558 NATIVE AND NATURALIZED BRITISH SPECIES. [Jime, 



only been known in this country for a very short period, conse- 

 quently we may say it is naturalized. But when we include under 

 this category Vinca minor, Chelidonium majuSy Cheiranthus Cheiri, 

 Linaria Cymbalaria, and many other equally common and well- 

 established plants, what value is the term alien or naturalized ? 

 The plant against which it is placed may have been the sponta- 

 neous production of the country for a hundred years or a thou- 

 sand years. Nay, we have no historical evidence of its introduc- 

 tion at any time ; it may be native, or it may have been intro- 

 duced before the Flood, for anything we can tell. 



Great importance is very properly attributed to the terms 

 native and naturalized ; the latter (see ' Phytologist,' p. 450, as 

 above) is defined to have " every appearance of a native, growing 

 and reproducing itself regularly, without the assistance of man ; 

 proved to be acclimatized by having survived for a period of 

 years, embracing all the varieties of temperature." To ascertain 

 if a plant be native, a character obviously distinct from natu- 

 ralized, De Candolle, in his ' Geographic Botanique,^ employs 

 three tests : — 1st. The old Floras are examined to see if the 

 species in question was entered in them as an undoubted native. 

 2nd. The names in popular use are to be compared, to see if 

 it had a name in the older language of the country where it is 

 now found; and 3rd, the botanical proofs derived from the na- 

 ture of the habitat, whether in the vicinity of houses, cultivation, 

 seaports, etc. ; whether spreading like Anacharis, Veronica Bux- 

 baumii, etc. 



The chronology of introduced plants may be said to be of two 

 kinds, historical and prehistorical. Phytogeographers define 

 these two periods as the space intervening between the Roman 

 dominion in these islands and the discovery of America, and 

 that from the discovery of the New World to our own times. 



The ancient portion is the period assigned for the introduction 

 of the Narcissi, the Ornithogalum, the Wild Tulip, the Clove 

 Pink, the Wallflower, St. Mary's Thistle, Soapwort, Yellow 

 Fumitory, etc. 



It may be inferred, from the examples of plants which have 

 been naturalized in the British Isles within the last three hun- 

 dred years, and also from such as have been well established 

 here as spontaneous productions, that it is impossible to distin- 

 guish between such species as are to be accounted aboriginal 



