22 CARL SKOTTSBERG, (Schwed. Südpolar-Exp. 
Especially instructive was a place on the south side of Pot Harbour, where a small 
stream crosses the Poa-fringe, which over a large stretch has been changed into a 
Polytrichum-bog (Fig. 4) where Pogonatum alpinum occurs with enormous, firm 
cushions, up to 3 or 4 m. in circumference and 3—5 dm high. Zoa-tussocks in all 
stages of destruction are seen here, more or less overgrown with Pogonatum. Some 
of the cushions only show some tufts of the grass at their margin; I made sections 
through two of them and found the remains of the killed grass in their centre. 
I also cut through two pure Pogonatum-cushions, both containing a dense mass 
of grass-peat. Between the cushions, in the wet depressions, grows the Rostkowia- 
association. 
I am convinced that we once had a Poa-community on this spot. The only 
reason for its destruction that seems-to suggest itself is that the stream, which winds 
over level ground and is much branched, has been shifting its course a little for 
the last ten or twenty years. That this space of time is quite sufficient for the 
Polytrichaceae to attain a considerable size was clearly shown by a visit to Dr. 
WILLS old garden at the German station in Royal Bay, where 20 years before our 
visit certainly no Polytrichum or Pogonatum at all existed; his plantbeds now were 
overgrown with those mosses. 
2. The vegetation of the rocky shore. 
In all the coves and harbours mentioned in this paper, steep rocks come down 
to the water in many places, mostly covered only with crustaceous lichens, but of- 
fering some crevices and small shelves as a refuge to phanerogams and mosses. 
Even here Poa flabellata grows, mostly in small tufts, together with the few plants 
especially characteristic of such places. The most noticeable is Colodanthus subu- 
latus, forming small, more or less globose cushions or filling up narrow crevices. 
It is nearly as hard and compact as an Andine Azorella. In such places is also 
found the small Zymenophyllum falklandicum, very densely matted. 
The moss vegetation will be illustrated with the following examples. 
May Cove: Bryum lamprocarpum Dicranoweisia grimmiacea. 
Orthotrichum crassifolium. 
Jason Harbour: Orthotrichum crassifolium Willia grimmioides. 
Moraine Fjord: Aneura cochleata Webera implexa v. nigrita n. var. 
Royal Bay: Dicranoweisia grimmiacea Orthotrichum crassifolium 
> subinclinata  FPottia austrogeorgica. 
