I9l6. No. 8. MONOGRAPH OF THE NORWEGIAN PHYSCIACEAE. 37 



Physcia leptalea var. tenella (p. p.) HARMAND Lich. France (1909) p. 621. 



Physcia ascendens BITTER Ueber die Variabilitat einiger Laubflechten 

 etc. (1901) p. 431 et 433 fig. 3 AB BOULY de LESDAINS Recherches sur 

 les Lichens des Environs de Dunkerque (1910) p. 107 (sensu latiore). 



The synonymy of Physcia ascendens and Ph. tenella is very intricate 

 and has been still more complicated on account of the divergent opinion 

 of the lichenologists as to their specific difference. It is therefore im- 

 possible to give a full list of synonyms without a study of the various 

 authors' material. They were first separated as two species by BITTER 

 (1. c.), but many eminent lichenologists (e. g. HARMAND) consider them to 

 be merely individual variations produced by different degrees of humidity 

 and temperature. 



1 have carefully studied the question in nature and on a large her- 

 barium material, with the result that I agree with BITTER. The two spe- 

 cies frequently grow together on the same tree, they are even entangled, 

 the laciniae of one of them making their way between the laciniae of the 

 other species. But a cautious examination will always enable us to sepa- 

 rate them, and I have never seen their characters combined in one spe- 

 cimen. In addition to the morphological characters we may mention that 

 Ph. tenella is frequently fertile, Ph. ascendens usually sterile. They have 

 not the same distribution : Ph. tenella is recorded as far north as Tromse, 

 Ph. ascendens only to Trondhjem, Ph. ascendens is a lowland plant, Ph. 

 tenella a coast lowland plant. In Norway Ph. tenella is much more fre- 

 quent than Ph. ascendens. 



Exsicc. ANZI Lich. Ital. super. 119 (Parmelia stellaris L var. tenella 

 (Scop.)), FRIES Lich. Suec. 206 B (P. stellaris), HEPP Flecht. Eur. 879 

 (Lobaria tenella (Scop.) HEPP.), LEIGHTON Lich. Brit. 174 (Borrera te- 

 nella ACH.), MALBRANCHE Lich. NORM. 71 (Ph. stellaris var. leptalea NYL.). 

 MALME Lich. Suec. 157 (Physcia tenella), MERRILL Lich. Exsic. 112 (Physcia 

 tenella (Scop.) NYL.), SCHAER. Lich. Helv. 352 (Parmelia stellaris 8 tenella 

 SCHAER.) et 607 dext. (coll. nob. s. n. Farm, obscura | virella SCHAER.), TUCK. 

 Lich. Amer. sept. 84 (Parmelia stellaris (i hispida FR.). ZAHLBR. Krypt. 

 Exsic. Vindob. 248 (s. n. Physcia tenella). (Scop.) NYL., 880. 



Thallus growing in small or middle-sized rosettes, diam. 2 3, rarely 

 5 8 cm. Laciniae at their ends free from the substratum and more 

 or less ascending; they are rather compact, imbricate, short, 0,5 i mm. 

 broad, widened at the apices, convex or semi-cylindrical, bi-or tri-furcate, 



