Biennials. — Are those plants wliicli require two seasons to complete 

 their growth, the first being spent in collecting and storing up a supply of 

 nourishment, which is used the second season in producing flowers and 

 seeds. Examples of these are Burdock, False-tansy, Common Evening-prim- 

 rose and Viper's Bugloss or Blue-weed. 



Perennials — Are those plants which continue growing for many years. 

 Perennial weeds are propagated in several ways, but all produce seeds as 

 well. They have two distinct modes of growth, those which root deeply, and 

 those of which the the root system is near the surface. The most trouble- 

 some are those which extend long underground stems deep beneath the sur- 

 face of the ground, as Canada Thistle, Perennial or Field Sowthistle, Field 

 Bindweed, Bladder Campion, White-stemmed Evening-primrose, Showy Let- 

 tuce, and some wild Sunflowers. Representatives of the second class or shal- 

 low-rooted perennials are : Pasture Sage, Yarrow and Couch Grass. Some 

 perennials extend but slowly from the root by means- of short stems or 

 offsets, but produce a large quantity of seed. Of these, Ox-eye Daisy, Dan- 

 delion, Goldenrod and Yarrow are examples. 



Extermination of Weeds. 



In adopting a method of extermination, the nature of the plant to be 

 eradicated and its habits of growth must, first of all, be taken into considera- 

 tion. 



Annuals. — Any method by which the germination of the seed in the soil 

 is hastened and the young plants afterwards destroyed before they produce 

 fresh seed, must in time clean land however badly infested it may be with 

 annual weeds. The seeds of some annuals have great vitality, and will con- 

 tinue appearing for several years as fresh seeds are brought up to the surface 

 by cultivation. Wild Mustard seeds have been known to germinate after 

 lying deep in the ground for twenty years, and the same vitality has been 

 claimed for Wild Oats, with, however, less satisfactory evidence. 



Biennials must be either ploughed up or cut down before they flower. 

 Mowing at short intervals in the second year, so as to prevent the formation 

 of new seed, will clear the land of this class of plants; but a single mowing 

 will only induce them to send out later branches, which, if not cut, will 

 mature many seeds. Where ploughing is impracticable, this class of plants 

 should be cut off below the crown of the root. For this purpose, a spud or 

 a large chisel at the end of a long handle (to obviate the necessity of stoop- 

 ing) is as convenient a tool as can be used. 



Perennials are by far the most troublesome of all weeds and require 

 very thorough treatment, in some instances the cultivation of special crops, 

 to ensure their eradication. Imperfect treatment such as a single ploughing, 

 frequently does more harm than good, by breaking up the underground stems 

 and stimulating growth. 



It will be found in examining several perennial plants that they may 

 be divided into two classes, one of which has its root svstem close to the sur- 

 face of the soil, while the other roots very deeply. For the shallow-rooted 

 perennials, infested land should be either trenched deeply or ploughed so 

 lightly that the roots are exposed to the sun to dry up. For deep-rooted per- 

 ennials, on the other hand, ploughing should be as deep as conveniently pos- 

 sible without going to extra expense. The depth of ploughing must be de- 

 cided by the nature of the land. In light or gravelly soils shallow ploughing 

 may be preferable, as too deep ploughing would interfere wifli Ihe mechanical 

 texture of the soil, which is so important in the movement of soil moisture. 



