0-7 



MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 



Ocreae cylindric, fringed with bristles. 



Racemes erect, not interrupted ; achenes lenticular. 

 Ocreae spreading; stem more or less hispid. 

 Ocreae not speading ; stem mostly glabrous. 

 Achene obovoid, biconvex. 

 Achene ovoid, plano-concave • leaves ciliate. 

 Achene ovoid-oblong, flat ; leaves eciliate. 

 Racemes erect, not interrupted ; achenes lenticular or triquetrous. 

 Ocreae conspicuously fringed ; achene broadly ovoid. 

 Ocreae inconspicuously fringed; achene narrowly ovoid. 

 Racemes erect, not interrupted ; achenes triquetrous. 

 Stem mostly glabrous ; leaves more or less petioled. 

 Ocreolae conspicuously fringed. 

 Ocreolae inconspicuously fringed. 



Leaves mostly glabrous above ; achene pointed at the 



apex. 

 Leaves mostly strigose above ; achene pointed at both 

 ends. 

 Stem more or less densely hispid with reddish hairs ; leaves ses- 

 sile or nearly so. 

 Racemes drooping, not interrupted ; achenes lenticular. 

 Racemes drooping, interrupted ; achenes lenticular or triquetrous. 

 Leaves ovate or ovate-lanceolate ; achene granular and dull. 

 Leaves lanceolate or linear-lanceolate ; achene smooth and 

 shining. 

 Racemes erect, interrupted ; achenes lenticular or triquetrous. 



2Y. P. HYDROPIPEROIDES. 



4. SUBGENUS AMBLYGONON. 



Herbaceous or suffrutescent plants, stout, annual or perennial (with the general 

 characters of subgenus Persicaria). Stem mostly erect, terete, becoming woody below, 

 branched aljoA'o. Leaves large, pubescent or glabrous, entire, petioled. Ocreae cylin- 

 dric, conspicuous Ijy the spreading summit, strigose and fringed. Inflorescence terminal 

 and axillary, paniculate, the ultimate divisions ending in spicate racemes. Racemes 

 linear or oblong, rather dense, more or less drooping. Ocreolae funnelform, oblique, 

 ciliate. Pedicels articulated at the base of the calyx. Calyx colored, showy, five-cleft, 

 investing the achene by developing after flowering. Stamens mostly seven, rarely in 

 fi\'es, sixes or eights, included. Style two-cleft, included, the stigmas capitate, large, dark- 

 colored, conspicuous. Achene lenticular, biconcave, smooth and shining, the edges 

 rounded. Albumen horny. Cotyledons incumbent. 



One species. 32. P. orientale. 



