434 A. HESSELBO 



MUSCI VEHI 



Fam. ANDREÆACEÆ. 



1. Andreæa petrophila Ehrh. 



Very common all 'over Iceland. In the lowlands it grows in small 

 round cushions on blocks and on rocks in dry situations and in such 

 localities it is often the dominant species. On mountain heights, where 

 it is frequently met witli right at the upper limit of vegetation, it often 

 descends upon the ground. even upon damp gravelly flåts, where it 

 forms extensive cushions almost black in colour. Fruit is almost al- 

 ways present. 



Note. Andreæa rupestris L. = A. Rothii W. M. is recorded by Morch 

 from Iceland and is figured in Flora Danica, tab. 2125, but Morch's 

 specimcns must be referred to A. petrophila. 



Fam. ARCHIDIACEÆ. 

 2. Archidium phascoides Bridel. 



W. Iceland: Reykholtdalur!, near all the hot springs (Grl. ;1); Englands- 

 hver!. S. Iceland: Reykirdalur !; Reykjanes (Ostf.!; Kolvidarhol ! ; Thorlåks- 

 hver!; Laugaråshver !; Sydri Reykjahver!; Gcysir!. 



Archidiam phascoides occurs in the collcctions under different names. 

 It was first collected by Gronlund and determined In' Zetterstedt 

 as Leskea nervosa. Aftcrwards this specimen with several others were 

 re -determined by Gronlund as Catoscopium nigritum var. Gronhindii 

 established by C. Jensen. All the piants collected by Ostenfeld 

 from Reykjanes are determined by C. Jensen as Pohlia niitans v. 

 filicaiilis. The reason for all these erroneous determinations will be found 

 in the faet that the plant is almost always found barren and in leaf- 

 form and cell-tissue presents a certain resemblance to mosses belonging 

 to (juite different groups, which often leads to the belief that the spe- 

 cimens in question are stunted forms or have been affected by the warm 

 substratum: thus, certain forms bear a striking likeness to a slender 

 Amblysteginm compactiim. The plant is typical of warm clay flåts, and 

 in S. and W. Iceland it is met with around every hot spring. On the 

 warm clay flåts with a temperature of 20*^— 40*^, it forms extensive 

 yellowish-green mats 1—2 cm. high. On slopes stretching down towards 

 the boiling water and along outlets from the springs it is also frequently 

 found growing within a few centimetres from the water, usuall}' mixed 



