The Botany of Iceland - 01.12.1942, Page 66

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JOHS. GRONTVED
Festuca rubra
Cerastium alpinum
Carex rigida
Polygonum viviparum
Agrostis stolonifera
Juncus trifidus
Armeria vulgaris
Gentiana nivalis
Equisetum arvense
Galium pumilum
Phleum alpinum
Selaginella Selaginoides
Calamagrostis neglecta
Gnaphalium supinum
Euphrasia sp.
Kobresia Bellardi
Carex capitata
Pinguicula vulgaris
Thalictrum alpinum
A special form of highland heath is met with in several parts of
north-eastern and eastern Iceland, at a level of about 500 metres above
the sea. It is the Willow heath, characterized by the complete
dominance of the two Salix species, S. lanata and S. glauca. Both
species are here low and creeping, scarcely 15 cm high; growing densely,
they cover large stretches as with a carpet, only here and there with
small patches of Empetrum or cushions of Silene acaulis or Armeria
vulgaris. The soil is sandy and, during the summer, dry. Altogether this
type of vegetation is to be regarded as one of the driest of the formations
with a continuous plant cover (Humlum, 1936, p. 63).
Heather slopes with a vegetation of Empetrum, Vaccinium uligi-
nosum and V. Myrtillus are mentioned by Helgi Jónsson (1900, p. 70)
in his description of the Snæfellsnes vegetation. One of the two Vac-
cinium species may be dominant, or they may both occur in the same
quantity. Juniperus, Cassiope hypnoides and Loiseleuria procumbens
occur scattered, and many species of grasses and herbaceous plants play
a more or less important role.
Often the field layer of the more open birch wood and birch scrub
is actually composed of the species typical of the dwarf shrub heath,
and the dwarf shrubs thrive exceedingly well here (cp. also p. 62).
14. Scrub and Wood.
a. Willow Scrub. Although willows are widely distributed
throughout Iceland they rarely form actual scrub. In most cases they
occur more or less scattered in other formations (in birch scrub, in
heaths, fell field, mó and mýri).
Helgi Jónsson (1895 b, p. 36) mentions Salix scrub from E. Ice-
land (Víðirgróf and Bjarnastaóir), consisting of Salix phylicifolia
together with S. lanata and scattered specimens of Betula pubescens.
The average height of this scrub was about 80 cm.