POLYGON ACE AE (BUCKWHEAT FAMILY) 159 



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

 linear to oblanceolate, 1-2 cm. long, sessile, flat or revolute, conspicuously 

 articulated to the funnel-form 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, slightly 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 solitary, nearly sessile: stamens 8: achene ovate, included, black and 

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



20. Polygonum Douglasii Greene, Bull. Calif. Acad. Sci. 1: 125. 1884. 

 Erect and slender, 1-4 dm. high, glabrous and somewhat glaucous, sometimes 

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

 sparingly scarious and lacerate above ; leaves linear to lanceolate, usually much 

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

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

 shining. P. tenue. From Arizona to British Columbia and eastward across 

 the continent. 



21. Polygonum montanum (Small) Greene, PI. 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 angles of stem and 

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

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

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

 nodding, its segments dark green or purplish except marginally and partly or 

 completely inclosing the achene, which is black, smooth and shining. (P. com- 

 mixtum Greene, 1. c. 14.) Colorado. 



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

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

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

 from narrowly oblanceolate to linear; sheaths somewhat lacerate: flowers in 

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

 ments scarious-margined: stamens 5-8, included: style 3-parted, at length 

 somewhat exserted; achene triangular, oblong, smooth and shining. (P. con- 

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



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

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

 bosely branched: leaves linear-oblong or linear-lanceolate, 5-25 cm. long, 

 conspicuously articulated to the lacerate sheaths: flowers clustered-axillary but 

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

 spicate-racemes by the shortening of the internodes: calyx whitish or pink, 

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

 stamens 8: style 3-parted; achene triangular, black, smooth and shining except 

 on the margins. Colorado; also in the north Pacific regions. 



24. Polygonum polygaloides Meis. in DC. Prodr. 14: 101. 1856. A slender 

 glabrous light green annual; stem erect, 1-2 dm. high, simple or corymbosely 

 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, Monog. Polyg. 138. pi. 56. 1895. Low 

 slender annuals, 3-15 cm. high, smooth or slightly scabrous at the nodes: 

 leaves linear, 1-4 dm. long; sheaths rather large, 2-parted or lacerate above the 

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

 but appearing as short densely terminal spikes, with imbricated bracts, nearly 

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



