Eranthis hyemalis Salisb. Ranunculaceae Winter Aconite Distribution: Europe. The reason it was called Winter aconite and linked to Aconitum napellus as being just as poisonous is because plants were classified according to leaf shape in the 16th century. L'Obel's Stirpium adversaria nova (1571) and Plantarum seu stirpium historia (1576) (with a full page illustration on page 384 showing Eranthis and Aconitum together) along with the knowledge that related plants have similar medical properties caused the belief that Eranthis are as poisonous as Aconitum. They are both in Ranunculaceae and while Eranthis (like all Ranunculaceae)is toxic if eaten, it does not contain the same chemicals as Aconitum. Caesalpino (Ekphrasis, 1616) pointed out the error in classifying according to leaf shape and recommended flower shape. It contains pharmacologically interesting chemicals such as khellin, also present in Ammi visnaga. This is a vasodilator but quite toxic, but can be converted into khellin analogues such as sodium cromoglicate – used as a prophylaxis against asthma attacks – and amiodarone which has anti-arrhythmia actions so is used for atrial fibrillation and other arrhythmias. It is endangered and protected in the wild (Croatia) because of over-collecting for horticulture. Photographed in the Medicinal Garden of the Royal College of Physicians, London.