DISSEMINATION OF SEEDS. 125 



pappus and remains attached to the rostrate or beaked 

 achenium ; this pappus is persistent, increases with the 

 ripening of the seed and, when the achenium with this 

 light downy appendage is removed by natural or artificial 

 means from the receptacle, it is borne hither and thither 

 by the wind until it reaches a resting place where it ger- 

 minates under favoring circumstances and, it may be, far 

 from the plant which produced it. 



Every breath of wind blows off the ripened seeds of 

 the dandelion and carries them to places far and near so 

 that we are not surprised that the weed is found "through 

 Europe and Asia, from Arctic latitudes to Algeria and 

 India, from Greenland to the Straits of Magellan ; in 

 Japan and New Zealand as well as in the Canary Islands ; 

 and on the Andes and Himalayas at an altitude of from 

 11,000 to 18,000 feet." 



The thistle, which has become naturalized to such an 

 extent as to have become in some parts of North America 

 a perfect pest, is furnished with a similar silky appendage. 

 When permitted to mature its fruit, the long spreading 

 pappus, very large in proportion to the size of the seed, 

 may be seen floating the achenia by hundreds through 

 the air and thus disseminating the intruder far and wide. 



JSrigeron Canadense, a very common weed furnished 

 with a similar pappus, was carried from America to a 

 botanical garden in Paris and Linnaeus said that " in less 

 than a hundred years the seeds had been so distributed 

 by the wind that it flourished in France, the British Isl- 

 ands, Italy, Sicily, Holland, and Germany." 



In an article on the distribution of plants, A. K. Wal- 

 lace says " When we consider the enormous quantity of 

 seeds produced by plants, that great numbers are more 

 or less adapted to be carried by the wind, that winds of 

 violent and long duration occur in most parts of the 



