OCTANDRIA TRIGYNIA. 91 



4. P. hydropiper, stem erect ; leaves lanceolate, wavy, without 

 spots; clusters lax, interrupted, drooping; stamens 6; styles 

 united half way up. Biting Persicaria. 



Hab. Ditches and watery places, frequent. Sept. 



* * Styles 3. 



5. P. avwulare, stem procumbent, herbaceous ; leaves elliptic- 

 lanceolate, rough-edged ; ribs of the stipulas distant ; flowers 

 axillary, 2 or 3 together, small. Commm Knot-grass. 



Hab. Cultivated fields, &c. very common. April Oct. 







6. P. convolvulus, stem twining, angular ; leaves heart-arrow- 

 shaped ; segments of the calyx bluntly keeled. Climbing Buck- 

 wheat. 



Hab. Cultivated fields common. June Sept. 



