116 PRINCIPLES OF GARDENING. [CH. II. 



mously disproportioned roots. So exhausting is its 

 nature, that it absolutely seems to change the veiy 

 staple of the soil on which it is planted. I remem- 

 ber this fact, most strikingly illustrated by a bank, 

 on which a hedge of the furze was gro\Mi in the 

 county of Essex. I had, unfortunately, no analysis 

 of the soil previously to its being thus planted ; but 

 after the furze had grown upon it for some ten or 

 more years, the colour and texture of the soil was 

 completely changed ; it appeared a mere effete sand, 

 with but the smallest power of adhesion remaining. 



Heath is another infallible demonstration that the 

 surface soil is barren and siliceous ; but it is not in- 

 dicative of the subsoil being gravelly or porous. I 

 have seen it abounding where a stiff brick earth 

 was not many inches from the surface. The fine- 

 leaved heath [Erica cinerea) is the most insepa- 

 rably associated mth sterility. The cross-leaved 

 heath {Erica tetralix) will flourish in richer and 

 better stapled soil than the preceding. The Erica 

 tetralix is that which has waxen-looldng flowers, var}^- 

 ing in colour from almost pure white to the deepest 

 pink. 



Another infallible inchcation of a barren siliceous 

 soil is the heath-grass [Triodia decumbens). Gromid 

 where it is found may be boggy, and disguised by the 

 superfluity of its undrained water, but the staple will 

 invariably be found to have a large excess of silica. 



