533 



Again, it is obvious that plants which have evolved special organs 

 for an expansive distribution are those which will most likely be 

 carried to distant lands, because their seeds become mixed with 

 more varied material than those of the less prolific kinds, and arc, 

 in consequence, the more frequently introduced. It is for this 

 reason that many of the weeds introduced into Australia are 

 extremely aggressive. 



A number of people argue that, because some introduced weeds 

 furnish food to domesticated animals, they are not noxious. But 

 these people entirely overlook the fact that such compensation is 

 only one of degree ; for unless a plant is equal in value to the one 

 it has displaced there is a loss, which increases in proportion to the 

 rate the aggression extends. It may thus happen that a not entirely 

 useless but prolific plant becomes more noxious than one that 

 possesses no compensating qualities whatever, but which is less 

 prolific. Stock soon surfeit of plants found in great abundance, 

 because too uniform a pasture does not furnish every element for 

 their well-doing. The more variable the herbage, the better they 

 thrive ; consequently the poor pasture derived from introduced and 

 rapidly spreading weeds will never compensate for the loss of the 

 plants they suppress. At the best the professed compensation 

 derived from weeds is a poor consolation, and merely serves to hide 

 the indolence displayed over the neglect of their early eradication. 



Another excuse for neglecting an active destruction of weeds 

 is the assertion that if left alone they will disappear by themselves. 

 This may appear to be the case with a few species on very poor 

 soil, but it is then only at the almost complete exhaustion of the 

 same. Anyone who believes that by doing nothing against weeds 

 these will get " sick " of the soil, will have to wait a long time, and 

 then find that the devil was driven out by Beelzebub a more 

 noxious weed occupying the place of the first intruder, and in the 

 meantime the usefulness of the land has gone from bad to worse. 



A considerable number of exotic plants (upwards of 300 species) 

 have from time to time been introduced into Australia, many of 

 which have reached Western Australia. The most objectionable 

 hitherto introduced into our colony have been briefly described 

 in this chapter, as well as some of those which, having already be- 

 come specially noxious in the other colonies, may at any time 

 invade our lands. 



Some general remarks regarding the suppression and eradica- 

 tion of objectionable plants seem desirable. 



It is highly important to root out the invading plants imme- 

 diately after they have made their first appearance. Many at first 

 spring up in cultivated land or near homesteads, and therefore 

 become readily observable and, as a rule, can then easily be 

 mastered before they spread beyond control, which should be 

 taken advantage of. Too much stress cannot be laid upon the 

 necessity to destroy them before the seeds have ripened. But 



