The site and chemical nature of red pigmentation in seedlings

Hypocotyls of 76 species of dicotyledonous seedlings, drawn from 30 families, were surveyed for tissue site of red pigmentation. In 42 species, red pigments were borne by a single layer of cells. Two layers were pigmented in 19 species and several layers in 15. Hypocotyl extracts of 61 species were analyzed for anthocyanidins. Pelargonidin was the major pigment in only one. Cyanidin alone or in combination with pelargonidin or delphinidin was identified in 37 species and probably present in 11 more. Delphinidin and its derivatives malvidin and petunidin were found in members of the Solanaceae. Delphinidin and malvidin were also major pigments in two Phaseolus species. Anthocyanidins were not detected in the four members of the Centrospermae examined.