80 BERNT LYNGE. M.-N. Kl. 



(LYNGE). Finmarken: Konsamfjeld (WAHLENBERG) and Talvik (BAUR) in 

 Alten; Honningsvaag, Osterbotn, Lakselv, and Skoganvarre (LYNGE) in 

 Porsanger; Vadse (HAVAAS); Naesseby (Tn. FRIES), and Sjaaholmen (TH. 

 FRIES) in Varanger. 



It is only to be expected that a plant of this frequency and wide 

 distribution should be a variable species. A part of the variation is directly 

 due to the substratum, e. g. the elongate, stellate laciniae of plants, grow- 

 ing on fla't slates, and the more irregular, shorter, broader, and more 

 imbricate, at the circumference more or less free laciniae of plants, growing 

 on rugged granite, or on mosses (f. muscicola SCHAER.). 



In some plants the isidia are absent, in others developed at the mar- 

 gin of the laciniae (f. sciastra), or about the centre also on their 

 surface, more rarely over the whole thallus, entirely covering the laciniae. 

 It is evident that isidiate plants commenced their existence without isidia, 

 and undoubtedly many of the nuda or sciastra plants develope into 

 more isidiate stages; in that case they only represent different stages of 

 age. On the other hand I have seen numerous full-grown plants showing 

 little tendency to form isidia. It is, accordingly, very questionable whether 

 we should regard them as stages of individual development, or as types 

 of variation. Anyhow it is quite impossible to divide Ph. lithotea into well 

 limited varieties after the isidia, for there are all intermediate states be- 

 tween a naked thallus and a thallus, entirely covered with isidia. 



Occasionally the thallus has a tinge of bluish-violet, which calls to 

 mind pruinose forms of Ph. muscigena. I have, however, never seen 

 pruina in Ph. lithotea. The colour is to some degree dependent on the 

 insolation: dark in strong insolation, pale in plants growing in the shade. 

 This is distinctly seen on plants growing over sharp edges into shadowed 

 positions. 



The upper cortex is thinner than in Ph. obscura, and the hyphae 

 more thin-walled; in both species they are constrictedly septate, almost 

 moniliform. 



In some foreign floras * apothecia are reported to be rare, in Norway 

 fertile plants are very frequent. The greatest, especially the broadest 

 spores have been measured in muscicolous plants, but a statistical group- 

 ing of the dimensions only gives a one-topped curve, indicating one 

 type. The anatomical investigation of thallus and apothecia gives no 

 basis for the division up of Ph. lithotea. In every section there are 



CROMBIE Brit. Lichens I p. 319. 



