124 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 
[PLATE 49. ] 
49. Polygonum Engelmanni Greene. 
Polygonum tenue var. microspermum Engelmann in A. Gray, Proc. Amer. Acad. 1863, 
75 (1863); Coulter, Man. Bot. Rocky Mt. Reg. 319, not P. microspermum Jord. 
Polygonum Engelmanni Greene, Bull. Calif. Acad. Sei. 1: 126 (1884). 
Polygonum microspermum Small, Bull. Torr. Club, 19: 366 (1892). 
Annual, very slender, glabrous, scurfy, rather wiry. Stem often diffusely branched 
at the base, the branches erect-spreading, .5-2 dm. long, nearly simple or diffusely 
branched from below, reddish, four-angled or somewhat winged, usually floriferous 
throughout; leaves varying from linear-lanceolate to linear-oblanceolate, .2-1.5 em. long, 
1-2 mm. broad, light green or glaucous beneath, acute, sessile, articulated to the ocreae, 
the uppermost reduced to bracts; ocreae funnelform, 3-4 mm. long, at length slightly 
lacerate, rather inconspicuous; inflorescence axillary, consisting of clusters with from 
two to four flowers, and extending from the base to the ends of the branches; pedicels 
reflexed and at length deflexed, 1 mm. long; calyx dark green, 2-2.5 mm. long, droop- 
ing, five-parted to near the base, the segments oblong, obtuse, with whitish borders; 
stamens varying from five to eight, included; style .4 mm. long, three-parted to near the 
base, at length somewhat exserted; achene triquetrous, 2-2.6 mm. long, ovoid or oblong, 
black, smooth and shining, sometimes slightly exceeding the calyx at maturity. 
High mountains of Colorado. 
