Herbage Studies. II.–Variation in Lotus corniculatus and trifolium repens (Cyanophoric plants)

Abstract

In Part I of these studies, it is shown that Lotus corniculatus is a plant in which a glucoside containing cyanogen is frequently present together with the corresponding enzyme. During 1911 we were able to make observa­tions practically over the whole of Europe, owing to the assistance we received from Dr. Eyre, which led us to the conclusion that the glucoside and enzyme were normal constituents of the plant in almost all districts, though occasionally, in close proximity to plants which were cyanophoric, others were met with in which little if any cyanide could be detected. In Scotland, in South Ayrshire, the plant was uniformly acyanophoric , except on the coast; nor could cyanide be detected in plants collected in Norway. Lotus major, which is a sufficiently distinct variety to have been recognised by botanists as a separate species, was uniformly free from cyanide and also apparently from enzyme; but no regular distinction could be made between the various other forms which botanists look upon as merely varieties of the plant. Lotus major, it should be added, always affects damp situations and is a rank grower; it can be distinguished by the manner in which the large number of flowers in the umbel spread out from a common centre instead of at intervals from the flower stalk; the calyx teeth also tend to spread outwards, whereas in other forms they are almost uniformly strongly incurved. We have found the double form of L. corniculatus (var. pleno ) to be strongly cyanophoric.