216 BRITISH PLANTS 



or disturbed ground, or in waste places near it, and 

 seldom, if ever, anywhere else. They are all aliens, 

 although many of them are so common and widespread 

 that they are generally regarded as native. Of these 

 long-established aliens, found only in artificial habitats, 

 the following are the most familiar : 



Poppies, wild radish, corn-cockle, common vetch ( Vicia 

 sativa), shepherd's-needle, sweet cicely, chicory, milk- 

 thistle, corn-bluebottle (Centaur ea Cyanus), the Canadian 

 fleabane (Erigeron canadense), chamomile, the fumitories 

 and brassicas, most of the chenopodiums, some spurges, 

 ivy-leaved toadflax, Geranium pusillum, Veronica agrestis, 

 V. arvensis, Lycopsis arvensis, Verbena officinalis, black 

 horehound (Ballota nigra), pennycress (Thlaspi arvense), 

 white lychnis (Lychnis vespertina), Cerastium arvense, the 

 common mallow (Malva sylvestris), melilot, goutweed 

 JZgopodium Podagraria), fooPs-parsley (Mihuso, cyna- 

 pium), corn-marigold (Chrysanthemum segetum), the corn- 

 campanula (Campanula hybrida), Stachys arvensis, Urtica 

 urens, the slender fox-tail grass (Alopecurus agrestis), 

 Bromus arvensis, and even such common and universal 

 weeds as shepherd's-purse, treacle-mustard, common 

 nightshade (Solanum nigrum), charlock (Sinapis arvensis), 

 sow-thistle (Sonchus arvensis), the white and red dead- 

 nettles (Lamium album and purpureum), and possibly also 

 the common stinging-nettle (Urtica dioica). 



It is interesting to observe in how many cases the 

 specific name indicates the nature of the plant as a weed 

 of cultivation e.g., arvensis = belonging to the ploughed 

 field, agrestis = belonging to cultivated ground, sativus 

 and segetum = sown. Most, if not all, these plants came 

 in the track of cultivation from Asia as it spread gradually 

 westwards first through the Mediterranean region, and 

 then over northern Europe. Many of them have 

 naturally found their way to the New World, and even 

 to our distant colonies. 



