335 



OBITUARY. 



Philippe Edouard Leon van Tieghem, Hon. F.R.M.S. 



1839-1914. 



By A. B. Rendle, M.A. D.Sc, F.R.S., etc. 



By the death of Professor Van Tieghem the Society loses one of 

 its most eminent Fellows, and the science of Botany one of its 

 most devoted and able adherents. Van Tieghem is best known 

 for his work on the comparative anatomy of the flowering plants, 

 many families or smaller groups of which he studied in detail. 

 In 1866 he published in the Annales des Sciences Naturelles an 

 important paper on the anatomical structure of the Aroideaj, and a 

 comparison of this family with Typhacete and Pandanacere, which 

 he regarded as two distinct groups connected by the Aroidere. 

 In this connexion he writes : — " Nos observations semblent de- 

 montrer ainsi par une preuve nouvelle qu'il est indispensable de 

 joindre l'etude anatomique comparee de l'appareil vegetatif a celle 

 de la fieur, si Ton veut construire le systeme ideal a liaisons fixes, 

 qui est l'objet de la methode naturelle." This was followed by 

 a long and valuable series of papers dealing not only with the 

 vegetative structure of the plant, but also with the comparative 

 structure of the pistil and other parts of the flower, the ovule, and 

 the seed. Perhaps the most fruitful was that entitled " Anatomie 

 comparee de la fieur femelle et du fruit des Cycadees, des Coniferes, 

 et des Gnetacees,"* in which he attacked the problem of the 

 morphology of the cone-scale from an anatomical point of view. 

 Arguing from the course and orientation of the vascular bundles, 

 he explained the seed-scale as the first leaf of an axillary branch, 

 and demonstrated the existence of a common anatomical plan in 

 the cone-scale throughout the Pinacete. In the application of the 

 results of his investigations to a system of classification, Van 

 Tieghem was less successful. He suggested the subdivision of 

 the Angiosperms into three groups, based on the development 

 of the growing-point of the root, as follows : — 1. Liorhizeas 

 Monocotylere, including Monocotyledons without the Grasses. 



2. Liorhizere Dicotyleae, comprising Grasses and Nymphpeacese. 



3. Climacorhizese or Dicotyledons, including Dicotyledons except 

 Nymphaeacere. For further subdivisions he relied primarily on 



* Ann. Sci. Nat., ser. 5, x. (18G9) pp. 269-304. 



