148 OLAF GALL0E 



into it(Ment/, 1900; Sernander, 1901 ; Galloe, 1908 and 1913). The 

 podetium-branch thus anchored forms new vertical branches, which 

 in turn also die away below, etc. All the vertical podetium -branches 

 and podetia, which are naturally very slightly attached to the ground 

 (by the decaying bases), are mutually connected by numerous hap- 

 tera, which hold them so closely together, that it is impossible to 

 obtain uninjured any isolated podetium from a tuft. 



The characteristic features of this type are, that the primary 

 thallus (here crustaceous) very soon dies, and that the podetia (at 

 the edge of the tuft) may lie down horizontally and wander in this 

 way, attached to the ground and to one another by haptera, while 

 they die away at the base, and keep on living perhaps for centuries 

 at their apex. 



The podetium-wanderer is an excellent earth-lichen-type, cap- 

 able of competition beyond any of the others, by the fact of its 

 dying away at the base, and keeping on growing at the apex, which 

 enables it to grow above both crustaceous and foliaceous lichens, 

 and also above hypothallus- and primary-scale-wanderers. The type 

 is consequently exceedingly rich in individuals in nature; reindeer 

 moss, as is well-known, is the most abundant earth-lichen in the 

 world. But the type is poor in species. It is not adapted to life on 

 rocks and trees, for its dying away at the base would deprive it of 

 its substratum. 



The primary-scale wanderers are represented by Cladonia 

 foliacea, which is in reality intermediate between a fruticose and a 

 foliaceous lichen. The spore, on germinating, quickly forms a pri- 

 mary thallus consisting of large, well developed lobes, which spread 

 out in a tuft-formation over the ground, while the hypothallus de- 

 cays quickly. Along the edge of the tuft the lobes lie horizontally, 

 but towards the centre they stand upright. They die away at the 

 base, and keep on growing at the apex, exactly as in Cetraria, for 

 instance. They are closely connected with one another by numerous 

 haptera, which prevent them from being scattered to the winds. 

 Consequently, so far, C. foliacea is a foliaceous lichen, but podetia 

 may also be developed on the lobes of the thallus although not 

 frequently in Denmark or in Iceland - - which makes it impossible 

 to include it, as a matter of course, among the foliaceous lichens. 

 The primary-scale wanderers, as regards their competitive capacity, 

 are like the lower species of the erect foliaceous lichens; they are 

 few in number both as regards individuals and species. The fact 



