Researchers at Florida International University in Miami have discovered the 'animal' pigment bilirubin in the seeds of the white bird of paradise tree, Strelitzia nicolai. This is the first example of bilirubin occurring naturally in plants.
Cary Pirone and her colleagues cannot yet account for the presence of the bright orange substance, which is a product of the breakdown of the haem chemical group that, in animals, is found in haemoglobin. In plants, haem's normal metabolic product is the light-sensing pigment of the important protein phytochrome.
Although the plant the team studied has white flowers (pictured), the seed part, called the aril, has the hue of oxygenated blood.