78 OARYOPHYLLALES * 



3. Fagopyrum. 357. 



1. Fagopyrum fagopyrum (L.) Karst. Buckwheat. 



Fagopyrum esculentum Moencli. 

 Sometimes escapes from cultivation. 



4. Polygonum. 358. 



Stems without recurved prickles. 

 Erect or decumbent herbs, calyx lobes neither winged nor keeled in 

 fruit 

 Leaves large at least some of them over 5 cm. long. 



Racemes dense or loose flowered, flowers not 1 cm. apart. 

 Racemes terminal only, usually solitary, plants aquatic. 

 Ocrea without a foliaceous spreading tip. 



Plants usually floating, glabrous. 1, P. amphibium. 



"Plants usually emersed, glabrous. 3. P. emersum. 



Ocrea with a foliacious tip. 2. P. hartwrightii. 



Racemes axillary as well as terminal, several. 

 Ocrea without a fringe of marginal bristles. 



Racemes erect. 6. P. pennsylvanicum. 



Racemes drooping. 



Styles united only at the base. 4. P. incarnatum. 



Styles united to the middle. 5. P. lapathifolium. 



Ocrea fringed with marginal bristles. 

 Racemes dense flowered. 7. P. percicaria. 



Racemes loose flowered. 



Racemes drooping, flowers green. 10. P. hydropiper. 



Racemes erect. 



Flowers rose-colored. 8. P. periscarioides. 



Flowers green. 11. P. punctatum. 



Racemes interrupted, flowers 1 cm. apart. 13. P. virginicum. 



Leaves small, not over 5 cm. long, generally much less. 

 Fruit not reflexed. 

 Achenes 2-3 mm. long, little if at all exserted. 

 Plants decumbent. 

 Leaves mostly acute, achenes 2 mm. long. 14. P. aviculare. 

 Leaves mostly obtuse, achenes 3 mm. long. 



15. P. buxiforme. 

 Plants erect or ascending. 



Leaves oval to ovate, flower 1 or 2 in each axil. 



16. P. erectum. 

 Leaves lanceolate or linear-lanceolate. 

 Stems telete, leaves fiat. 



Leaves persistent, achenes reticulate, dull. 



18. P. ramosissimum. 

 Leaves fugacious, achene, smooth, shining. 



19. P. camporum. 



Stems 4-angled. very slender. 21. P. tenui. 



Achenes 5-6 mm. long, exserted. 20. P. exsertum. 



Fruit reflexed, perianth 4-5 mm. long. 22. P. douglassii. 



Climbing vines, outer calyx lobes keeled or winged in fruit. 



Outer calyx lobes merely keeled, achenes 3 mm. long. 



23. P. convolculus. 



