— 132 — 
metre. This sand is more closely covered with vegetation 
than the clay, and two species are specially characteristic: 
Carex physodes (the aerial parts withered, but fresh buds 
present far down in the dense mat of old sheaths) and Arte- 
misia herba alba (a form of A. maritima s. lat.); the Carex is 
restricted to the sand-patches, the Artemisia occurs now and 
then on the bare clay. The following species likewise follow 
the sand: Haloxylon Ammodendron, small shrubs about 0,;—1 
metre high, Salsola sogdiana, Halimocnemis villosa, Halanthium 
gamocarpum, Cousinia dichotoma. Halimocnemis and Halan- 
thium are grey annual Chenopodiaceae (leaf-succulents) never 
found on deep dry sand; they are typical clay-plants, and 
along with the other plants mentioned, they occur here 
chiefly on the sand because it only formed a thin layer and 
thus created more favourable conditions by protecting the 
firm subsoil from desiccation (see above p. 80). 
There is a relation between the presence of the sand in 
this place and Carex physodes. It is very improbable that 
this sedge could originally have grown on the clay-surface 
and thus have caused the sand to become fixed. I never 
found it on clay, nor has any one else so far as I know, 
and it would not be in accordance with its mode of growth. 
The sand must have been present first, perhaps retained by 
stems of clay-plants, and then Carex physodes appeared — 
its vesicular spathes are easily transported — the stability 
of the sand being assured by its presence. More extensive 
investigations may perhaps decide this question, but my 
observations in this locality were very limited. 
9. Desert at Dana Shér Kala (“the castle of the wide- 
awake tiger”) on the left bank of the Amu Darya. June 27. 
1899. This locality (see also p. 76) lies west of the river, 
like Kara Aigir (No. 8) and the locality described next (No. 
10), so that there is very little sand. The desert is a stony, 
gravelly plain (coarse sand and small stones) with an exceed- 
ingly poor vegetation. The only species is Salsola rigida as 
small scattered shrubs with little heaps of sand round the 
base — a sign of sand-drift, but the sand does not remain 
lying. In one small valley, sand had accumulated and the 
