In My Vicarage Garden 



eighteen months the whole was so covered with 

 vegetation that for geologists the view was closed. 



Now in all cases of railway sides covered by 

 vegetation the commencement is made by seeds 

 blown from the neighbouring fields and hedges, 

 which find soil ready for them, and being undis- 

 turbed, grow up speedily and vigorously. But there 

 are a great many which cannot be thus accounted 

 for, many which are new to these fresh localities, 

 and many which will, in time, alter the floras of 

 different neighbourhoods, and in some cases have 

 already done so. Some of these instances of 

 plants appearing in new places I will now give, 

 confining myself to the railways. 



One of the most curious instances is the case of 

 the London rocket (Sisymbrium irio). It appeared 

 abundantly in London after the Great Fire, and 

 then disappeared. The only other place in which 

 it had been constantly noted was at Berwick- 

 upon-Tweed, where it still exists on some rubbish- 

 heaps outside the town. Earth from the rubbish- 

 heaps has constantly been carted on to the 

 different fields, but the rocket never appeared in 

 them, but 



"In 1847 a large quantity of earth was taken from an 

 adjoining field, where the irio was never known to grow, 

 and used to make the embankment on which the station of 

 the North British Railway partly stands. The irio grew up 

 in front of the bank in great profusion immediately." 

 Johnston, Botany of the Eastern Border. 



It did not remain many years in that particular 



136 



