94 American Midland Naturalist Monograph No. 7 



5. Pedicels several times longer than the valves, deflexed, 

 nearly straight, jointed close to the base; wet ground, 

 common. June-July. Swamp Dock R. verticillatus L. 



4. Leaves wavy-margined or crisped, dark green. 



7. Only one of the valves bearing a small or rudimentaiy 

 tubercle; valves cordate, nearly or quite entire, 5-6 mm 

 broad ; pedicels with a conspicuous joint ; waste ground, 



occasional; nat. from Eur. May-July. Patience Dock 



R. patientia L. 



7. Usually all three valves bearing well-developed tubercles. 



8. Pedicels obscurely jointed; leaves 5-10 cm wide, the 

 lower ones narrowed at the base; stem 1-2 m tall; wet 

 ground, not coinmon, chiefly in the northern half of 

 the state. Aug. -Sept. Water Dock. [R. britannica 

 sensu auth., non L.] R. orbiculatus A.Gray 



8. Pedicels conspicuously jointed; leaves narrower, the 

 lower ones truncate or cordate at the base; stem 30- 

 90 cm tall ; cultivated and waste ground, or roadsides, 

 common; nat. from Eur. May-June. Curly Dock 

 R. crispus L. 



3. Valves with spinulose teeth. 



9. Valves 3-4 mm long, deltoid, reticulate, only one-tubercled; 

 pedicels jointed below the middle; lowest leaves broadly 

 ovate, cordate at the base; plants perennial; fields and 

 roadsides, common ; nat. from Eur. June-Aug. Bitter Dock 

 R. obtusifolius L. 



9. Valves 2 mm long, with slender teeth, all three valves tuber- 

 cled; pedicels jointed at base; leaves linear-lanceolate, 

 narrowed at base, undulate or crisped; plants annual; 

 sandy shores, local. July-Sept. [R. persicarioides sensu 



auth., non L.; R. jyiaritimus sensu auth., non L.] 



R. jueginus Phil. 



2. Polygonum L. 

 1. Flowers in small axillary clusters (or 1 or 2 in the upper axils) ; 

 leaves jointed at base; stipules silveiy; stems somewhat wiry, not 

 twining. 

 2. Stems and branches terete or nearly so, striate, prostrate or 

 ascending to erect. 

 3. Stems prostrate or spreading; sepals with white or pink mar- 

 gins; achenes dull, dark brown; waste ground, roadsides, 

 along streets, very common and variable in appearance; 

 nat. from Eur. June-Oct. [P. neglectum Besser; P. buxi- 



forme Small]. Common Knotweed P. aviculare L. 



3. Stems erect or ascending, branched; sepals with yellowish 

 green margins; native species. 



