Phytochrome photosynthesis, artwork. The molecule of the protein phytochrome (top) forms a complex with a light-sensing pigment (inset at lower centre). This protein and the pigment are used by plants to govern basic processes such as seed germination (shown here). At left, the seeds in the pot have been planted too deep in the soil and the seeds will not germinate because the light cannot reach them. At right, the seeds are close enough to the surface for light to reach them, and they have germinated.