Urucum

Martius found most dressed in bits of clothing, their hair wildly tangled and their faces dyed red with urucum.

They paint them, or at least parts of them, with urucum (reddish) plant dye or even their own blood if there are no urucum plants nearby.

Bixin results from lycopene oxidation and it is the main carotenoid found in the seed coat of urucum fruits (Bixa orellana L.), which is cultivated in tropical countries of South and Central America, Africa and Asia.