992 



growtli is equally inipossible on account of the grinding action of 

 the finer particies driven by the storm. Gravel and pebbles are 

 consequently nearly always naked. 



The settlement of finer particies amongst the gravel and small 

 stones makes it possible for piants to grow there. This vegetation 

 may include phanerogams as well as mosses, if they are hardy 

 enough to maintain an existence on such barren piaces. The higher 

 and lower piants become allies, as it were, in a common effort to 

 gain ground, It may be that a small tuft of moss is the first out- 

 post on the bare gravel, and in this the seed of a phanerogam 

 takes shelter and germinates. When this seedling becomes larger 

 and more vigorous, it in turn becomes a stronghold from which 

 the moss may extend. Rather more frequently the phanerogam 

 comes first, and the moss follows later to grow in the shelter thus 

 provided. It is not always easy to tell which of these events has 

 happened. To some extent it depends on the species of phanero- 

 gam, some being capable of acting as pioneers, whereas others de- 

 velop hest in the moss-carpet. These less hardy species are not 

 true piants of the rocky-flat, strictly speaking, their home is in the 

 Grimmia-heath ; but as every little moss-carpet or even a small 

 moss-cushion may be said to be a diminutive Grimmia-heath, it is 

 rather difficult to decide where to draw the line. 



Some examples of the rocky-flat formation and its piants may now 

 be given. 



1. Sloping, stony rocky-flat on the so uther n side of 

 Skaalefjæld, Sydero, altitude about 375 m. above the sea. Here 

 and there small patches covered witli moss. On the open ground were 

 noted: Plantago maritima, Thymus, Armeria, Saxifraga stellaris (pyg- 

 maea), Polygonum viviparum, Ranunculus accr pumila, I^uzula spicata, 

 Agrostis canina, Festuca rubra, Arabis petraea, Koenigia, Silene acaulis, 

 Oxyria, Cerastium Edmondstonii, Aira alpina. 



2. The mountain above Karagjov near Kvalbo, Sydero, 

 altitude 265 m. The dominant piants on the plateau are Thymiis, Ar- 

 meria and Silene acaulis., others noted: Polygonum viviparum, Festuca 

 ovina vivipara, Cerastium Edmondstonii, Plantago maritima, Arabis pet- 

 raea, Ranunculus acer pumila, Festuca rubra, Luzula spicata, Koenigia, 

 Juncus trifidus, Alchimilla alpina, Thalictrum alpinum, Cerastium vul- 

 gare alpestre, Juncus triglumis, Empetrum, Viola silvestris, Alchimilla 

 filicaulis vestita, Agrostis vulgaris, Nardus, Selaginella, Saxifraga caespi- 

 tosa, Aira alpina, A. flexuosa montana, Saxifraga stellaris. 



3. Rocky-flat on top of K lakken, Bor do, altitude about 

 400 m. Species noted : Oxyria, Cochlearia officinalis (formå), Cerastium 

 vulgare alpestre, Saxifraga caespitosa, S. nivalis, S. oppositifolia, Arabis 



