Fróðskaparrit - 01.01.1993, Side 92

96 SALIX IN THE FAROE ISLANDS AND THEIR AFFINITY WITH THE POPULATIONS IN ICELAND
or S. glauca subsp. callicarpaea (Trautv.)
Boch. (Jalas and Suominen, 1976; Hulten
andFries, 1986). Argus (1965: 64-72 andp.
92) includes all these names in what he
calls “the eastem phase” of Salix glauca in
North America. In a field-handbook of the
Icelandic flora Love (1970) took up both
Salix cordifolia and Salix arctica and at
about the same time Skvortsov (1971) pub-
lished a paper about the Salices in Green-
land, Iceland and the Faroe Islands. There
he asserted that among the about 100 spec-
imens he had examined from Iceland two
were specimens of Salix arctica, two of
them were possibly hybrids, but all the rest
were S. glauca. That statement was fol-
lowed in an Icelandic Flora by Bjamason
(1983) and in two works about distribution
of plants (Jalas and Suominen, 1976;
Hulten and Fries, 1986).
Different from the situation in the Faroe
Islands the Icelandic population of Salix
arctica is very large. The species is almost
ubiquitous in the mountains and in the
northem districts of the country and are to
be found there in most plant communities.
At lower altitudes in the southem parts it is
only to be found near streams or wet places.
The habitats are very different and both the
morphological as well as the genetical vari-
ation within the population is enormous. It
is not always sufficient to draw conclusions
from several morphological characters on
herbarium specimens when distinguishing
related species within the genus Salix. Of-
ten it is necessary to compare whole popu-
lations and a good familiarity with plants in
their natural habitats is important. For sev-
eral years I have been studying the Ice-
landic population in field and cultivated ex-
perimentally pretty many individuals but
have never succeeded to fmd an aggregate
of morphological characters that makes it
possible to separate the population in dif-
ferent taxa. Notwithstanding an intemal
variation the main appearance of the popu-
lation is quite definite.
The population of Salix arctica in Ice-
land is similar to the population of that
species which I have studied at Mestersvig
in NE-Greenland. Comparing the Icelandic
population with the population in NE-
Greenland and herbarium specimens from
Arctic Eurasia and North America the same
morphological characteristics are to be
found although in different combinations
within the different specimens. On the
whole the high-arctic population from NE-
Greenland has not as tomentose leaves as
the Icelandic one, especially ecotypes from
wet habitats in the lowland. It is also neces-
sary to keep in mind that some of the char-
acters frequently used to distinguish Salix
arctica from S. glauca incline to change de-
pending on the environment. The blackish-
brown anthocyan-color that characterises
many plants growing in the high-arctic or at
high altitudes on northem latitudes is only
to be traced as faint reddish hue when the
plants are cultivated where ultraviolet radi-
ation is not so strong. Plants growing in
warmer and more humid climate produce
less waxcoat and whether the procumbent
branches are rooting or not depends highly
on edaphic conditions. What first of all
characterizes Salix arctica is procumbent
habitat with the branches trailing adpressed
to the ground where S. glauca is more or