108 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 
[Prate 41.] 
41. Polygonum Islandicum Meisner. 
Polygonum aviculare var. boreale Lange, Consp. Fl. Groenl. 105 (1880), not P. cam- 
YY \ 
porum 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 em. long, .5-1 em. 
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 .5-—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. 
