THE MONTHLY BULLETIN. 469 



fruits of some fungi, such as the star fungi, also show hygroscopic 

 movement. The rays twist one way or the other with the change in 

 moisture and the spores are carried much farther than would otherwise 

 be possible. 



VEGETATIVE REPRODUCTION. 



In vegetative reproduction we have the rootstock, and the aerial root, 

 such as is found in ivy and in dodder. The aerial root in the case of 

 dodder is important. The dodder plant develops from seed but soon 

 separates from the ground and sinks small root-like organs into the host 

 plant. The best means of eradicating such a pest is to cut the crop, 

 dry and burn. The most important form here is the rootstock. We 

 can not be too particular when we deal with the eradication of a pest of 

 the rootstock class. One German botanist has even gone so far as to 

 classify all German weeds under two heads — seed weeds and root Aveeds 

 — so that no mistake could be made. Methods of control for these plants 

 are being worked out slowly. For some we already have proven methods 

 as. for example, wild morning-glory {Convolvulus arvensis). For 

 othei-s, such as Johnson grass, .sow thistle, Canada thistle, ancl quack 

 grass, we are not so sure the best method has been found. It is very 

 important in the case of these weeds to know with what you are dealing 

 when methods of eradication are tried. If a man tells you he has Can- 

 ada thistle on his place, see whether the weed has a perennial root ; if it 

 has not you will know at once that he is mistaken. 



ANIMAL AGENTS. 



I would like to go into a discussion of the types of rootstocks and 

 underground stems, but will have to hasten on to the even more im- 

 portant means of weed dissemination, namely : animal agencies, most of 

 which are under the control of the farmer, and should be under the 

 control of the quarantine guardian. 



The seeds of burdock, cocklebur. tarweed. bur clover and others are 

 scattered by cattle and horses. They catch in the fur of sheep, dogs 

 and other farm animals and are carried all over the farm. They are 

 provided with hooks, prickles, sticky surfaces, etc., to be carried in this 

 way. A great deal of trouble from weeds of this type can be prevented 

 by mowing the fence rows. It is hard to make the farmer see that his 

 stock will seed a clean pasture from a dirty fence row, but it is never- 

 theless true. 



Birds are also carriers of weed seeds and ofttimes they do considerable 

 damage, especially in carrying mistletoe seed from tree to tree. They 

 vvill also frequently carry small twigs loaded with fruits, such as the 

 black cherry, peppergrass, horse nettle and others; but on the whole 

 birds are more beneficial than otherwise, because they eat large quan- 

 tities of weed seed. The following quotations from the United States 

 Biological Survey are interesting on this point : 



"No less than fifty different birds act as weed destroyers, and the 

 noxious plants which they help to eradicate number more than three- 

 score species. Some of these plants are much more in favor than others, 

 while several are almost universally sought after. During the colder 

 half of the year food is furnished for many species of birds by well 

 known and widely distributed weeds." 



