THE SEED : ITS SELECTION AND DISTRIBUTION 49 



away, as we would a bean with a bent stick. Still other 

 seeds, such as those of the wild oat, actually work their 

 way along the ground in a sort of creeping motion. 



37. How Seeds are scattered by Man. — Man has 

 played an important part in scattering seeds from state 

 to state and from one part of the world to another. Very 

 few of our noxious weeds are natives of America, most of 

 them having been introduced by 

 man from foreign lands. The 

 quack grass, the docks, the 

 Canada thistle, Russian thistle, 

 pigweed, foxtail and many others 

 were not found in this country 

 when the white man first began 

 to settle here. Man scatters seeds 

 of weeds (1) in commercial seeds, 

 (2) from railway and trolley 

 cars, (3) in wool and hay, (4) in 

 manure, and (5) in the packing 

 about goods and nursery stock. 



Many of the grains, grasses, 

 trees and shrubs which grow 

 in our fields and about our homes were first brought 

 to us from foreign countries. Of the following plants, 

 — corn, wheat, oats, red clover, alfalfa, timothy, blue grass, 

 cotton, apples, peaches, pears and oranges, — corn alone 

 originated on this continent. New varieties of seeds, 

 as well as those which have long grown here, are being in- 

 troduced each year from foreign countries. The aimual 

 shipment of seed from state to state is enormous. The 

 shipper may fail to clean his seed properly. Commercial 

 seeds, therefore, become the carriers of weed seeds. 



Almost every year, some new variety of plant springs 



Fig. 16. — Explosive seeds: 

 the squirting cucumber. 



