458 NATURALIZED PLANTS OF GREAT BRITAIN. [^JunC, 



epoch : Avith man a new and most powerful agency was intro- 

 duced, and it is to him and his commercial and agricultural ope- 

 rations that we are compelled to attribute nearly all the known 

 cases of naturalization, and this leads inevitably to the conclu- 

 sion that islands which share in the Flora of a continent received 

 their indigenous plants while still joined to it. Yet we can 

 scarcely pretend to appreciate the eflPect which may have been 

 exerted by natural causes through so great a length of time, and 

 under such different conditions of our planet^ as are proved by 

 Geology. 



What is said of many plants belonging to the other three sec- 

 tions of Spontaneous species cannot here be quoted at length. 

 It will suflSce to mention that among the Indigenous are to be 

 found the two Hellebores, Chelidonium majus, Berberis vulgaris, 

 Brasslca oleracea, Erysimum cheirunthoides, Diplotaxis teuuifolia 

 and D. muralis, all the Ribes, Vinca minor, Senecio saracenicus, 

 Foeniculum vulgare, Stachys germanica, Fritillaria Meleagris, 

 Spartina alterniflora ; and two that generally pass for colonists^ 

 Sinapis alba and Thlaspi arvense. Dr. Bromfi eld's playful re- 

 marks (Phyt. vol. iii. p. 889) having been mistaken for earnest, 

 it is thought necessary to pronounce in favom' of Tamus com- 

 munis. 



Doubts are expressed as to the nativity in Britain of Chenopo- 

 dium Bonus-Henricus, Brassica campesti^is* and Rapa, Vicia 

 sativa,* Prunus Cerasus,* Primus domestica, Buxus sempervirens, 

 and Lactuca Scariola (which is perhaps the wild form of the 

 Garden Lettuce). 



Papaver somnifermn, Camelina sativa, Lepidium Draba, Cu- 

 cubalus baccifer, Cuscuta Trifolii, and several Verbasca, rank as 

 merely " adventitious." 



The " involuntarily cultivated " include Valerianella olitoria, 

 Polygonum Convolvulus?, Anagallis cmrulea {A. arvensis being 

 native on sand-hills) , the Poppies, Fumitories, etc. Several others 



* In chapter ix. oi the ' Geogi'aphie Botanique,' treating of the origin of culti- 

 vated plants, it is stated that Brassica campestris (and its variety Rapa) is found 

 wild throughout Scandinavia, Siberia, and Riissia, from the Baltic to the Caucasus. 

 B. Naples, with much the same range, is the more southern plant of the two : pro- 

 bably neither extended originally to Great Britain. 



Vicia sativa is a native of southern Europe, Greece, etc. 



Pruniis Cerasus gi'ows wild in the forests of southern Caucasus ; in western 

 Russia it is thought orilv naturahzed. Prunns domesfica is also a native oi Asia. 



