The Botany of Iceland - 01.12.1945, Blaðsíða 143

THE VEGETATION OF CENTRAL ICELAND
485
Fig. 17. Flá in Hvannalindir. 1, Lake; Fig. 18. Flá in Háumýrar. 1, Lake; 2, Cala-
2, Calamagrostis neglecta-Kssoc., Belt I ; magrostis neglecta—Eriophorum Scheuchzeri-
3, Carex rufina-Assoc., Bclt 2; 4, Salix— Assoc., Belt 1 ; 3, Calamagrostis neglecta-
Juncus balticus-Calamagrostis-Assoc., Belt Assoc., Belt 2 ; 4, Carex rufina-Assoc., Belt 3 ;
3 ; 5, top of the rúst, sandy, wind-exposed, 5, Salix-Assoc., Belt 4; 6, Top of the rúst,
and nearly bare of vegetation, Belt 4. wind-eroded.
in belt 3. Its top is eroded by the vvind, and small cushions of plants
occur, of which Armeria vulgaris and Silene acaulis are the commonest.
Along cracks extending across the rúst there are narrow bands of plants
which have found a shelter in the depression formed along the crack;
otherwise the top of the rúst is a nearly bare flag.
Series 3 (Fig. 16 A) is from the centre of the same flá, where the
rúst is higher and steeper than the one whence series 2 is derived. Here
E. polystachyum dominates in belt 1 in company with Calamagrostis
and Carex rariflora. In belt 2 Calamagrostis and Salix glauca are do-
minants, but Carex rariflora and C. rigida are very conspicuous. Salices
are dominants in belt 3, especially S. lanata, but Calamagrostis, also, is
of some importance. Finally, Salix herbacea and S. glauca dominate
in belt 4 on top of thc rúst, in company with Elyna Bellardi, Armeria
vulgaris, and Silene acaulis. The vegetation of this belt is, indeed, open,
but still rnuch dcnscr than that of series 2, and the removal of soil by
the wind is accordingly less; altogether it would seem that the flá
is here at a more stationary stage than in series 2.
Series 4 (Tab. XXV, 4; Fig. 19) is from Sauðárdalur. There are