BERNT LYNGE. M.-N. Kl. 



Nylander ^ raised the »tribus« Physcia (sensu Friesii) to the rank of 

 a genus, also comprising our Xanthoria on account of the spores which 

 are one-septate in these genera. In this last particular Nylander was 

 followed by later English and French authors (Crombie, Harmand, and 

 Hue). On account of the uncoloured spores Th. Fries ^ separated Xan- 

 thoria from Pliyscia. His genus Pliyscia comprised our Physcia as well 

 as Aitaptychia, but later on he separated them as subgenera-^, being well 

 aware of the importance of the anatomy of the thallus. 



All the above authors were of the opinion that the Physciaceae and 

 the Parmeliaceae were nearly related families. In the meantime the theory 

 of the evolution of species began to free several of the former great sec- 

 tions of systematic botany, which were henceforth to be regarded as poly- 

 phyletic sections. — From different origins the plants had assumed con- 

 vergent forms, either due to cognate reaction on the same exterior cir- 

 cumstances, or to cognate and innate tendencies of variation. 



Thus the large section Lichenes Phylloblasti Kbr. was regarded as 

 the most highly developed representative of different series of evolution. 

 In some cases the pedigree is relatively clear, in many cases not There 

 are very few fossile Lichens, for the highly transient thallus of the 

 Lichens does not contain parts capable of preservation during geological 

 periods. 



The fundamental work by Walxio: Etude sur la classification 

 .... des Lichens du Brézi! (1890) is based on the modern view, 

 which is theoretically considered by Reinke in his Abhandlungen über 

 Flechten IV — V (1895 — 1896), and constructed in detail by Zahl- 

 bruckner in Die Natürlichen Pflanzen familien (1907). 



Wainio draws up a section Buellieae. comprising the genera Anap- 

 tychia, Physcia, Pyxine, Rinodina, and Buellia. Physcia is removed from 

 relationship with the other foliaceous Lichens, and — on account of the 

 dark, septate spores — placed with the above mentioned genera, gathered 

 from very different parts of the old system. Reinke follows Wainio, only 

 using the name Physciaceae instead of Buellieae. Zahlbruckner divides 

 the section into two families: Buclliaccae, comprising the two crustaceous 

 genera Buellia and Riiiodiua, and Physciaceae, with the three foliaceous 

 genera Pyxine, Physcia, and Anaptychia. 



1 Nylander: Classif. 2, p. 174. 



2 Fries, Th.: Lichenes Arctoi (i860) p. 66. 



3 Fries, Th.: Lieh. Scand. L (1871) p. 132 et 135. 



