118 American Midland Naturalist Monograph No. 2 



19. Plants annual, adv. from Eur.; leaves (when 

 fresh) with a more or less evident dark blotch; 

 calyx pink; stamens 6; cult, ground, waste 

 places, roadsides, common. May-Sept. [Persi- 

 caria persicaria (L.) Small; P. mitis Gilib.; 



P. maculosa S. F. Gray} Lady's Thumb 



P. persicaria L. 



18. Leaves broadly ovate, acuminate, long-petioled; 

 stems 1-3 m. tall; garden escape, introd. from 



Asia. Aug.-Sept. Prince's Feather 



P. orientale L. 



9. Styles long, exserted, persistent, reflexed, becoming hooked in fruit; 

 calyx curved; sepals 4; stamens 4; racemes slender, rigid, greenish; 

 leaves ovate, acuminate; woods, common. July-Sept. [Torara vir- 



giniana (L.) Raf.] Virginia Knotweed P. virginianum L. 



2. Stems retrorsely bristly on the angles. 



22. Leaves sagittate; stem 4-angled; stamens 8; styles 3; achenes 3-angled; 

 wet ground, not common. July-Oct. [Tracaulon sagittatiim (L.) 

 Small] P. sagittatum L. 



22. Leaves hastate; stem ridged; stamens 6; styles 2; achenes lenticular; 

 wet ground, not common. July-Oct. [Tracaulon arifolium (L.) 

 Raf.] P. arifolium L. 



1. Stems twining, not prickly; flowers in panicled racemes; leaves ovate, cor- 

 date; outer sepals winged or keeled at maturity. 

 23. Outer sepals merely keeled at maturity. 



24. Achenes dull, minutely granular; stipules glabrous; plants annual; 

 nat. from Eur.; fields and waste places, common. May-Sept. Black 

 Bindweed P. convolvulus L. 



24. Achenes glossy, smooth; stipules with a fringe of stiff reflexed hairs 



at base; perennial; rocky soil, rare. June-Sept P. cilinode Michx. 



23. Outer sepals developing conspicuous wings; achenes glossy, not striate. 



25. Calyx 5-8 mm. long at maturity, flat-winged; achenes 2.5-3 mm. long; 



edges of woods, common. Aug.-Sept P. dumetorwn L. 



25. Calyx 10-12 mm. long when mature, undulate wing-margined; 

 achenes 3.5-5 mm. long; woods and roadsides, common. July-Oct. 

 P. scandens L. 



3. PoLYGONELLA Michx. — Jointweed 



{Conopyrum F. & M.; Dcloppnim Small) 



P. articulata (L.) Meisn. Sandy soil, local; n. 111. as far southw. as Peoria 

 and Kankakee counties. July-Oct. 



4. Fagopyrum Gaertn. — Buckwheat 



F. esculentum Moench. Fields or roadsides, occasionally escaped from 

 cult.; introd. from Eur. July-Sept. 



