phytochrome

[ fahy-tuh-krohm ]

noun

, Botany.

1. a plant pigment that is associated with the absorption of light in the photoperiodic response and that may regulate various types of growth and development.

phytochrome

/ ˈfaɪtəʊˌkrəʊm /

noun

1. botany a blue-green pigment existing in two interchangeable forms, present in most plants, that mediates many light-dependent processes, including photoperiodism and the greening of leaves

phytochrome

/ fī′tə-krōm′ /

1. Any of a group of cytoplasmic pigments found in green plants and some green algae that absorb red light and regulate dormancy, seed germination, and flowering. Phytochromes consist of a bile pigment attached to a protein, and occur in an active and inactive form, each of which can be converted into the other depending on the wavelength of red light that is absorbed.

Word History and Origins

Origin of phytochrome¹

First recorded in 1890–95; phyto- + -chrome