434 A. HESSELBO 



MUSCI VERI 



FAM. ANDRE/EACE^E. 



1. Andreaea 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 with right at the upper limit of vegetation, it often 

 descends upon the ground, even upon damp gravelly flats, where it 

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

 ways present. 



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

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

 specimens must be referred to A. petrophila. 



FAM. ARCHIDIACE.E. 

 2. Archidium phascoides Bridel. 



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

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

 hver!; Laugarashver !; Sydri Reykjahver!; Geysir!. 



Archidium phascoides occurs in the collections under different names. 

 It was first collected by Gronlund and determined by Zetterstedt 

 as Leskea nervosa. Afterwards this specimen with several others were 

 re -determined by Gronlund as Catoscopium nigritam var. Gronhmdii 

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

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

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

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

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

 to quite 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 

 Amblystegium compactum. The plant is typical of warm clay flats, and 

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

 warm clay flats with a temperature of 20 40, it forms extensive 

 yellowish-green mats 12 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, usually mixed 



