132 MR. STOEBY ON INDIGENOUS AND NATURALIZED PLANTS. 



tion to the actual number. This estimate will appear large 

 when we keep in view the somewhat unpromising aspect of the 

 locality under consideration. For if any one, unacquainted with 

 the neighbourhood, will take the trouble to inspect a large map 

 of the Newcastle coal-field, he will perceive, at a glance, how 

 much the surface of the country is intersected with roads, wagon- 

 ways, and railways ; and if there be taken into the account, the 

 ballast-heaps, and coal-heaps j the multitude of cinder-ovens, 

 collieries,* glass-works, and alkali-works, it will excite surprise, 

 that, under circumstances apparently so unfavourable to vegeta- 

 tion, the phsenogamous plants and ferns, springing up around us, 

 should equal in number, two fifths of the entire British Flora. 



* On Bell's map of the '^ Great Northern Coal-Field, in the Counties of 

 Northumberland and Durham," published in 1850, there are laid down, within 

 our area, no fewer than fifty-two Collieries and Coal-pits. 



