108 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 



[Plate 41.] 

 41. Polygonum Islandicum Meisner. 



Polygonum amcidare var. boreale Lange, Consp. Fl. Groenl. 105 (1880), not P. cam- 

 porara var. boreale Meisn. (1855). 



Polygonum boreale Small, Bull. Torr. Club, 21 : 479 (1894). 



Annual, stout, glabrous, herbaceous and somewhat fleshy. Stem ascending, 1-2 dm. 

 long, simple or sparingly branched; leaves obovate or oblong, 1-3 cm. long, .5-1 cm. 

 broad, obtuse, slightly papillose, somewhat acuminate at the base, midrib alone prom- 

 inent, short-petioled ; ocreae oblique, 5-7 mm. long, silvery or brownish, two-parted or 

 slightly lacerate; inflorescence axillary, the clusters two-flowered; pedicels slender, 3-4 

 mm. long; calyx light green, 4 mm. long, five-parted to below the middle, inclined to 

 be open, the segments obovate, obtuse, with white or cream-colored borders; stamens 

 six, included, filaments short and stout; style .3-4 mm. long, three-parted to the base, 

 included; achene triquetrous, 3.5 mm. long, ovoid, usually somewhat pointed at both 

 ends, granular and dull. 



Greenland and Iceland. 



