112 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 



[Plate 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 cm. 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 pf from two to four flowers; pedicels angled, 3-3.5 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. 



