IO WEEDS OF THE FARM AND GARDEN 



strike root at the nodes, or roots may be produced at the 

 joints, as in purslane. 



These roots and stems, capable of producing new 

 plants, are widely scattered in fields by means of the culti- 

 vator and plow. They may be dispersed with undecom- 

 posed manure, packing materials, or imported fruit trees. 

 Mice and gophers may scatter roots; to different parts of 

 the field. 



Character of Root Systems of Weeds. The root sys- 

 tems of weeds vary greatly. The term root, as ordinarily 

 used by the farmer, may mean a rootstock, as in the case 

 of quack grass or nimble will. A great many weeds, es- 

 pecially perennials, have not only perennial roots but 

 rootstocks also. A rootstock is simply a stem growing 

 beneath the surface of the ground. 



Many weeds have strong tap roots, this being especially 

 true of biennial weeds like the Canadian lettuce, mullein, 

 hemp, cocklebur, wild carrot, ragweed, prickly lettuce, 

 pigweed, mayweed, lamb's quarter, bull thistle, and field 

 thistle. The roots of many annual plants are fibrous and 

 without any distinct tap roots. Moreover they are shal- 

 low, like those in the buckhorn, foxtail, plantain, yellow 

 oxalis, and bootjack. The roots of plants in the same 

 order may differ greatly, but their general habit depends 

 a little on the character of the season. During moist 

 seasons they become quite shallow, while after the sea- 

 son becomes drier, they descend obliquely. The com- 

 mon spurge (Euphorbia Preslii) has a straight taproot 

 with horizontal roots near the surface of the ground 

 which descend obliquely later. The common field thistle 

 (Cirsium discolor) has a straight tap root with portions 

 frequently enlarged bearing several more or less promi- 

 nent lateral roots. 



The cocklebur, which belongs to the same family, has 

 a tap root which is considerably thickened near the sur- 

 face of the ground, and which has large lateral roots. It 



