504 A. HESSE LBO 



to soil present certain points of resemblance to the mountain heights, 

 as the snow in the deep clefts, the bottom of which is never reached 

 by the rays of the sun, often remains till late into the summer. The 

 occurrence of var. tenellum is more peculiar. It has been found only 

 in S. Iceland, where it grew exclusively on dry or slightly damp blocks 

 of tuff in the lowlands. But only near Seljaland did a few small tufts 

 occur on a block of tuff at an altitude of about 600 metres. Near 

 Drangshlid it grew abundantly on the fallen blocks of rock at the foot 

 of the rock-wall behind the farm. There in company with Hijpnum 

 cup ressi forme, Ceratodon, Didymodon nibellus , Rhacomitrium fasciculare 

 and Brynm argenteiim it formed tufts of varying size on the top of the 

 blocks in dry situations. Near Barkarstadr it was found on a some- 

 what damp tuff- face, and creeping over fallen blocks of rock, in asso- 

 ciation with Pohlia crada, P. grandiflora, Ancectangium compaction., JBry- 

 oxiphium norvcgicum and Anthelia spp. The plants from these habitats 

 were quite sterile, and exactly alike in all respects. 



The fruit, which is common in the Alpine form, ripens in August 

 (Akureyri: ripe Aug. 13th; near Isafjordur: green in the first half of July). 



204. Polytrichum piliferum Schreb. 

 Polytrichiim pilosum Neck. 



Iceland (Morch)!. E.Iceland: Vallanes (H. J.;!). N. Iceland: Rey- 

 kjahlid (Grl. ;!). NW. Iceland; Bildudalur (C. Hansen;!); Gnupr near D\ra- 

 fjordur!; Armuli!; Arngerdareyri!. W. Iceland: Stykkisholmur (H. J. ;!); 

 Grund in Skorradalur!; common near Reykjavik! ; Vide} 7 !; Hafnarfjordur 

 (Wiinstedt) ! . S. Iceland: Krisuvik (Stp. ;)!; Drangshlid!. 



Occurs here and there, and is rather rare in the majority of the 

 districts of Iceland. It grows on dry sandy ground, upon soil-covered 

 rocks and on dikes, often singly among other mosses. It is absent from 

 or rare in the most rainy parts of the country, for instance at the East 

 coast and in South Iceland and is most frequent in those districts where 

 the rainfall is least. Thus it occurs abundantly near M \vatn, where it 

 is common in the lava-field. It is also rather widely distributed in 



> 



NW. Iceland, here it is often found in abundance, for instance on sandy 

 fields near Armuli and on rocks near Arngerdareyri. Fruit is common 

 and ripens in the latter half of June. 



205. Polytrichum juniperinum Willd. 



Commonly distributed. 



It grows on more or less dry ground, for instance on knolls in 

 bogs, in the Rhacomitrium-canescens heath, on slopes among Hylocommm 

 and Rhacomitrium etc., usually scattered among other mosses, more 

 rarely in cohering tufts, and almost always sets fruit which ripens at 

 the end of June and in the beginning of July (Seydisfjordur, July 6th; 

 Isafjordur, June 24th). 



It is most widely distributed in the lowlands and does not appear 

 to ascend much higher than about 400 metres above sea-level. 



