34 



affected the existence of introduced plants in any locality, one would 

 suppose that it was due to some quality peculiar or characteristio- 

 of the seeds themselves; and this would be, possibly, the line of 

 thought which the mind would naturally at first entertain. Upon 

 examination, however, we are almost startled to find that all the 

 wonderful appendages and beautiful contrivances^ for the distribution 

 of seeds, such as the copious pappus of the Compositfe, the silk of 

 the Epilobium and Asclepias, the spinous, and hooked seeds of the 

 Borraginaceaj, the attractive esculent fruits and mucilaginous cover- 

 ings of some seeds as well as the buoyant qualities of the seeds and 

 seedjiods of certain plants, have little or no effect on the general question 

 at large of the distribution of genera and species of plants over th& 

 surface of the globe. It is not so much a question of getting a seed to 

 a certain locality, but of its survival when brought there. 

 DeCandolle has worked out this idea in a masterly manner, in his 

 " Geographic Botanique," and shows from statistics that the inherent 

 qualities of seeds and their receptacles only apply for their distribution 

 in the localities or countries where the plants are indigenous. He 

 draws attention to the fact that many of the plants which apparently 

 have the most perfect contrivances for their ti'ansmission from one place 

 to another have an exceedingly limited range, while others with no 

 such appendages are much more widely distributed. 



The following lists give all the introduced plants which up to the 

 present time have been found in this locality. I am of opinion that 

 the divisions proposed will be found convenient for the botanical student » 

 List No. 1, Aggressive Weeds, gives the names of all those plants which 

 are so well established as to require constant attention on the part of 

 the husbandman to keep them in check. It will be noticed that some 

 of the names are in italics, this is meant to denote that, although the 

 plant is introduced, it is probable that it also existed here before 

 that time as an indigenous plant. No. 2 embraces those plants, 

 which, having been introduced, are gradually spreading over the 

 locality, but are not yet sufficiently numerous to have become aggres« 

 sive weeds. Of these the two Erodiums and Datura Tatula are 

 interesting examples which were first grown here as Botanical specimens 

 in 1881, but are now to be found in waste places all over the city. 



