The colouring matter of the blue pansy

Abstract

In two previous papers dealing with the colouring matters of red flowers, the author has shown that the anthocyanin pigments contained in the petals of the red rose (“ George Dickson ”)* and the scarlet pelargonium (“ James Kelway ”) are di-glucosides of cyanidin and pelargonidin respectively, and the reason for these flowers being red in colour is due to the fact that these glucosides occur in the petals, in combination with plant acids, in the form of oxonium salts. Following on these results, it was decided next to examine the petals of blue flowers and endeavour to obtain an insight into ( a ) the nature of the blue pigment, ( b ) the state in which the blue pigment is present in the petals, and ( c ) the nature of any yellow sap pigments which might also be present in the same flowers. For this investigation a variety of bedding pansy (“ Emperor William ”) was chosen, the petals of which possess a magnificent azure blue colour, with a darker centre. The blue pigment (anthocyanin pigment) was isolated in the form of its chloride, for which purpose the whole petals—including the darker central portions—were used, as preliminary experiments showed that extracts of the darker portions at the centre of the petals had the same properties as those of the bright blue outer parts. The plants from which the flowers were gathered were grown by the author, from seedlings purchased from Messrs. Arthur Yates & Co., Sydney.