194 DORIS LOVE 



among the North Atlantic islands only the Faeroes and Iceland harbor any 

 of these genera. 



A group of plants in Great Britain were believed to have been brought 

 attached to the bodies of the Pink-footed geese from North America via 

 Greenland to Ireland (Heslop-Harrison, 1953). Later, some of these taxa 

 have been shown to consist of different species on both sides of the Ocean 

 (Love and Love, 1958): Sisyrinchium august ifolium. In = 96 chromosomes, in 

 North America, 5". montanum, 2n = 32, in Greenland, Sisyrinchium hiberni- 

 cum, 2/7 = 64, in Ireland; Eriocaulon septangulare, 2n = 64, in Europe, 

 E. Parkeri, In = 32, and E. pellucidunu 2// 48, in North America (cf. 

 also Love and Love, 1961, and unpubl.), etc. The remaining species still 

 need further investigation in order to clarify their relationship across the 

 water. 



It seems thus, when closely considered, that there is a relatively small 

 chance for any large number of plants to have been dispersed by birds over 

 distances as great as the present ones between the North Atlantic islands. The 

 role of the birds as dispensers over shorter distances is no doubt much more 

 significant (Samuelsson, 1934) and they must have had a much more important 

 function if, at some time, these distances were shorter than now (Love and 

 Love, 1956; Dahl, 1958; Hadac, 1960). 



Based on a native flora of ca. 565 species (including ferns and fern-allies, 

 Juniperus, and Angiosperms except Taraxacum and Hieracium) in the Faeroes 

 (Rasmussen, 1952), Iceland (Love. 1945; Love and Love, 1956), Jan Mayen 

 (J. Lid, Oslo, pers. comm.). Bear Island (Ronning, 1959), Spitsbergen (Scho- 

 lander, 1934; Dahl, 1937; Hadac, 1944; Dahl and Hadac, 1946; Hagen, 1952) 

 and Fianz Joseph's Land (Hanssen and Lid, 1932), not more than at most 

 10 per cent can be referred to a category of plants which in recent (^ Post- 

 glacial) time possibly have been dispersed, internally or externally, by birds 

 (cf. also Table 2). 



Many plants are said to be dispersed by water, streams, currents, even 

 frozen in ice, etc. In most cases such dispersal takes place in fresh water, 

 which, however, in our area is of considerably limited importance. Except in 

 Iceland, there are virtually no rivers or lake systems which can possibly act as 

 transportation media. 



Long-distance dispersal by water in our area is therefore limited to the 

 carrying capacity of sea-currents, and thus at present only to the warm Gulf 

 Stream, and perhaps (though highly unlikely) to the cold currents around 

 Greenland and in the northernmost parts of the North Atlantic and the 

 Polar Sea. 



Few land plants have seeds which can stand immersion in salt water for 

 even a short time without losing both their buoyancy and germination 

 ability (cf. Salisbury, 1942), but there are seeds which can float for a long 

 time. CakUe edentula has such seeds, and this species has evidently been 



