Chrozophora tinctoria

Chrozophora tinctoria (commonly known as dyer's croton, giradol, or turnsole) is a plant species native to the Mediterranean, the Middle East, India, Pakistan, and Central Asia. It is also present as a weed in North America and Australia. 
Description.
It is an annual, typically found in nutrient-poor ground. It develops a large taproot. The plant is erect and covered with wool-like hairs. The ash-green leaves are alternate. The tiny monecious flowers are grouped in a raceme. The lower, female flowers lack petals and the upper male flowers have five small yellow petals. Pollination is by ants. The fruits are conspicuous and consist of three dark green conjoined spheres. Their surface is decorated with white scales and warty structures. Each sphere contains three seeds, which are propelled away from the plant by the mechanical force of the mature fruit twisting as it opens.
Use for dye.
"Chrozophora tinctoria" produced the blue-purple colorant "turnsole" (also known as katasol or folium ) used in medieval illuminated manuscripts and as a food colorant in Dutch cheese and certain liquors. The colour comes from the plant's fruit, specifically its dry outer coat.
In 2020, an interdisciplinary team of researchers from FCT NOVA, University of Porto and University of Aveiro, identified the complex chemical structure of the medieval purple-blue dye extracted from the fruits of "Chrozophora tinctoria". The chemical structure of the medieval dye was a mystery until now. The extracts obtained showed a novel blue chemical, chrozophoridine as the main chromophore.