472 A. HESSELBO 



with everywhere on damp ground, often forming the bulk of the 

 vegetation, for instance in several places in NW. Iceland. It is, however, 

 also common in the more low-lying districts, where it grows especially 

 on damp soil along streams. 



Pohlia commntata is a most variable species, and occurs in Iceland 

 in numerous forms. The tufts are, as a rule, loose, and as much as 

 6 cm. high. In more particularly sheltered localities, for instance in 

 lava-clefts near Thingvellir, the plants are very vigorous, and form deep, 

 not-coherent tufts which are hardly tomentose. But in damp depressions 

 on the mountain heights they often form extensive, deep and dense 

 cushions which are brownish grey in the interior and yellowish green 

 only at the top; compact forms like this occurred abundantly on damp 

 gravelly flats, 400500 metres above Isafjordur. The single plants are 

 slender, with a thin fragile stem, and with leaves appressed, shortly 

 pointed, slightly toothed towards the apex and longly decurrent. The 

 leaf-cells are shorter, sometimes thin-walled, sometimes rather highly 

 thickened and porous, but both the form of the leaves and of the cells, 

 and the thickness of the walls may vary considerably in the same tuft 

 or even on the same plant. 



The fruit, which occurs rather frequently, was usually ripe at the 

 end of July. 



127. Pohlia gracilis (Schleich.) Lindb. 



Very common. 



In the lowlands this species grows, as a rule, on damp ground 

 along streams, either in unmixed tufts or, more often, associated with 

 Alicularia scalaris, Lophozia qiiinqaedentata, Cephalozia bicuspidata, Pohlia 

 commutata, etc. On cold, wet gravelly ground it is sometimes the most 

 abundant constituent of the vegetation; thus it was growing in enormous 

 quantity below 7 the "Jokull" in Kaldalon (NW. Iceland). In the Alpine 

 region from about 300 700 metres, Pohlia gracilis is one of the most 

 frequently occurring species, and grows everywhere on damp gravelly 

 flats, chiefly scattered among other mosses such as Anthelia Juratzkana, 

 Alicularia spp. , Polylrichum sexangnlare and Oligotrichum hercynicum, 

 more rarely in larger, unmixed growths. 



The fruit, which occurs very frequently, ripens on the mountain 

 heights usually at the end of July, in the lowlands a month earlier 

 (Kaldalon, June 22). 



128. Pohlia Rothii (Correns) Broth. 



Pohlia annotina (L.) Lindb. 



N. Iceland: Husavik JM; Stadr near Hrutafjordur !. 



It \vas growing in both places on damp sandy soil, associated with 

 Dicranclla crispa, Aonysti'ccmia lonyipes and Hepaticce. The gemmae, 

 which occurred only few in number, were quite typical. 



Webera annotina Hedw. is recorded from the peninsulas of NW. 

 Iceland (Stp.) and from Hafnarfjordur (Grl.), but as the collections con- 



