138 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 



[Plate 56.J 

 56. Polygonum Watsoni Small. 



Polygonum imbrkatuvi Nuttall; S. Watson, Am. Nat. 7: 665 (1873), not Raf., Bot. 

 Calif. 2: 12; Porter, Bot. Wheeler Exp. 232; Porter & Coulter, Syn. Fl. Colo. 123; 

 Coulter, Man. Bot. Rocky Mt. Reg. 319; Greene, Fl. Francis. 315. 



Annual, low, slender, glabrous and smooth except a slight scurfy roughening about- 

 the nodes. Stem erect, .5-1.5 dm. long, simple or sparingly branched, four-angled; 

 leaves linear, 1-5 cm. long, acute, divergent, those near the ends of the branches reduced 

 to linear-lanceolate bracts, .4-1 cm. long, acute, crowded and imbricated, conspicuously 

 articulated to the ocreae ; ocreae funnelform, 2-4 mm. long, silvery, two-parted but early 

 lacerate ; inflorescence axillary, consisting of clusters bearing several flowers, conflned to 

 the ends of the branches, appearing as terminal racemes; pedicels about 1 mm. long; 

 calyx green, 2 mm. long, five-parted to below the middle, the segments ovate, obtusish, 

 often somewhat colored on the margins, the outer ones not longer than the inner; 

 stamens five or fewer, included; style .2-. 3 mm. long, three-parted to below the middle, 

 included; achene triquetrous, 1.5 mm. long, narrowly-ovoid, nearly black, prominently 

 granular in ridges. 



Washington to Montana south to California and Colorado. 



