The Botany of Iceland - 01.12.1942, Blaðsíða 11

THE TARAXACUM-FLORA OF ICELAND
237
terial of the species of which I only had a small number, partly to
secure live material for a further comparison of the numerous species
with each other and with the Danish species (which I was also cultivat-
ing). For a garden I used a plot of meadow which proved good for
the purpose. The plants grew well with the exception of a small number.
The spring of 1937 was very wet, and in the beginning of the season
my Taraxacum-garden was partly flooded. The Icelandic Taraxacum-
species developed beautifully, and flowered very abundantly, but one
or two weeks later than the Danish species. The spring of 1938, on the
contrary, was rather dry, and this influenced the Icelandic Taraxaca
very much; they did not by far develop like those of the previous year.
Now I let the Taraxacum-garden take care of itself to see whether any
of the Taraxacum-species were able to compete with the natural, Danish
vegetation invading the garden from the meadow; but they were not
able to do so. Very shortly Danish plants, mostly grasses, among others
Holcus mollis, invading the Taraxacum-garden crowded out all the
Icelandic Taraxaca. Already in the spring of 1939 few were left, and
in the autumn of 1939 it was not possible to find a single Icelandic
T araxacum-plant.
The Taraxacum-fruits collected in the year 1937 were sown in the
spring of 1938, and the young plants were planted out in my garden in
Koge, Denmark. The garden is rather low, the soil very sandy, and
there is shade during a great many hours of the day. Several of the
Icelandic Taraxacum-sptdes grew well in the sandy and rather dry
garden, whereas others did very badly. In the spring of 1939, however,
they were all flowering, but many species were small and slender and
quite untypical, and later in the summer these especially were attacked
by mildew, several of them dying. Neither soil nor climate were, ap-
parently, suitable for them. The time of flowering was now even later
than previously. It was curious to see how late the development of the
spring rosettes began, in spite of the temperature here being higher
than that under which the same species developed in their native
country. They seemed inclined to prolong the long winter-rest.
During the cultivation I took the opportunity of making castration-
experiments on many of the Icelandic Taraxacum-species. These experi-
ments were successful in all cases. In spite of the operation the young
achenes grew to be fruits with germinating power1. It would seem,
11 Owing to illness I was not able, however, to collect the fruits which developed
in spite of castration, nor had I made a list of the species castrated; but, as men-
tioned above, in no case did the development of the fruits stop, in spite of the
operation.