RAILWAYS AS CARRIERS OP WEED SEEDS. 9 



cilage which causes them to adhere to every passing object. Live 

 stock taken from one farm or one locality to another often carry 

 many of _ these seeds or burs in wool, manes or tails, and many a 

 clean farm has from this cause suddenly produced crops of weeds 

 whose origin doubtless puzzled and dismayed the owner. The 

 parts of seeds or fruits which have been evolved as clasping organs 

 are thus seen to be varied in form &nd structure, but each has 

 enabled the plant to which it belongs to migrate time and again 

 to a new home where it could the better tight the battle of life. 



Man as an agent of seed distribution. — The plants which 

 have become the most successful weeds of the farm have had their 

 seeds spread more widely through the agency of man than through 

 all other methods combined. His roads and trails wind everywhere 



Fig. 1. HLstrating methods of Heed distribution: a, seeds (achenes) of dandelion with pappup attached, 

 several of them still borne on the receptacle: h, fruit of beggar-ticks showing the barbed awns; c and d, burs or 

 fruits of cocklebur and burdock, showing the grappling appendages; e, fruit of wild carrot, showing the clutching 

 spines; /, winged fruit of wafer-ash. (After Kerner and Beal.) 



through plain and forest; his railway lines bind every State to- 

 gether and connect with steamship lines from across the seas, and 

 along all these avenues of commerce weed seeds are constantly 

 travelling, sometimes as paid passengers in company with grain 

 and other farm seeds, but more often as hoboes in hay, bedding, 

 packing, shipments of fruit, etc. 



The great east and west trunk lines of railways are responsible 

 for the wide distribution of many a weed, such as the Russian 

 thistle, prickly lettuce, Canada thistle and Texas nettle, which 

 first appear in any locality along a railway. The seeds are carried 

 either in the coats of cattle or sheep, in the hay which supports 

 them on their journey, or in the bedding on the floor of the car. 

 Dropping at intervals all along the line the seeds find excellent 



