De l’Obel’s arrangement, in spite of its good features, had serious drawbacks. The anomalous Monocotyledons, such as _Arum_, _Tamus_, _Aloe_ and _Ruscus_, are scattered among the Dicotyledons, while _Drosera_ (the Sundew) appears among the Ferns, and so on. Similarities of leaf form, which are now regarded merely as instances of “homoplastic convergence,” are responsible for many curious groupings. For instance in the ‘Kruydtbœck’ we find the Twayblade (_Listera_) the May Lily (_Maianthemum_) and the Plantain (_Plantago_) described in succession, while, in another part of the book, various Clovers (_Trifolium_), Wood Sorrel (_Oxalis_) and _Anemone hepatica_ are grouped together. It is also not surprising that the Marsh Marigold (_Caltha_), the Waterlilies (_Nymphæa_ and _Nuphar_), _Limnanthemum_ and Frogbit (_Hydrocharis_) should follow one another, or that de l’Obel should have brought together the Broomrape (_Orobanche_), the Toothwort (_Lathræa_), the Bird’s-nest Orchid (_Neottia_) and a number of Fungi. In these latter instances the author has really arrived at genuine biological (though not morphological) groups. He has recognised, on the one hand, the marked uniformity of the type of leaf characteristic of “swimming” water-plants, and, on the other hand, he has observed the leaflessness and absence of green colour, which are negative features common to so many saprophytes and parasites. [Illustration: Text-fig. 69. “Tussilago” = _Tussilago farfara_ L., Coltsfoot [Fuchs, De historia stirpium, 1542]. _Reduced._]