One of the best works on natural history produced during the Middle Ages, and, like most of Albertus's works, influential throughout the medieval period, though it does not appear to have been published in print until 1867. It was written about 1250, and is based on Albertus's own accurate botanical observations, also containing some therapeutic material. See Karen Reeds, "Alberto e la philosophia naturale della vita della plante," IN: Weisheipl (ed.) Albertus Magnus and the Sciences (1994) 367-380. Digital facsimile from the Biodiversity Heritage Library at this link.