The Botany of Iceland - 01.12.1945, Page 106

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STEINDÓR STEINDÓRSSON
silvaticum. Some individuals of Archangelica are found here and there.
The biological spectrum shows a high E percentage, the E^ percentage,
in particular, is high. Although I did not take more analyses from
this association, it is found here and there within my area of investiga-
tion under similar conditions as in Þorlákslindir, that is to say, along
the banks of brooks issuing from springs, where there is shelter and
the snow-covering is comparatively thick. It never covers large areas,
but forms narrow belts along the brooks. The association is particularly
frequent in Hvannalindir, where the brooks have fairly high banks.
The following species were noticed in this association in Hvannalindir:
Salix phylicifol'a (The specimcns brought home, which I determined as
S. phylicifolia, on closer inspection by Dr. B. Floderus was found
to be the hybrid S. phylicifolia X S. glauca. I am inclined to think that
it is precisely this hybrid which forms this Salix scrub everywhere, both
in Hvannalindir and in Þorlákslindir, and that the main species is
either not found there or is very rare. However, the hybrid from these
localities bears a much greater resemblance to S. phylicifolia than to
S. glauca). In addition: S. lanata, S. glauca, Epilobium alsinifolium,
E. latifolium, Archangelica officinalis, Festuca rubra, Poa alpina,
Phleum alpinum, Polygonum viviparum, Juncus balticus, Calamagros-
tis neglecta, Carex incurva, Equisetum arvense, E. variegatum, Salix
herbacea, and Deschampsia alpina. These are Iargely the same species
as occur in Þorlákslindir. Anderson & Falk describe this as-
sociation from Hvannalindir as Zone D (1. c. 412). Where the banks of
the brook are low, the tall Salix shrubs disappear, while Archangelica
will dominate physiognomically, intermixed with the creeping Salix
glauca.
10. Salix phylicifolia—S. glauca—Anthoxanthum odoratum-Ass.
(Tab. XV. A-B, 10).
Only one analysis is at hand from this association, which, like the
preceding one, should more correctly be called a coppice than a heath.
The analysis was made in Víðidalur, at an altitude of c. 420 m. Thus
according to its situation it hardly belongs to the other associations,
since they were chiefly found above an altitude of 500 m. The Salix
shrubs are fairly tall here, 60-90 cm. The ground vegetation is very
dense. In addition to the character species the following dominants are
found: Carex rigida, Festuca rubra, Polygonum viviparum, and Tha-
lictrum alpinum. The association is found in sheltered places, where