540 A. HESSELBO 



are only forms of H. giganteum, which often occurs in slender, slightly 

 branched forms, which are very difficult to distinguish from H. cordi- 

 foliiim. As a rule, however, the old typical shoots from the previous 

 year may be found at the bottom of the tuft, from whence the cordi- 

 folium-like shoots proceed. Near Grunnavik H. cordifolium grew abun- 

 dantly on boggy, partly inundated ground, and there it was richly 

 fruiting. On the damp ground it was flaccid and prostrate, in water 

 erect in large, deep cushions. 



312. Hypnum Richardsonii (Mitt.) Lesq. et James. 

 Amblystegiiim Richardsonii Lindb. 



E. Iceland : Skorastadr (H. J.)! fr.; Seydisfjordur!, abundantly at an 

 altitude of 350 metres. N. Iceland: Thorodstadaengjar (St.)!; Ljosavatn! 

 fr., at an altitude of about 250 metres; Husavik!. NW. Iceland: Ar- 

 muli!. \V. Iceland: Modruvellir!, at an altitude of about 200 metres; 

 Hjallahals (H.J. ) !. S. Iceland: Barkastadr!, at an altitude of 530 metres. 



This species is probably more frequent than may be believed, 

 judging from the few habitats, but it is often overlooked on account of 

 its resemblance to the exceedingly common H. cuspidatum and H. gigan- 

 teum. It grows in bogs, often abundantly, associated with H. sirami- 

 neum, H. sarmentosnm, H. revolvens, H. exannulatum, etc., and often sets 

 fruit which ripens in the middle of July. 



313. Hypnum giganteum Schimp. 



* 



Amblystegiiim giganteum De Not. 

 Verv common. 



V 



Grows in bogs, where it is often the most abundant constituent of the 

 vegetation, especial!}* in the wettest situations, in channels and pools. 

 Near Akureyri it was common in bogs even at an elevation of 600 

 700 metres. Fruit, which occurs rather frequently, ripens in the first 

 half of July. 



314. Hypnum stramineum Dicks. 

 Amblystegiiim stramineum De Not. 



Very common over the whole of Iceland. 



It grows on damp ground, usually intermixed in tufts of other 

 Hypnum spp., Sphagna, Cinclidium , Mnium, etc. On very wet ground 

 it often forms pure extensive growths. Thus, near Ljosavatn, it grew 

 in the wettest parts of a bog at an altitude of 400 metres, in extensive, 

 richly fruiting mats, 1020 cm. deep. In depressions in the rocky 

 flat it forms in association with H. sarmentosum , H. revolvens and 

 H. exannulatam low, dense almost black growths. 



Fruit was ripe near Ljosavatn on July 18th. 



