#it mx Interesting Jinbitat fnr 
Jiplertaris Cennifnlia/’ t^e itarroto- 
leabeir ®tall ^nstarir. 
By ALFRED C. FRYER, Ph.D., F.C.S. 
F or many years no blade of grass or humble weed 
would grow upon the unsightly waste heaps belong- 
ing to the United Alkali Company at their Netham 
Chemical Works, Bristol. However, a little plant known 
as the Diplotaxis tenuifolia, commonly called the Narrow- 
leaved wall mustard, is fast spreading over these and 
other heaps of chemical refuse. This plant is rare in some 
counties, but it flourishes in many localities in the south, 
south-west, and east of England. It grows in about a 
third of the 112 counties and vice-counties into which 
Britain has been divided for botanical purposes. Mr. 
H. C. Watson regarded it as not indigenous to this country, 
but what he termed “ a denizen ” ; however, for many 
years past it has been growing like a native plant in many 
parts. Sir William Hooker and Dr. Arnott mention St. 
David’s, Fifeshire, as a Scottish habitat for it, but add 
that it was introduced there among ballast. Miss Anne 
Pratt says that “ it is often found in England, near houses, 
and on dry banks or old walls and heaps of rubbish about 
towns, and is very plentiful in the suburbs of London.” ^ 
Mr. F. H. Davey, who is at present engaged on the flora 
^ See Flowering Plants and Ferns of Great Britain, Anne 
Pratt, vol. i. p. 153. 
245 
