phycochrome
/ˈfʌɪkəkrəʊm/noun
In early use: a blue-green pigment (believed to be a combination of chlorophyll and phycocyan) present in blue-green and certain other algae. Later: any photoconvertible pigment (phycocyanin, phycoerythrin, etc.) present in algae and cyanobacteria (blue-green algae).
Origin
Mid 19th century; earliest use found in Quarterly Journal of Microscopical Science. From phyco- + -chrome, after German Phycochrom. With sense 1 compare French phycochrome.