BRITTEN : FLORA OF HIGH WYCOMBE. 



125 



Mercurialis. Linn. 

 M. perennis, L. Dog Mercury. Bab. 293. Woods and shady banks. 



Order LXXIII.—CEEATOPHYLLACE^. 

 Ceratophyllum. Linn. Hornwort. 

 C. demersum, L. Bab. 293. Ponds on JSTaphill Common ; and at the foot of 

 Cookham Down, Berks. 



Order LXXIY.— CALLITEICHACE^. 

 Callitriche. Linn. Water Starwort. 

 C. verna^ L. Bab. 294. Ponds, ditches, and streams. 



Order LXXV.— UETICACE^. 

 Parietaria. Linn. 

 P. diffusa^ Koch. Wall Pellitory. Bab. 295. Old walls ; abundant at 

 Little Marlow, nearly opposite the church. 



Urtica. Linn. J^ettle. 

 U. iirens, L. Bab. 295. Waste ground, and at the foot of walls, common. 

 U. dioica, L. Bab. 295. Woods and roadsides. 



HuMULUS. Linn. Hop. 

 H. Lwpulus, L. Bab 295. Hedges, frequent. 



Order LXXYI.— ULMACE^. 

 Ulmus. Linn. Elm. 

 U. snberosa, Ehrh. Bab. 296. Woods and hedges. 



Order LXXVII.— AMENTIFEE.^. 

 Salix. Linn. Willow. 

 [I have not yet been able to determine which of the many species of this 

 difficult genus occur with us ; but hope that a list of them may be 

 published after the investigation of another season.] 



PoPULus. Linn. Poplar. 

 P. alba, L. White Poplar. Bab. 307. In Wycombe Park, and occasionally 



in woods, but doubtfully wild. 

 P. tremula, L. Aspen. Bab. 307. In woods, not unfrequent ; Whittington 

 Park. 



P. nigra, L. Black Poplar. Bab. 307. Banks of the Thames ; Whittington 

 Park. 



