The Botany of Iceland - 01.12.1930, Síða 98
88
H. M0LHOLM HANSEN
phorum polystachyum, and in the fétmýri Carex Lyngbyei. Of other
plants it is mostly Cyperaceæ which are found intermixed wilh
Equisetum palustre, thus species like Eriophorum polystachyum, Carex
Goodenoughii, C. rariflora, C. microglochin, C.capillaris, C. panicea,
and C. chordorrhiza, besides Scirpus cœspitosus. Other more conspi-
cuous plants are Polygonum viviparum, Thalictrum alpinum, Luzula
mulliflora, tíartschia alpina, Tofieldia palustris, Pinguicula vulgaris,
Selaginella selaginoides, and Equisetum variegatum; of Ch only Vac-
cinium uliginosum occurs with any noticeably high F.-percentage.
Locality No. 2 represents the typical, i. e. the most widespread
halla mýri formation; No. 1 is from a somewhat high level^ Nos. 4—5
from rather damp soil. If the water in the depression is stagnant,
Carex rariflora will be the physiognomical dominant (cf. No. 4), if
it contains running water, Carex Lyngbyei will dominate, perhaps
in company with Eriophorum Scheuchzeri (cf. Nr. 5). The two for-
mations can be recognised, even at a distance, by their colours, the
Carex rariflora formation by a darkgreen hue, the Carex Lyngbyei
formation by its yellowish green tinge. The surface differs from
the typical formation by being devoid of knolls.
Where springs are formed in the halla mýri, a moss vegetation
will develop. On this vegetation, the dý, Helgi Jónsson writes
as follows (1900, p. 25); — “the moss pools occur most frequently
at the foot of the mountains where the numerous springs appear;
here they pass imperceptibly into the mýri.” “The mosses which
seem to predominate are Philonotis fontana and Mniobryum albicans
v. glacialis.” “Scattered here and there in the moss carpet there
occur Epilobium alsinefolium, E. Hornemanni, Cerastium trigynum,
Montia rivularis, Saxifraga rivularis, Ranunculus hyperboreus, and
Catabrosa aquatica. In addition there occur Epilobium palustre, E.
lactiflorum, Eriophorum Scheuchzeri, Carex cryptocarpa, C. canesccns,
Eriophorum angustifolium, Equisetum palustre, Carex rariflora, Me-
nyanthes and Saxifraga stellaris.
The mosses are exclusively dominant; the intermixed species
are both few and far between.”
The fórmýri is only found at the bottom of the valley. An es-
sentiel difference between halla mýri and fórmýri is this that Equi-
setum palustre is lacking in the fórmýri, tíetula nana in the halla
mýri. The most conspicuous plants are Eriophorum polystachyum,
Vaccinium uliginosum, and Betula nana, further Carex Goodenoughii,
rariflora, saxatilis, and dioica, besides Polygonum viviparum and