A pigment that controls most photomorphogenic responses in higher plants. As a result of the dependence of plants on the energy of sunlight and their sessile habit, mechanisms have evolved that allow them to adapt their growth and development to more efficiently seek and capture light and to tailor their life cycle to the climatic seasons. These mechanisms enable the plant to sense not only the presence of light but also its intensity, direction, duration, and spectral quality, which suggests a form of colour vision. Plants thus regulate important developmental processes such as seed germination, growth direction, growth rate, chloroplast development, pigmentation, flowering, and senescence, collectively termed photomorphogenesis.