POLYGONACEAE (BUCKWHEAT FAMILY) 159 



branched from the bas6, striate, or wing-angled below the sheaths: leaves from 

 linear to bblanCeolate, 1-2 cm. longj sessile, flat or reVblute, conspicuously 

 articulated to the fimnel-fdrm lacerate sheath: flowers in small axillary clusters, 

 green: stamens 6-8: stigma 3-cleft, nearly sessile; achene triangular, oblong, 

 smooth and shining. — Colorado to Dakota and west to Washington! 



19. Polygonum tenue Michx. Fl. Bor. Am. 1: 238. 1803. Stem slender, 

 angled,' erect, 1.5-4.5 dm. high, shghtly scabrous at the nodes: leaves narrowly 

 linear to lanceolate, 2.5-5 cm. long, 3-nerved, acute at each end and often 

 cuspidate, the margins somewhat scabrous and at length revolute: flowers 

 often soKtary, neatly sessile: stamens 8: afchene ovate, included, black and 

 shining. — New Mexico to Canada and east to the Atlantic States. 



20. Polygpntun Douglasii Grtene, Bull. Calif. Acad. Sci. 1: 125. 1884. 

 Erect aind 'slender, 1-4 dmJ high, glabrous and somewhat glaucous, soihetimes 

 slightly Scabrous at the nodes: sheaths with a close somewhat herbaceous base, 

 sparingly sbairipus and lacerate above; leaves linear to lanceblate, usually much 

 reduced above: flowers often soUtary and usually distant, soon reflexed, the 

 sepals margined with white or rose-color: stamens 8: achenes ovate; black and 

 shining. P. temte.^^-Fxom. Arizona to British Columbia and eastward across 

 the continent.' 



'21. Pblygoflum monfenum (Small) Greene, PL Baker. 3: 13. 1901. Low, 

 fastigiately branched from the base, 7-15 cm. high, the branches floriferous 

 from the base, but the flowers few among the proper leaves, most of them 

 forming a mere bracted spike beyond the foliage, all the angle's of' stem and 

 branches denticulate-scabeculous and other parts also more or less scabro- 

 puberulent: leaves obipng-lanceolate, very acute, often 2-3 cm. long, 1-nerved, 

 the nerve Sharply carinate beneath the leaf: fruiting perianth subsessile but 

 nodding, ife segrnents dark green or purplish except marginally and partly or 

 completely inclosing the achene, which is black, smoothand shining, (p. com- 

 mixtum Greene, 1. c. 14.)^3olorado. 



22. Polygonum Engelmanii Greene, Bull. Calif. Acad. Sci. 1: 126. 1884. 

 Slender, somewhat wiry scurfy annual; stems diffusely branched at the base, 

 spi;?adiing-assurgent, ,5-15 cm. high; the branches simple, or branched: leaves 

 from narrowly pblanceplate to hnear; sheaths somewhat lacerate: flowers in 

 axillary clusters of 2-4; the pedicels at length deflexed; calyx green, its seg- 

 ments scarious-mai'gined: stamens 5-8, included: style 3-parted, at length 

 somewhat exserted; achene tidangular, oblong, smooth and shining; ' (P. con^ 

 simile Greene, Pitt. 5: 202. 1903.) — High mountains of Colorado and Wyoming. 



23. Polygonum spergulariaefprme Meis. Small, Bull. Torr. Bot, Club 

 19: 366. 1892. Slender, wiry scvnfy annual, 1-3 dm. high, simple or corym- 

 bq^ely branplvBd: leaves linear-oblong or unear-lanceolate, 5-25 cm. long, 

 conspicuously articulated to the, lacerate ghea/ths : flowers clustered-axillary but 

 confined mostly to the ends of the branches and appearing as interrupted 

 sjicate-racemes by the shortening of the internbdes: calyx whitish or pink, 

 5-parted to near the base; the segments obtuse, each with a green nerve: 

 gtaniens 8: style 3-parted; achene triangular, black, smooth aiid shining except 

 on the margins. — Colorado; also in the > north Pacific regions. , 



24. joiygonum pplygaloides' Meis. in DC. Prodr. 14: 101. 1856. A slender 

 .^abrousilifeht green annual; stem erect, 1-2 dm. high, simple or corymbdsely 



branched, slightly flexuous and angled: leaves linear, 1-3 cm. long: flowers 

 axillary but the terminal internodes so short as to give a spicate or sub- 

 capitate inflorescence; bracts oblong, obtuse, scarious-winged and somewhat 

 imbricated: the calyx parted nearly to the base, white or pinkish: stamens 8, 

 included: achene ovoid, triangular. — Northern Wyoming and Montana, and 

 west to the Pacific States. 



25. Polygonum Watsonii Small, Mohog. , Polyg. 138,, pi. 56. 1'895. . Low 

 slender annuals, 3-15 cm. lii^, smooth or slightly scabi-ous at the nodes: 

 leaves linear, l-4dm. long; sheaths rather large, ;2-parted or lacerate abo-ve the 

 short scarious base: bracts sometiines scarious on the margin: flowers axillary 

 btit af>pearing as shortdehsely teraiinal spikes, -with imbricated bracts, neairly 

 sessile: the calyx green, the segments ovate, more or less rose-colored on the 



