580 POLYGONACE^E POLYGONDM 



lines long, 5-parted to the middle: stamens 8 or fewer, included: style 

 2-parted to about the middle : achenes lenticular, flat, broader than high. 

 Idaho to the Eastern States. 



P. PERSICARIA L. Sp. 361. Annual: stem erect or sometimes spread- 

 ing, 8-20 inches high, simple or branched: leaves lanceolate to linear- 

 lanceolate, 1-8 inches long, acuminate at both ends, entire or sometimes 

 erose, conspicuously punctate, nearly smooth except the more or less his- 

 pid midrib and nerves, 'short-petioled or nearly sessile, generally with a 

 dark triangular or lunate spot in the middle : ocreae cylndric or funnelform, 

 6-9 lines long, conspicuously fringed with short bristles : racemes 1-5, in 

 terminal panicles, oblong or ovoid, 6-18 lines long, mostly erect, densely- 

 flowered: calyx pink to purple or greenish, 5-cleft to the middle, the seg- 

 ments obtuse: stamens generally included: style 2- or 3-parted. included: 

 achenes broadly ovoid, pointed. In waste places throughout North and 

 South America : naturalized from Europe. 



P. kydropiperoides Michx. Fl. i, 236. Perennial, often tinged with 

 red throughout : stems erect, or the base decumbent and creeping, 1-3 feet 

 high, simple or branched above, enlarged at the joints: leaves lanceolate to 

 linear-lanceolate, 2-6 inches long, glabrous or strigillose, acute at both 

 ends, ciliate, short-petioled: ocreae cylindric or funnelform, 6-12 lines long, 

 loose, fringed with long bristles: racemes almost linear, 1-3 inches long, 

 erect, more or less interrupted : calyx about a line long, flesh-color, or 

 greenish, 5-parted to below the middle, the segments oblong or obovate: 

 stamens 8, included style shortj 3-parted, at length exserted: achenes tri- 

 quetrous, ovoid or broadly oblong. In ponds and wet places, Washington 

 to California and the Atlantic States. 



P. Hydropiper L. Sp. 361. Annual: glabrous : stems erect or assur- 

 gent, 8-24 inches high, simple, or branched throughout : leaves ovate to 

 lanceolate, 1-5 inches long, acute or acuminate at both ends, ciliate, un- 

 dulate or slightly crisped, short-petioled : ocreae cylindric, 3-6 lines long, 

 becoming somewhat funnelform and oblique fringed with long bristles, 

 often bearing 1 or 2 flowers within, racemes numerous, axillary and ter- 

 minal, 1-3 inches long rather loosely flowered and much interrupted, usual- 

 ly drooping : calyx greenish to red or white, 3-5 parted, the segments 

 rather narrowly oblong: stamens 4, sometimes 6, included: style 2-3-cleft 

 to near the base: achene lenticular or triquetrous, broadly oblong to 

 orbicular. In damp places, throughout temperate North America and 

 Europe. 



SUBGENUS iv, AVICULAIUA Meisn. Monog. Polyg. 85. Annual 

 or perennial plants with the leaves all cauline, the petioles artic- 

 ulated at the junction of the ocreae ; the upper ones reduced to 

 foliaceous bracts. Ocreae niembranaceous and usually hyaline, 

 funnelform, oblique, 2-parted, at length lacerate. Inflorescence 

 consisting of axillary clusters either widely separated or crowded* 

 into a terminal raceme. Calyx 5-parted. Stamens mostly 8. 

 Style 3-parted or wanting. Achenes triquetrous. Cotyledons in- 

 cumbent. 



* Suffruticose smooth perennials with brown stems and loose scaly 

 bark. 



P. paronychia Cham. & Scblecht. Linn, iii, 51. Bright green and 

 glabrous throughout : stems prostrate or ascending, 6-18 inches long, dif- 

 fusely branched : leaves oblong to oblong-lanceolate, apparently linear or 

 linear-lanceolate on account of the strongly revolute margins, 3-5 lines 

 long, scattered along the branches and crowded in subspicate clusters at 



