The Botany of Iceland - 01.12.1942, Page 62
60
JOHS. GRONTVED
Transitional stages to fell-field vegetation on the one hand, and
heather moor, copses, etc. on the other hand, may be met with every-
where.
12. The Mó Vegetation.
A series of vegetation types are included by Molholm Hansen (1930,
p. 47) under the designation “The Mó Vegetation”. This term is, ac-
cording to M.H., used for “all such formations as are normally covered
with snow in the winter, whose degree of moisture is exlusively deter-
mined by the precipitation, not by the ground water, the soil of which
is not covered with forest or copsewood”.
As M.H. remarks, the mó will thus comprise Helgi Jónsson’s forma-
tions: heath, heather mó, grass mó, dwarf willow (in part), and grass
field (in part).
In the following we will deal with the mó vegetation as classed
by Helgi Jónsson under the heading grass mó (in a broader
sense) and heather mó (cp. H.T., 1895 b, p. 36 & p. 59—64;
1900, p. 63 & p. 70).
The grass-mó (in a less restricted sense) is described by H.J. as
dry, very knolly stretches of land where the characterizing species are
Gramineae, Juncaceae and Cyperaceae. These stretches are of a very
variable appearance, usually showing a marked difference between the
vegetation of the knolls and that of the depressions between them. It
is generally the species growing on the knolls which lend its special
aspects to the mó vegetation.
According to the dominating species in the grass mó vegetation
several types may be distinguished. Thus Helgi Jónsson (1895 b, p. 59
et seq.) describes three types from E. Iceland, viz. Kobresia mó (Elyna
mó), Juncus mó, and Grass mó.
a. In the Kobresia mó the vegetation on the knolls is charac-
terized by Kobresia Bellardi and Juncus trifidus while Salix herbacea
and lichens (Lecanora, Biatora, Buellia and others) often fill out the
spaces between Kobresia and Juncus.
In addition the following species occur:
Silene acaulis
Dryas octopetala
Thalictrum alpinum
Polygonum viviparum
Cerastium alpinum
Campanula rotundifolia
Luzula multiflora
Luzula spicata
Potentilla Crantzii
Selaginella Selaginoides
Pinguicula vulgaris
Tofieldia palustris
Thymus Serpyllum var.
Galium verum