POLYGON ACEAE 



77 



1. F. esculentum Moench. Buckwheat. 1°-2° high, smoothish: 

 flowers whitish: achene smooth.— Occasionally occurs along railroads and 

 in waste places. July -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. 

 Lower flowers, at least, in axillary clusters. 

 Plants twining. 



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. 



Racemes thick ; not interrupted. 

 Plant glabrous to puberuleut. 

 Plant hispid. 

 Racemes slender ; usually interrupted. 

 Ochreae strigose. 

 Ochreae smooth. 



Racemes usually drooping. 

 Racemes erect. 

 Calyx 4-parted. 



II. 

 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 



I. Smartweed. 

 II. Kuotweed. 

 IIL 



1. P. emersum. 



2. P. lapathifolium. 



P. Pennsylvanicum. 

 P. longistylum. 



Persicaria . 

 orientale. 



6. P. hydropiperoides. 



7. P. Hydropiper. 



8. P. punctatum. 

 10. P. Virginianum. 



P-3^ 



18. P. sagittatum. 

 l°-3° high, usually hairy : leaves 

 long : flowers bright rose color. — 



ovate- lanceolate : spikes 1 

 Common in swampy ground. 



2. P. lapathifoUum L. l°-3° high, smooth : leaves lanceolate, 2'-5^ 

 long : spikes erect, l'-2' long : flowers white or pink 

 quently occurs in waste places. 



stamens 6. — Infre- 



