*[http://www.plantillustrations.org/about.php Plant illustrations]
*[http://calphotos.berkeley.edu/ CalPhotos]. (University of California, Berkeley). 265 000 photos de plantes, sous des licences différentes.
*[http://www.bodleian.ox.ac.uk/science/resources/sherardian-library/flora_graeca Sibthorp, John, ''Flora Graeca and '' et ''Florae Graecae Prodromus''] à la Radcliffe Science Library