URTICACEJE. 91 



ORDER LXXIX. CERATOPHYLLACE^E. (HORNWORT TRIBE.) 

 CERATOPHYLLUM. (Hornwort.) 



I. C. demersum. L. (Common Hornwort.) 

 Streams and ditches. 6, 7. 



Harrow Pond, 'stagnant ponds at Roxeth and Ruislip, etc. 

 Headstone Moat. Brook by Forty Farm. (Farrar.) 



ORDER LXXX. URTICACE.E. (NETTLE TRIBE.) 



URTICA. (Nettle) 



1. U. urens. L. (Small Nettle.) 

 Waste places and cultivated ground. 6-9. 

 Frequent at Harrow. Sparingly at Pinner. 



2. U. dioica. L. (Great Stinging Nettle.) 

 Waste places. 6-9. 



Abundant everywhere. 



HUMULUS. (Hop.) 



i. H. Lupulus. L. (Common Hop.) 



Thickets and hedges. 7, 8. 



Hedges near the Cricket Ground ; at Roxeth ; at Love 

 Lane, Pinner, and at Alperton. 



PARIETARIA. (Pellitory.) 



i. P. officinalis. L. (Common Pellitory of the Wall.) 

 Old walls. 6-9. 

 Pinner Church Wall. This is the P. di/usa, Koch. 



[Cannabis sativa, L., or Common Hemp, is occasion- 

 ally found in places where it has escaped from cultivation, 

 but it is not recognized as an English plant.] 



