The genus contains only one species, Sherardia arvensis, the (blue) field madder, which is widespread across most of Europe and northern Africa as well as southwest and central Asia (from Turkey to Saudi Arabia to Kazakhstan) and Macaronesia (Canary Islands, Azores, Madeira, Savage Islands).

[1] It is also reportedly naturalized in Australia, New Zealand, Taiwan, Kerguelen, Ethiopia, Sudan, southern Africa, Mexico, Costa Rica, South America, Bermuda, Cuba, Haiti and much of Canada and the United States (especially the Pacific States and the lower Mississippi Valley).

[2][3][4] Sherardia arvensis is an annual plant with trailing and upright stems growing up to 40 cm long, having a square cross-section.

The rough pointed bristly leaves of about 1 cm in length are in whorls of four to six (normally six at the ends of the shoots, but four nearer the root).

The tiny pale lilac or pink flowers are approximately 3 mm in diameter and have a long tube, with only the end part of the four petals free.