112 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 
[Pate 43. ] 
43. Polygonum exsertum Small. 
Polygonum exsertum Small, Bull. Torr. Club, 21: 172 (1894). 
Annual or perennial by creeping rootstocks, slender, glabrous, sometimes glaucescent, 
of a light or dark brownish color. Stem erect, ascending or sometimes spreading, 4-9 
dm. long, flexuous, rather conspicuously ridged, branched above or throughout, the 
branches slender and quite strict; leaves narrowly lanceolate or linear-lanceolate, or the 
lower sometimes obovate, 1-6 cm. long, .2—.7 em. broad, acute or cuspidate, nearly sessile, 
acuminate at the base; ocreae funnelform, several-parted and silvery when young, soon 
becoming much lacerate and brownish especially at the base; inflorescence axillary, con- 
sisting of clusters of from two to four flowers; pedicels angled, 5-3.5 mm. long; calyx 
greenish, 3-3.5 mm. long, five-parted or sometimes six-parted to near the base, the seg- 
ments narrowly oblong, obtuse, often with whitish or pink margins; stamens five or six, 
included; style less than .5 mm. long, three-parted usually to the base, exserted at ma- 
turity; achene triquetrous, 4-6 mm. long, narrowly pyramidal-ovoid, rounded at the 
base, inflated about the middle and somewhat constricted below the apex, chestnut- 
colored, smooth and shining, exceeding the calyx by one-third or two-thirds of its length 
when mature and slightly spirally twisted. 
Northwest Territory to Nebraska, Missouri and Illinois; also from Maine to New 
Jersey. 
