Rit Landbúnaðardeildar : B-flokkur - 01.05.1947, Blaðsíða 18

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in this connection, except perhaps the cases from Florida, West-Indies and
the Azores.
According to a number of scientists (cf. Rommell, 1938, p. 364 etc.;
Borza and Bujorean, 1927) seeds of different species are able to germinate
after a relatively long submergence in sea water, and seeds of some of the
species of plants native to our countrv have been found to be able to float
in sea water for several weeks or months. A good list of references to
papers dealing with the possibilities of dispersal of seeds by sea currents
is provided by Wulff (1943).
On the basis of the present studies on the distribution of Cakile
edentula it might be assumed that it has been dispersed from Ihe east
coast of North-America by the Gulf Stream. Its distribution in America
indicates a transport by sea currents and so does also its known distribu-
tion in places outside the American continent. The occurrence of the sub-
species ti/pica in Iceland and the Azores, i.e. the same subspecies as found
on the entire east coast of the North-American continent, is not easily
understood without the hypothesis of transport by the Gulf Stream.
The observations of previous writers may substitute the hypothesis
of dispersal of the seeds of Cakile edentula by the Gulf Stream. The seeds
of the closely related European species Cakile maritima have been found
to be able to float in sea water during some weeks (cf. Rommell, 1938).
And, according to the informations on the speed of the Gulf Stream given
by Sandström (1923—1937), the seeds might be able to float from Labra-
dor to Southwest-Iceland in 6 •— 8 weeks.
If the suggestion of the dispersal of Cakile edentula by the Gulf Stream
to Iceland and the Azores is correct, it might be possible that closer
investigation of Cakile from, e.g., the coasts of Norway and Ireland would
result in a discovery of the species in these European countries at least.
Some recent observations reveal that the Gulf Stream is able to trans-
port living matter from America to Iceland and the European coasts. The
variety of Zostera marina most common in East-America is var. steno-
phylla. It is the only variety of this species observed in Iceland. In 1932
and the following years a disease caused hy the Protozoa Lalnjrinthula
macrocystis Cien. (cf. Young, 1943) destroyed almost all plants of
Zostera marina on the coasts of Western Europe (cf. Blegvad, 1935;
Butcher, 1934; Cottam, 1935a,b; Fischer-Piette, Heim and Lami, 1932;
Lewis and Taylor, 1933; Petf.rsen, 1934, 1935; Prenant, 1934; Taylor,
1933). In 1932 or 1933 it was observed for the first time in Iceland (cf.
Friðriksson, 1936), but in eastern America it seerns to have been observed
in 1931 or 1932 (cf. Taylor, 1933; Lewis and Taylor, 1933).
At present, it is impossible to determine with full certainty the exact