Náttúrufræðingurinn - 1964, Page 93

NÁTTÚ R U F RÆ i) 1 N G U RIN N
185
má deila um, hvenær tegund sé orðin algerlega ílend. Sum ræktuðu
erlendu skógartrén verða ef til vill fullgildir borgarar í gróðurríki
landsins, þegar tímar líða, t. d. sitkagreni, lerki o. fl. Þannig auðg-
ast landið að tegundum, og gróðursvipur þess breytist stórum.
Flestir eru slæðingarnir krossblómaættar eða 26, til grasaættar
(eljast 24, körfublómaættar 22 og 18 til ertublómaættar. Hinir til
ýmissa ætta, fáir til hverrar.
S U M M A R Y
Accidentally introduced species 1900—1963
by Ingólfur Daviðsson,
The University Research Institute, Reykjavík.
This paper deals witli all the species of vascular plants known to be acci-
dentally introduced to Iceland during the years 1900—1963. Stefánsson (1901)
reports 44 accidentally introduced species, 6 of whicli are now naturalized.
In the seconcl edition of his Flora, Stefánsson (1924) reports additionally 7
accidentally introduced species, hut 2 of them are now believed to liave grown
in he country from the very beginning of this century. In the third edition
(Stefánsson, 1948) 64 new accidentally introduced species are reported, this
increasing number without doubt being the result of the increasing com-
munication between Iceland and other countries, especially after 1940. 12 of
these 64 species are probaly naturalized now. Löve (1945) reports 2 accident-
ally introduced species not mentioned by Stefánsson. During the years 1948—
1963, additionally 52 accidentally introduced species liave been l’ound in lce-
land, 2 of which seem to being establislied in the country.
Summing up, 169 accidentally introduced species of vascular plants, all
listed in this paper, have been found growing in Iceland in this century; 26
of these species do belong to Cruciferae, 24 to Graminae, 22 to Compositae,
18 to Papilionaceae and the rest to other families, only few species to each.
25 of these 169 species can now be considered as firmly established aliens in
Iceland.
The history of sorne of these species in Icelancl is followecl and the alien
flora of some special localities discussed.
HEIMILDARIT - REFERENCES
Daviðsson, Ingólfur. 1949. Slæðingar í Reykjavik og grennd. Náttúrufr. 19:
133-135.'
— 1958. Landnámssaga gulbrárinnar. Náttúrufr. 28: 152—155.