The Botany of Iceland - 01.12.1945, Blaðsíða 22

364
STEINDÓR STEINDÓRSSON
individuals occur, as a rule at intervals of several metres. The fol-
lowing species were noted: Silene acaulis, Armeria vulgaris, Cerastium
alpinum, Arabis petraea. In the small depressions the plants grow a
little more close to each other, and Festuca rubra and Poa alpina occur
also. The small oasis Þorlákslindir lies on the bank of the river Kreppa
in a small pass in the ridge that extends along the river here. Two fairly
large rivulets issuing from springs empty into a lagoon that extends from
the river up into the pass. On the banks of the rivulets there is a narrow
rim of Scdix phylicifolia scrub mixed with herbs, of which Geranium
silvaticum and Archangelica are the most conspicuous. Otherwise the
greater part of the oasis is covered with growths of Juncus balticus,
while Salix heaths occur in the driest places, and Caiamagrostis neglecta
dominates in the damp depressions. The soil is very sandy, and the
vegetation has constantly to fight against the sand drift. Some vigorous
shrubs of Juniperus communis grow on the slope at the north side of
the pass.
3. Fagridalur is a fairly long valley which extends south-
eastward from the river Kreppa c. 20 km south of Arnardalur. South-
west of the valley lies Fagradalsfjall, a fairly high and steep
mountain, but otherwise the mountain ridges on either side of the
valley slope rather gradually. Through the valley flows a small river,
F agradalsá, into which some rivulets or streams empty from both
sides; several of them flow through large ravines, the rock walls of
which support a considerable vegetation in fissures and on ledges. The
bottom of the valley is level and comparatively luxuriant; various types
of mýri and flói vegetation are found there. These communities are
bordered by belts in which either Juncus balticus or Equisetum palustre
dominates. Salix heaths occur along the mountain sides. A small patch
of Elymus dunes is found in the southem part of the valley. Farther
towards the interior of the valley, on the side exposed towards the
southwest, fairly large Vaccinium uliginosum growths mixed with a
luxuriant herb vegetation are found, otherwise the mountain sides are
largely bare or with a very poor gravel-flat vegetation. However, stripes
of Philonotis fontana are found there along rivulets or in the grooves
excavated by them, which dry out in the summer.
4. Hvannalindir is an oasis situated on the spit of land
formed between Jökulsá á Fjöllum and Kreppa. A lava flow lies east
of the oasis, while west of it level sandy stretches extend as far as the