66 Lichenes. 



which he has found in the dunes on Salix, Hippophae, dead grass 

 etc.; and he especially calls the attention to the great part, which 

 the rhizins, covering the lover surface of the leaves, play by absorbing 

 the drops of water like blotting paper. 



An extended account of the species of the heaths then foUows; 

 the author, classifies them as those, found in the inland sands, in the 

 Calluneta and in the Ericeta. The inland sands are a sort of small 

 deserts where the Vegetation is very scarce, the ten lichens found 

 here chiefly belong to the genus Cladonia and they are almost the 

 same species as were found in the dunes; besides 3 small and 

 insignilicant species are found on the pebbles. In the regulär Callu- 

 netum the lichens cannot live as long as the Calhma is in füll growth , 

 and has its füll height and thickness, but if the soil is so bad, that 

 the Calluna cannot cover it, or if man has peeled off the same, a 

 rieh Vegetation of bushy lichens will appear, especially Cladonia 

 rangiferina, and in places, where the soil is still worse, only some 

 crusty lichens are found. The author enumerates 37 species growing 

 on the ground and 17 species, growing on the Jiiniperus, Calluna 

 etc. Zukal and Mentz say that Cetraria islandica has a very slight 

 power of absorbing water, and in so far it is correct, as it only 

 absorbes very little water from the ground through its interior 

 tissue, but it exceeds all other lichens in absorbation of rain and 

 dew, as the flaps of its leaves are sloping and folded lengthwise 

 like a gutter, and its ends are flattened so as to be easily able to 

 catch the raindrops, which are absorbed by the thin cortex of the 

 Upper surface of the leaves, while they -flow down the gutter. 



When growing in better soil the bushy lichens will always 

 prevail upon the Lecidia tdiginosa Schrad., so its presence always 

 proves the soil to be acid and moorlike; the same is the case with 

 Lecidia decolorans Hoffm. 



In the more dr}" Ericeta the Cladonia rangiferina thril^es still 

 better than in the Callunetum, but in the moister Ericeta all lichens 

 disappear. As growing in the Ericeta the author enumerates 10 species 

 and as growing in the moister moors of the Callunetum 7 species» 

 which, however, are all very scarce. 



The moors themselves have no lichens as long as they are 

 thoroughly soaked, but as soon as they are so dr}", that Callnna is 

 able to grow there, the lichens will invade at the same time; still 

 the lichens have difficulty in existing in such places, except where 

 the heather is cut by man, for then a rieh Vegetation of lichens will 

 appear, but only to disappear as soon, as the heather grows up again. 



The lichens of woods are treated according to the different sorts 

 of trees, forming the woods. The author classifies the trees according 

 to the mass of light, which they suffer to pass through their crowns. 

 All sorts of trees will be differentty influenced if the trees are iso- 

 lated or growing in stock. 



The shadow of Abies pectinata, Picea excelsa and alba is so deep,. 

 that no lichens are found on their trunks or on the ground beneath; 

 but if they loose their needles f. inst, by being attacked by Lopho- 

 derniium, some of the same lichens as found in the heaths , will appear 

 on the ground togetber with Aira and Calluna. If a Single Picea is left 

 in the middle of the wood, while all trees round it are cut, its trunk 

 will quickly be covered with Lecanora varia f. straminea, which 

 is later on overgrown by leafy lichens. Picea alba, planted as 

 protection from the wind, quickly grew bearded by Usnea and 

 Cornicidaria jubata L. The author enumerates 6 species on Abies and 



