246 
THE N AERO W- LEAVED WALL MUSTARD 
of Cornwall, writes to me : “ It is most interesting to find 
the Diplotaxis tenuifolia springing up in such quantities 
on waste heaps such as you describe. In Cornwall I have 
found it at Fowey, Par, Pentewan, Penpoll, and Devoran, 
and Penpoll is the only place where it occurs on cinder 
heaps. There it grows luxuriantly on the refuse from 
the smelting works.” Mr. Davey adds that, “ taking 
Britain as a whole, it is rather a rare plant.” 
In the Flora of Plymouth it is described as “ very rare,” 
but “ plentiful in the Cattedown quarries.” ^ In the 
Flora of the English Lake District it is mentioned as being 
found on the walls of Carlisle and Penrith Castle.^ The 
author of the Flora of West Yorkshire speaks of it being 
found at Pontefract, but considers the plant very rare.® 
It has been found at Ludlow,* in Shropshire. In Guernsey 
it is said to be “ local, but abundant where it occurs,” 
while in the Island of Alderney it is so abundant that it 
is described as a “ troublesome weed.” ® In the Flora 
Bristoliensis it is called The Wall Rocket, and is stated to 
have been found in 1854 on St. Philip’s Marsh, on a wall 
at White Ladies, and at Horfield by Mr. T. B. Flower, 
and Miss M. Atwood discovered it on the edge of the quarry 
near the Suspension Bridge, on the Somersetshire side of 
the Avon.^ In the valuable compilation of the Flora of 
the Bristol Coal Field, ^ it is stated to have been found in 
1881 on old walls and buildings in Bristol and the vicinity, 
but it is considered rare. Mr. W. B. Waterfall informs 
me that he first gathered it on some old walls near the 
works of the Avon Manure Company, on St. Philip’s 
1 See Brigg’s The Flora of Plymouth (1880). 
2 See Baker’s Flora of the English Lake District (1885). 
3 See Lee’s Flora of West Yorkshire (1887). 
^ See Ley’s Flora of Herefordshire (1889). It is not found in 
Herefordshire, but at Ludlow, in Shropshire. 
5 Flora of the Bristol Coal Field (Bristol Naturalists’ Society), 
1881. 
