POLYGONACEAE (BUCKWHEAT FAMILY) 



2 a Leaves about i in. broad; plant usually hairy; wings 



of fruit with 2-3 awl-like bristles 



GOLDEN DOCK. (R. persicarioides.) 

 b Leaves more than i in. broad ; plants not hairy 3 



3 a Leaves rounded and often unequal at base; wings of 



fruit with few spreading teeth 



BITTER DOCK. (R. obtusifblius.) 

 b Leaves rounded or narrowed at base; wings of fruit 



entire or notched 4 



4 a Leaves with very wavy margins. CURLED DOCK. (R. crispus.) 

 b Leaves not with very wavy margins 5 



5 a Basal leaves 1-2 ft. long, lanceolate; wings of fruit 



toothed GREAT WATER DOCK. (R. britdnnica.) 



b Basal leaves Vz-\ ft. long, narrowly oblong; wings 



of fruit entire SWAMP DOCK. (R. vertidlldtus.) 



3 FAGOP^RUM BUCKWHEAT. (F. fagopyrum*) 



4 POLfGONUM. 



1 a Stems with recurved prickles 2 



b Stems not with recurved prickles 3 



2 a Leaves comparatively broad with basal lobes spreading 



HALBERD-LEAVED TEAR-THUMB. (P. an folium.) 

 b Leaves comparatively narrow with basal lobes not 



spreading. .ARROW-LEAVED TEAR-THUMB. (P. sagittdtum.) 



3 a Plant growing in water, leaves floating 



WATER PERSICARH. (P. amphibium.) 

 b Plants not growing in water 4 



4 a Leaves not more than 2 or 3 times as long as broad, 



comparatively large 5 



b Leaves usually lanceolate or linear, usually more than 

 3 times as long as broad, sometimes less than % in. 

 long 9 



5 a Stems climbing or trailing; leaves somewhat heart- 



shaped 6 



b Stems not climbing or trailing; leaves ovate or rounded 7 



6 a Stems climbing; leaves with translucent dots; flowers 



in spikes . . . CLIMBING FALSE BUCKWHEAT. (P. scdndens.) 

 b Stems twining or trailing; leaves not with translucent 

 dots; flowers in axillary clusters 



BLACK BINDWEED. (P. convolvulus.) 



7 a Spikes conspicuously loosely-flowered ; wild species 



VIRGINIA KNOTWEED. (P. virginidnum.) 

 b Spikes densely-flowered ; cultivated species 8 



8 a Stem covered with fine hairs; flowers rose-colored 



ORIENTAL PRINCE'S FEATHER. (P. orientals*) 

 b Stem not hairy; flowers whitish 



BUSHY POLYGON UM. (P. sieboldi*) 



146 



