

[Vol. 2 



100 ANNALS OK THE MISSOURI BOTANICAL GARDEN 



species generally immigrate singly and independently of one 

 another. 



It is not only man that assists in carrying plants across 

 large sea surfaces; the wind, ocean currents, and especially 

 birds from time to time transport seeds and other parts of 

 plants, which, under favorable conditions, continue to grow. 



I will not here go further into this complex question in its 

 entirety, but will refer to R. Sernander's ('01) detailed work 

 on the conditions for spreading in a great number of Scandin- 

 avian plants. I must, however, mention a few examples of 

 probable, or certain, chance distribution. At Vaage Lake, far 

 up the valley Gudbrandsdal, 990 feet above sea-level and 

 separated from the innermost fjords of the west coast by 56 

 miles of very high mountains, grows the typical sea-shore 

 plant, Elymus arenarius. That this occurrence represents a 

 relic is absolutely out of the question, for the sea cannot have 

 reached the height of Vaage Lake since the Silurian Period. 

 But I have seen gulls flying over the lake, and they may pos- 

 sibly have carried seeds with them, which have found a fnvor- 

 able soil in the long sandy shores. 



In 1837, Goleanthus subtilis was found upon a flooded river 

 bank a little north of Kristiania, and in 1842 a great number 

 of specimens were collected in the same locality, probably all 

 that existed there, for in spite of the most careful search for 

 a number of years, the plant has never subsequently been 

 found in that or in any other place in Norway. As its nearest 

 habitat is in Bohemia, it can only be supposed that some wad- 

 ing bird, in rapid flight from Bohemia to Norway, brought the 

 seed with it; and, furthermore, that as the seed fell upon 

 favorable soil, the plant grew up and had already begun to 

 spread when the collection was made in 1842. 



I have already ('05) endeavored to show that Campanula 



barbata, which occurs in a limited area on the mountains of 



central Norway, and is not again found until we come to the 

 mountains of Central Europe, cannot be a glacial relic, but 

 must have been accidentally introduced into Norway (by 



birds'?) in recent times. 



