124 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 



[Plate 49.] 

 49. Polygonum Engelmanni Greene. 



Polygonum teirue var. microspermum Engelmann in A. Gray, Proc. Amer. Acad. 1863, 

 75 (1863); Coulter, Man. Bot. Rocky Mt. Eeg. 319, not P. mia-ospermum Jord. 



Polygonum Engelmanni Greene, Bull. Calif. Acad. Sci. 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 cm. 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, 

 Ijlack, smooth and shining, sometimes slightly exceeding the calyx at maturity. 



High mountains of Colorado. 



