POLYGONACEAE 



77 



1. F. esculentum Moench. BUCKWHEAT. l-2 high, smoothish: 

 flowers whitish: achene smooth. Occasionally occurs along railroads and 

 in waste places. Julj- August. 



3. POLYGONUM L. 



Herbs prostrate, erect or twining. Leaves continuous with or jointed 

 to the stipules (ochreae). Calyx 4-5-parted. Stamens 5-9. Styles 2-3- 

 parted or cleft. Fruit a lenticular or triangular achene. Probably includes 

 several distinct genera. 



Plants not twining. 



Flowers in terminal racemes. I. Smartweed. 



Lower flowers, at least, in axillary clusters. II. Kuotweed. 



Plants twining. III. 



I. 

 Calyx 5-parted. 



Ochreae not bristle-bearing. 

 Perennials. 

 Annuals. 



Peduncles almost smooth. 

 Peduncles very glandular. 



Style-branches barely exserted. 

 Style-branches long-exserted. 

 Ochreae bristle bearing. 



Eacemes thick ; not interrupted. 

 Plant glabrous to puberuleut. 

 Plant hispid. 



Kacemes slender ; usually interrupted. 

 Ochreae strigose. 

 Ochreae smooth. 



Racemes usually drooping. 

 Racemes erect. 

 Calyx 4-parted. 



Plants prostrate. 

 Plants erect or ascending. 

 Leaves oblong or oval. 

 Leaves lanceolate to linear. 



Achene twice the length of the calyx. 

 Achene enclosed, or nearly so, by calyx. 

 1 or more high. 

 1 or less high. 



III. 



Stems not prickly. 



Calyx not wing-margined in fruit. 



Calyx strongly wing-margined in fruit. 

 Stems prickly. 



1. P. emersum (Michx.) Britton. l-3 

 ovate-lanceolate : spikes 1-2, I'-S' long : 

 Common in swampy ground. 



2. P. lapathifolium L. l-3 high, smooth : leaves lanceolate, 2 / -5 / 

 long : spikes erect, \'-& long : flowers white or pink : stamens 6. Infre- 

 quently occurs in waste places. 



1. P. emersum. 



2. P. lapathifolium. 



3. P. Pennsylvanicum. 



4. P. longistylum. 



5. P. Persicaria. 

 9. P. orientale. 



6. P. hydropiperoides. 



7. P. Hydropiper. 



8. P. punctatum. 



10. P. Virginianum. 



11. P. aviculare. 



12. P. erectum. 



13. P. cxsertum. 



14. P. ramossissimum. 



15. P. tenue. 



16. P. Convolvulus. 



17. P. scandens. 



18. P. sagittatum. 



high, usually hairy : leaves 

 flowers bright rose color. 



