31 



this babit are wonderfully tenacious and are the raost difficult to 

 eradicate. Golden hawkweed is propagated by runners similar 

 to the strawberry, and the Canada thistle by running roots. 

 These methods of propagation are, however, merely accessory 

 methods. 



The most universal method of plant propagation is by seed, and 

 the many ingenious ways in which plants are able to disseminate 

 themselves is remarkable indeed. One could hardly have ever 

 seen a dandelion without having observed the admirable seed 

 apparatus, the seed being constructed especially for being wafted 

 by the wind. No less interesting as wind propagators are prickly 

 lettuce, milkweed, Canada thistle and fire-weed. 



Another method of seed propagation common to some weeds is 

 by animals. Many plants, such as the pokeweed, have berries 

 which are eaten by birds, and as most hard seeds are not digested 

 by them they are dropped here and there. If conditions are 

 favorable they will readily develop. Many seeds eaten by horses 

 and cattle are not impaired, and in this manner many weeds find 

 new abodes. Then again we find curious devices connected with 

 seeds for attaching themselves to animals. There are many of 

 these devices ; one of the best known plants among us which has 

 acquired this habit is the burdock. 



Through this acquired habit in seeds many plants are introduced 

 into our State every year through wool importation. Fortunately, 

 however, these plants are mostly confined to dump heaps about 

 mills, and many of them at the present time have not gained 

 much foothold in Massachusetts. Other sources of weeds are 

 found in the importation of commercial seeds. 



In oat and rye fields are the wild mustard (Brassica sinapis- 

 trtim), chess or cheat {Bromns secalinns) and many other plants. 

 One of the most impure seeds is that of red clover. The weed 

 seeds most common in clover are rib-grass { Plantago lanceolatd) , 

 sorrel (Rumex acetosella), and pigeon-grass (Setaria glauca). 

 The seeds of white cockle, ragweed, prickly lettuce, pepper-grass, 

 Canada thistle, ox-eye daisy and wild carrot are not infrequent, 

 while those of the dandelion, etc., are often found. 



Occasionally weeds as well as injurious insects and fungi are in- 

 troduced with nursery stock. 



Hay furnishes an excellent medium for the introduction of various 

 weed seeds, and some of our numerous weeds owe their origin to 

 the introduction of baled hay. Much of the glassware and 

 crockery imported from Europe is packed in haj^, and here we have 

 a constant source of contamination. This hay is frequently used 

 a number of times for packing purposes and is distributed to vari- 

 ous parts of the country. 



