Illustration of a leghaemoglobin molecule. Leghaemoglobin is a protein capable of binding molecular oxygen. It is similar to mitochondrial haemoglobin with a single haem group, shown in rod model, centre. Oxygen molecules (red spheres) are shown binding to the iron centre of the haem site. Leghaemoglobin is found in the nitrogen-fixing root nodules of leguminous plants. It is produced by legumes in response to the roots being colonised by nitrogen-fixing bacteria. Leghaemoglobin has been used in plant-based burgers to give a meat-like 'bloody' burger.