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JOURNAL OF THE PLYMOUTH INSTITUTIOJT. 



the preceding remarks, and it is hoped that their bearing on what 

 follows will be clear. 



The following explanation of these three terms, together with 

 that of "JS'atives" (which is added that it might be contrasted 

 with the others), is taken from a work by one of our greatest 

 British botanists, Hewett Cottrell Watson : 



1st. A IS'ative. Apparently an aboriginal British species; 

 there being little or no reason for supposing it to have been first 

 introduced into this island by human agency. 



2nd. A Denizen. At present maintaining its habitats as if a 

 native species, without the direct aid of man, but liable to some 

 suspicion of having been originally introduced by human agency, 

 whether by design or accident. 



3rd. A Colonist. A weed of cultivated land, by road-sides, or 

 about houses, and seldom found except where the ground has been 

 adapted for its production and continuance by the operations of 

 man. 



4th. Alien species are those certainly, or very probably, of 

 foreign origin." 



With regard to many species it is extremely difficult to ascertain 

 whether they ought to be considered ISTatives or placed with the 

 Denizens or Colonists ; hence occasion is given for nice observation 

 or critical remark. 



Among the purposes for which our ancestors may be supposed to 

 have introduced various plants belonging to the denizen class are 

 for use as food for man or beast, for medicine, or for ornament. 

 In pursuing researches in this direction, the old popular names of 

 certain plants sometimes assist the student by referring to the 

 purposes to which the species bearing them were severally applied. 

 We know that in the Middle Ages the monks cultivated simples, 

 and the denizens that now cling to the walls of many monastic 

 ruins, or thrive best among their crumbling remains, are witnesses 

 of their practice of the healing art, and of the care they took to 

 provide medicines for the members of their fraternities and such 

 rustics as lived near their sanctuaries. Members of religious orders 

 who went on pilgrimage to other parts of Europe, or the more 

 distant Holy Land, might bring back with them roots or seeds of 

 foreign plants. 



The fact of a species being always found about dwellings, or in 



