  Next, Albert studies the plant kingdom. In his Treatise on Plants (De vegetabilibus), as in his Treatise on Minerals, he combines his own observations with those of other authorities, providing an alphabetical list of plants as he did for stones in his Treatise on Minerals. But he adds a long section on the cultivation of plants. He makes the interesting observation that the properties of certain plants are caused by celestial bodies. He also indicates the medicinal properties of certain plants, although he is careful to point out that his principal concern is in understanding the nature of plants based on a study of their properties and virtues.