THE BRYOPHYTA OF ICELAND 489 



171. Mnium affine Blandow. 



Aslrophijllnm cuspidatum (L.) Lindb. 

 Very common. 



tj 



This species grows both in bogs, where it occurs everywhere and 

 almost always intermixed with other bog mosses, especially Hypnacece, 

 Cinclidhim sty y him and Mninm cinclidioides, and on the ground among 

 grass, as also on rocks. It is most frequent in the lowlands, and hardly 

 ascends higher than 400 500 metres above sea-level. ^ plants are very 

 common; on the other hand it has not been collected in fruit. 



It varies considerabl} T in habit, leaf-tissue and serrature of the leaf- 

 margin. In very wet localities the annual shoots become erect and the 

 stems often highly tomentose (var. elata Lindb.). On a more dry substratum, 

 especially on humus-covered rocks, the annual shoots are bent do\vn- 

 wards in a curve, and are rooting at the apex, and the fertile shoots 

 are quite short. The leaves are only very slightly or not at all decur- 

 rent. In the forms from a dry substratum the leaf-cells are rather 

 thick-walled, distinctly porous, and often collenchymatous; in bog-forms 

 they are more thin-walled and slightly porous. The teeth of the leaf- 

 margin are usually unicellular and obtuse, more rarely 2 4-cellular; 

 forms are very frequently met with in which the teeth are very slightly 

 developed or almost quite wanting, so that all transitions to var. inte- 

 grifolia Lindb. occur. The latter form is occasionally met with, especially 

 on rocks. 



172. Mnium Seligeri Jur. 



Astrophyllnm Seligeri (Jur. Lindb. 



E. Iceland: Hornafjordur!; Berufjordur! ; Seydisfjordur!; Vallanes 

 (H. J.)!. N. Iceland: Husavik!; Akureyri!; Ljosavatn!: Helgavatnsfloi St.)!. 

 W. Iceland: Stykkisholmur ! . Very common in SW. Iceland!. 



Grows on a very wet substratum, in marshes, moss bogs and along 

 streams, and often very abundantly. $ plants are almost always met 

 with; on the other hand, <$ plants or plants in fruit have not been 

 collected. 



M. Seligeri is one of the mosses of most common occurrence in the 

 south-western part of the country, from Hvalfjordur southwards, and 

 also about Hornafjordur; it often forms the bulk of the vegetation, for 

 instance in the great bogs in Olfus. In E. Iceland it is rather common, 

 and is also hardly rare in N. Iceland, but from NW. Iceland it appears 

 to be quite absent. It is easily distinguished from M. affine by its broadly 

 decurrent leaves, which are concave on the under surface. The leaf- 

 cells are, as a rule, somewhat smaller than in M. affine, 0.040.07 mm., 

 more thick-walled than in the latter species and decidedly collenchy- 

 matous; forms are, however, often found with thin-walled and somewhat 

 larger cells, which are then hardly to be distinguished from Mninm 

 affine \. elatnm except by the decurrent leaves. 



The Botany of Iceland. Vol. I, part II. 32 



