https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/14021886Edit ImageSaveSaveEditCropCustom TextBlack knapweed plant (Centaurea nigra): flowering stem. Coloured lithograph by F. Waller, c. 1863, after C. Gower.Original public domain image from Wellcome CollectionMorePublic DomainFree CC0 image for Personal and Business useInfoView CC0 LicenseJPEGSmall JPEG 754 x 1200 px | 300 dpiLarge JPEG 1300 x 2068 px | 300 dpiFree DownloadBlack knapweed plant (Centaurea nigra): flowering stem. Coloured lithograph by F. Waller, c. 1863, after C. Gower.More