THE BRYOPHYTA OF ICELAND 501 



198. Pogonatum dentatum (Menz.) Brid. 

 Var. minus (Wahlb.) Hagen. 



Reykjavik !. 



Here it grew in several places on peaty soil, and in one place very 

 abundantly, with numerous capsules, some of which were almost ripe 

 in the first half of August. 



199. Pogonatum urnigerum (L.) P. B. 



Polytrichum urnigerum L. 



Widely distributed over the whole of Iceland. 



Grows usually scattered as individual plants, or a few plants to- 

 gether, among other mosses on dry, humus-covered rocks or on the 

 ground, both dry and somewhat damp; for instance along the banks of 

 streams. It occurs in large quantities on peat, often forming large light- 

 green patches, interwoven with Alicularia scalaris and, occasionally, Sca- 

 pcinia ciirta. On somewhat damp, moss-grown slopes it often forms 

 large tufts several centimetres high among Hylocomium spp., Hypnum 

 uncinatum and Polytrichum alpinum; such vigorous forms are also fre- 

 quently met with in South Iceland on somewhat damp ground, for in- 

 stance by the sides of ditches. It is most frequent in the lowlands and 

 does not appear to ascend above 300 400 metres. The fruit, which 

 only occurs on large plants growing in tufts, was ripe or overripe in 

 the beginning of June. 



200. Polytrichum alpinum L. 



Ver3 r common everywhere both on dry and on somewhat damp 

 ground, and almost equally frequent from the sea-level up to the limit 

 of vegetation on mountain heights. It grows both mixed with species 

 of Hylocomium and interspersed in Rhacomitrium-mais on knolls in bogs, 

 on peat, in grass-fields and on the stony slopes of mountain heights. 

 The fruit, which occurs very frequently, ripens in the lowlands about 

 August 1st. 



Varies considerably in habit, length of leaf, form of capsule, etc., 

 but the majority of the forms, however, approach closest to the type. 

 Forms agreeing more or less with var. septemtrionale (Sw.) Brid. are 

 also common. 



201. Polytrichum formosum Hedw. 

 W. Iceland: "Steluhusid" in Sokkolfdalur (F.)!, sterile. 



202. Polytrichum gracile Dicks. 



Rather common over the whole of Iceland. 



This species grows in peaty soil, often abundantly, and sets fruit 

 almost always. It occurs only in the low land and has hardly been 



