https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/14009693Edit ImageSaveSaveEditCropCustom TextTwo plants, a knapweed (Centaurea jacea) and star-thistle (Centaurea calcitrapa): flowering and fruiting stems. Coloured etching by C. Pierre, c. 1865, after P. Naudin.Original public domain image from Wellcome CollectionMorePublic DomainFree CC0 image for Personal and Business useInfoView CC0 LicenseJPEGSmall JPEG 832 x 1200 px | 300 dpiLarge JPEG 1546 x 2229 px | 300 dpiFree DownloadTwo plants, a knapweed (Centaurea jacea) and star-thistle (Centaurea calcitrapa): flowering and fruiting stems. Coloured etching by C. Pierre, c. 1865, after P. Naudin.More