An examination of the flowers of nineteen species of the genus Lathyrus, which presented a considerable range in colour from red to blue, has revealed a marked uniformity in the anthocyanin pigments. Up to three closely related anthocyanidins were found in each species, namely, delphinidin, petunidin and malvidin. No other anthocyanidin was detected in any species. The pigments occurred as monoglycosides, not as diglycosides as reported by earlier workers, and behaved chromatographically as 3-monoglucosides. L. sativus L. was exceptional, however, in that all the pigment was apparently present as free aglycone.

Blueness of whole flowers or of wing petals was frequently correlated with, and is believed to be due to, the presence of the flavonols quercetin and kaempferol.