WEEDS 107 



gives some idea of the viability of weeds and the vast num- 

 bers of seeds and species found in random samples of soil. 

 Lists of annual, biennial, and perennial weeds are given as 

 well as detailed descriptions of many species with a recom- 

 mended method of control. Many state experiment stations 

 publish valuable bulletins on the identification and control 

 of the common weeds of the state. 



Weeds are propagated chiefly by seeds, but many of them 

 have vegetative methods of propagation. Many weeds pro- 

 duce more than a hundred thousand seeds on a single plant, 

 which helps to answer the question, why so many weeds. 

 The seeds from a single plant may be widely scattered by 

 one or more of the common methods of dissemination. The 

 home gardener is most likely to get weed seeds from other 

 places by manure, by wind, by impurities with seeds, or by 

 animals (birds' excrement, or carried on the fur of cats or 

 dogs). 



Vegetative methods of weed reproduction most common 

 in perennials are mainly: by buds from underground roots, 

 or horizontal stems growing underground or close to the 

 ground and rooting at frequent intervals. Muenscher shows 

 some of the common weeds (Fig. 19) with buds growing 

 from a modified form of stem. Each bud may grow roots 

 and a new plant. The hawkweed, speedwell, and yarrow 

 send creeping stems along the surface of the ground to root 

 and grow new plants. Crabgrass grows horizontal stems 

 above the ground and morning glories have underground 

 stems with numerous nodes from each of which a group of 

 roots and a new shoot may grow. Hoeing may cut these 

 root-stalks into several sections, which if not removed will 

 each produce a new plant. The creeping plants are usually 

 so close to the soil that the lawn mower will not cut the stem 

 but may remove some of the leaves. 



Weeds can and should be controlled. In most cases it 

 requires less time and effort, year after year to control them. 



