FLORA OF CAMBRIDGESHIRE. 21 



Witcham. Stuntney; N. — 7. "Wisbech. By the railway 

 between Whittlesey and Eastrey; N. 



2. S. arvensis Linn. Charlock. 



Rapistrum arvorum, R. C. 132. Rapum sylvestre semi- 

 nibus lucidis nigris, M. M. 79. S. arvensis, M. PL 15. 

 Relh. 272. 



Corn-fields. A. June to October. 



Common throughout the county. 



The farmers tell Mr Newbould that this plant and 

 S. alba do not like precisely the same soil. At Orwell the 

 fields on one side of a road are full of this plant, on the 

 other of S. alba, although not quite exclusively in either case. 

 Apparently the latter prefers chalky land, the former clay. 



3. S. alba Linn. White Mustard. 

 Rapistrum luteum siliqua hirsuta articulata, R. C. 133. 



S. nigra, M. PL 15. Lyons, 43. Relh. 272. 



Chalky corn-fields. A. July. 



Common in the (1) Cambridge, (2) Royston, and (3) 

 Wimpole Districts. — 4. Dry Drayton. Madingley, — 5. SwafF- 

 ham Prior ! ; H. Chippenham. — 6. Haddenham. — 7. Dod- 

 dington. — 8. Wisbech, on the silt; A P. 



Diplotaxis Cand. 



1. D. muralis Cand. 



Waste gravelly ground. A. August, September. 



1. Gravel-pits near the junction of Wort's Causeway 

 with the Wool-street, where it was first noticed in this 

 county by C. C. B. in 1846. A little below Shardelow's 

 Well near Fulbourn. A weed on waste ground at the 

 Cambridge Botanical Garden, but how introduced there is 

 not known. 



