Carline Thistle (Carlina), a beautiful genus of Compositeæ, closely allied to the true thistles, from which they are distinguished by the inner spreading bracts of the involucre, which, coloured and shining, are remarkably hygrometric, expanding in dry and closing together in wet weather, and this property they retain for a long time; the heads of flowers are therefore often nailed on cottage-doors in many parts of Europe to indicate the weather. The name is said to be derived from a legend that an angel showed the root of one of the species, C. acaulis, to Charlemagne as a remedy for a plague in his army. Linnæus, however, tells the story, without the angel, of the army of Charles V., while the most sceptical regard the name as merely a corrupt diminutive of Ital. cardo (dim. cardina), 'a thistle.' The root is certainly a drastic purgative, and hence was formerly held in high medical repute; now, however, it is quite disused, save in veterinary practice. The only British species is C. vulgaris.