Studies on Anthocyanidin and Leucoanthocyanidin in Autumnal Red Leaves and Green Leaves of the Cenifers

Anthocyanidins in the coloured leaves and leuco-anthocyanidins in the green leaves of the conifers were investigated by means of paper chromatography and spectrophotometry.The results can be summarized as follows:1. The red colours of the conifers' autumnal leaves seem to be mostly due to anthocyanins.2. The anthocyanidin present in the coloured leaves is identified with cyanidin or delphinidin; some species contain both cyanidin and delphinidin, some, cyanidin, ut none contains delphinidin. These anthocyanidins may not be produced solely from the anthocyanins but from the leuco-anthocyanins co-occurring in the autumnal leaves.3. The leuco-anthocyanin present in conifers' green leaves is converted into cyanidin or delphinidin by heating with 2N-HCl.4. Anthocyanidins formed from leuco-anthocyanins in the green leaves are generally the same as found in the coloured leaves of the same species.5. The kind of anthocyanidin and leuco-anthocyanidin found in the coloured and the green leaves is characteristic of systematic position of the plants; there are more species which contain leuco-delphinidin than those which produce both delphinidin and cyanidin among Pinaceae, while species which form both delphinidin and cyanidin are more common than those giving cyanidin alone among Taxodiaceae and Cupressaceae.6. Leaves of major species of Pinaceae give delphinidin alone when heated with HCl and do not change their colour in autumn or in winter.7. The systematic distribution of anthocyanidin and leuco-anthocyanidin in the coloured and the green leaves suggested that Metasequoia is closely related to Sequoia and Sequoiadendron among Taxodiaceae.