EARLY FLOWERING 3 (ELF3) is a plant-specific gene that encodes the hydroxyproline-rich glycoprotein and is required for the function of the circadian clock. ELF3 is one of the three components that make up the Evening Complex (EC) within the plant circadian clock, in which all three components reach peak gene expression and protein levels at dusk. ELF3 serves as a scaffold to bind EARLY FLOWERING 4 (ELF4) and LUX ARRHYTHMO (LUX), two other components of the EC, and functions to control photoperiod sensitivity in plants. ELF3 also plays an important role in temperature and light input within plants for circadian clock entrainment. Additionally, it plays roles in light and temperature signaling that are independent from its role in the EC.