground across Europe and Asia, spreading by rhizome. It flowers very early — dandelion-like yellow heads on scaly leafless stalks in late winter — and only afterwards puts up the broad hoof-shaped leaves that give it both its common and Latin names. Leaf and flower are gathered separately and dried.

Coltsfoot carries mucilage and, more importantly, a class of alkaloid that determines how it can be used at all.

Coltsfoot is a pyrrolizidine alkaloid plant, in the same category as borage leaf and comfrey, and this is the fact that governs everything about it. PAs are metabolised in the liver into reactive compounds that accumulate, and the damage is cumulative rather than acute — which is why several European countries restrict coltsfoot, why low-PA cultivars were developed specifically for the herbal trade, and why any traditional account of long-term use should be read against a modern safety file that did not exist when those accounts were written.

Recorded in European practice from Dioscorides onward and long used as a domestic preparation, with the dried leaf also smoked. It was the sign hung outside French apothecaries.

The damage is cumulative rather than acute.