254 



Weeds. 



(Lychnis Githago) often gets into wheat fields; white daisies, plantains 

 and buttercups, into meadows. Another fruitful source of infection 

 is found in the manure that is spread upon the fields. The seeds of 

 many weeds pass through the alimentary canal of horses and cattle, 

 undigested and unharmed. From these seeds the weeds of the fields 

 to which the manure is applied grow; they are cut and cured with the 

 hay, fed to the live stock and again the pernicious seeds go to the 

 fields to defile the hay and perpetuate the evil. 



Some weeds find their way into the fields by the agency of the 

 winds. Their seeds have a spreading downy appendage that helps 

 sustain them in the air while the Avind wafts them along to some dis- 

 tant resting place. The dandelion seed is an example of this kind. 

 Other seeds, like those of the common silk weed (Asclepias Cornati), 

 not only have the downy buoyant support, but also a winged margin 

 that catches the wind like a sail and so aids in the propulsion of the 

 seed through the air. Others still, like beggar ticks (Bidens fron- 

 dosa) and Spanish needles (Bidens bipinnata) are furnished with 

 downwardly barbed appendages by which they cling to the clothing 

 of men and the hair of animals, and in this way they sometimes 

 steal a ride into the fields. In the burdock (Arctium Lappa) and 

 the burgrass (CencJirus tribuloides) the seeds are encased in an in- 

 volucre armed with hook-tipped spines, by which efficient instru- 

 ments of attachment they gain transportation in companies sufficient 

 to form families or colonies of weeds. 



Railroads are active agents in transporting weed-seeds from place 

 to place. Plants that are evidently new importations from other 

 localities are sometimes found along the lines of railroads. They are 

 brought with freight, with loads of grain, by passengers, or are repeat- 

 edly whirled along by the rush of air that follows each fast moving 

 train. It is said that in Kansas it is not uncommon to see peach trees 

 growing wild along the sides of the railroads. The passengers eat the 

 peaches while traveling and throw the pits from the car windows. 

 The soil and climate being favorable to their growth, the trees tell 

 the story of their origin. Such are some of the ways in which weeds 

 are introduced. 



This leads us to the consideration of some of the characters 

 which belong to weeds and which enable them to become troublesome. 

 Among these are great tenacity of life, vigorous, rapid growth, great 

 power of seed production, longevity of seed, adaptation to varying 

 conditions in soil, season or climate, and especially a strong root 

 growth or its equivalent, a vigorous growth of subterranean stems. 



