Pawson : Weeds. 



•9 



are not to be found wild at all, but are the children of civilisa- 

 tion and cultivation only, like the common mouse, and the 

 house-sparrow and the cheese-mite. 



So far back, in some cases, is their origfin, that their parentag-e 

 can hardly be guessed. Groundsel, for example, is never to be 

 found wild, and there is no wild plant from which it seems likely 

 to have sprung. Its place of origin would appear to have 

 been North Central Europe, for here it is most abundant and 

 thriving-. I have seen it in Sicily, but it is not happy so far south. 

 Its two nearest yq.\3.X\yqs Sejieci'o sylvaticiis and S. viscosus, but 

 these are comparatively tender plants, shy and delicately bred ; 

 while the groundsel itself, if it only has a bare spot, is the 

 hardiest of mortals, blooming and seeding even in winter, 

 refusing to yield to frost or to die when it is plucked from the 

 ground, pushing out adventitious roots from the sides of its 

 stem like a stone-crop, determined to flower and to fruit before 

 it gives up the ghost. The fleshy leaves which provide it with 

 this extraordinary vitality suggest a maritime origin or a very 

 arid birthplace. Perhaps it may have come to us from the sea- 

 cliffs. 



About a fourth part of our annual plants are cornfield weeds 

 —some 70 species out of 300 — and their cradle-land is almost as 

 undetermined as their parentage. ' Colonists ' is the name given 

 to them by Watson, but whence did they emigrate? Their 

 present range extends over the cool climates of the world ; 

 but we may at any rate set it down as certain that they are all 

 plants of Central Europe or Central Asia. 



Leaving weeds for a moment — there is not much fear that 

 any American plant will get a strong hold of oar ground, and 

 still less formidable are those from the Antipodes. These are 

 all introduced continually among seeds, wool, timber, and other 

 produce ; but, although our climate is well suited to many of 

 them, and though they have abundant choice of soil, since our 

 island is an epitome of the geology of the globe, they rarely 

 spread far from the canal-sides, the mill-yards, and the ballast- 

 heaps. Aliens they are and aliens they will remain. They will 

 never become colonists, for they cannot compete with the more 

 vigorous forms of life which the keener struggle for existence 

 among greater numbers has elaborated on the wider land-area 

 of Europe and Asia. The great lakes of North America, with 

 their vast freshwater surface, sent us the Anacharis, which 

 seemed likely to be troublesome, but this seems to be now 

 dying out. 



1905 Januarj- 2. 



