Polygonum 



POLYGONACEAE 



Polygonum 



the ocrea 6. P. japonicu m 



Ocreae without very coarse Long bristles; 



If. blades membranous 7. /'. jucundum 



gg. Infl. laxly fid. and often elongated. 



Perianth conspicuously glandular-punc- 

 tate : achenes finely reticulate or 



striate 8 . P. hydropiper 



Perianth eglandular : achenes smooth and 



shining 9. P. caespitosum 



cc. Spikes ovoid or subglobose, capitate : ocreae not tubular 

 (Sect. Cephalophilon). 

 Lf. blades narrowly lanceolate : fls. conspicuously ex- 



serted 10 . P. criopolitanum 



Lf. blades ovate to deltoid, usually punctate : fls. not 



conspicuously exserted 11 . P. nepalense 



bb. Infl. more or less openly paniculate. 



h. Stems and petioles armed with recurved prickles (Sect. 

 Echinocaulon). 

 i. Ocreae (or some of them) expanded into herbaceous 

 wings at the top. 

 Plant glabrous; lvs. peltate : perianth becoming 



fleshy and berry-like in fr 12. P. perfoliatum 



Plants more or less pubescent; lvs. not peltate : 



perianth not becoming fleshy in fr. 

 Ocreolae densely puberulent : achenes dull black : fls. 



not exserted beyond the ocreolae 13. P. senticosum 



Ocreolae fringed with conspicuous cilia : achenes 

 lemon-yellow or brown, roughened : some of the 



fls. exserted 14 . P. thunbergii 



ii. Ocreae membranous, not foliaceous or wing-tipped. 



Lf. blades oblong-cordate, often slightly sagittate, 

 4-15 cm. long and 2-8 cm. broad: fls.: few and 



scattered in open panicles 15. P. dissitiftorum 



Lf. blades linear to oblong or ovate, up to 10 cm. 

 long and 2 cm. broad : fls. generally more dense- 

 ly arranged 16. P. strigosum 



hh. Plants not armed. 



Three of the perianth segments enlarged and bearing 

 wing-like expansions in fr.: faces of the achenes 

 black, more or less roughened (Sect. Tiniaria). 

 Plants with twining stems; lf. blades ovate-cordate.. 17. P. multiflorum 

 Plants with erect stems; lf. blades ovate to orbicular. 18. P. cnspidatum 

 Perianth segments not enlarged in fr.: faces of the 

 achene brown: lf. blades triangular (Sect. Fago- 

 Pyrum) ..19. P. fagopyrum 



1. Polygonum aviculare Linn. Knotgrass BH (Pien Hsu) (G.M. 580). Prostrate or 

 ascending herb; fls. pink, V-VII, in axillary fascicles. Eurasia; locally in An., 

 Che., Hon., Hup., Ki., Ku. Roadside weed. 



la. Polygonum aviculare Linn. var. vegetum Ledeb. (G.M. 580). Erect, robust herb. 

 An., Che., Hon., Hup., Ku. 



2. Polygonum orientale Linn. Prince's Feather $0$. (Hung Ts'ao; Red Herb) (B. 

 M. 348). Erect herb, to 2 m.; fls. pink, VII-IX; fr. black, VIII-IX. Southern 



97 



