WEEDS AND WEED SEEDLINGS. 



27 



accidentally buried in a bed on which seeds were sown ! All such 

 troublesome plants, cultivated or wild, are strictly weeds," but we 

 have confined our attention here to the wild Flora. 



Weeds are annual (or ephemeral), biennial, or perennial, and we 

 may take it that roughly the difficulty of eradicating a given weed 

 varies according to the group to which it belongs — though not in- 

 variably so. Annuals are reproduced from year to year by seed, the 

 plant living one season only, while some species (chickweed, ground- 

 sel) which give rise to several generations in a year are known as 

 ephemerals ; biennials become established from seed .one year, and 

 flower, seed, and die the next ; and perennials survive for a number of 

 years varying with the species, in general producing seed each year, 

 and. often extending also by means of creeping rootstocks. 



How Weeds are Spread. 



Weeds are distributed by many agencies. Annuals and biennials 

 depend for their distribution on seed, and these classes produce enormous 



Fig. 1. 



a, Rootstock of Couch {Triticum repens L) ; b, Rootstock of Great Bindweed 

 {Convolvulus sepium L.) ; c, Roots of Creeping Thistle {Cnicus arvensis 

 Hoffm.). AH X i- 



quantities of seed, often many thousands on a single plant. The 

 perennials are not so dependent on seed, and produce less, but such 

 plants as couch, creeping thistle, bindweed, and coltsfoot have exten- 

 sively creeping rootstocks by which they insidiously extend beneath 

 the soil, while broken pieces of these rootstocks are often carried on 

 implements and dropped where they may start a new centre of infesta- 

 tion. (Pig. 1.) 



