Three British wild flowers, including hedge mustard (Sisymbrium officinale) and woad (Isatis tinctoria). Coloured… https://www.rawpixel.com/image/13968491/image-flower-plant-medicineFree Image from public domain licenseWoad (Isatis tinctoria L.): flowering stem with separate sections of fruit and flower. Coloured etching by M. Bouchard, 177-. https://www.rawpixel.com/image/13957170/image-flower-plant-grassFree Image from public domain license