POLYGONACEAE 377 



cm. long, erect, dense : ocreolae funnelform, oblique, 2 mm. long, fringed with short 

 bristles : calyx dark rose-colored or sometimes pink, 4 mm. long : stamens 5, exserted : 

 achenes lenticular, 3 mm. long, broadly obovoid or orbicular, conspicuously biconvex, 

 black, slightly granular but shining. \_Polygonum emersum (Michx. ) Britton.] 



In wet places or lakes throughout North America from the Arctic regions to southern Mexico. 



2. Persicaria Portoricensis (Bertero) Small. Perennial, glabrous, but more or less 



scurfy throughout. Stem erect, at least from a decumbent base, 8-13 dm. long, enlarged at 



the nodes, often of a dark brown color : leaf-blades lanceolate or narrowly lanceolate, 3-25 



cm. long, acuminate at both ends, very obscurely jumctate, the midrib broad, the lateral 



nerves prominent or conspicuous beneath : ocreae 2-4 cm. long, fringed with short bi'istles 



when young, at length eciliate, sometimes hispid : racemes linear, 2-11 cm. long, erect, 



dense: ocreolae funnelform, about 3 mm. long, oblique, with a membranous rim: calyx 



white or whitish, about 3 mm. long : stamens 6 or sometimes 8 : styles somewhat exserted : 



achenes lenticular, 2.5 mm. long, very broadly oblong or nearly orbicular, sometimes 



slightly obovoid and broader than high, strongly biconvex, black, smooth and shining 



or sometimes minutely granular. l^Polygonimi Portoricense Bertero.] 



In swamps, southern Missouri to Texas and Florida. Also in the West Indies and South America, 

 except the extreme south. 



3. Persicaria longistyla Small. Annual or perennial, glabrous, except the upper 

 branches and peduncles. Stem erect, 3-6 dm. long, branched throughout : leaf- blades 

 lanceolate to narrowly lanceolate or sometimes ovate-lanceolate, 3-10 cm. long, acuminate 

 at both ends, undulate, ciliate, somewhat crisped; petioles 0.5-1.2 cm. long: ocreae 

 brittle, soon falling away : racemes cylindric, 2-8 cm. long, fully 1 cm. thick, many- 

 flowered but not dense, conspicuous : ocreolae funnelform, 2-2.5 mm. long, their margins 

 hyaline : calyx mostly lilac, 4 ram. long : sepals oblong, obtuse : stamens varying from 6-8 

 included : styles 3-3.5 mm. long, united to below the middle, slender, conspicuously ex- 

 serted : stigmas black : achenes lenticular, 2.5 mm. long, broadly ovoid, long-pointed, 

 slightly gibbous on the sides, dark brown or black, slightly granular, somewhat shining or 

 dull. [Pohigonum longistylum Small. ] 



In low grounds, southern Missouri to Louisiana and New Mexico. 



4. Persicaria Mexicana Small. Annual, slender, pale green, glabrous to the 

 upper branches. Stem erect, 4-7 dm. tall, more or less branched : leaf-blades varying 

 from linear-lanceolate to linear, 3-12 cm. long, firm, obscurely punctate, ciliate, inclined 

 to be revolute, short-petioled : ocreae 0.5-1.5 cm. long, thin, becoming loose, sparsely 

 hispidulous or nearly glabrous, eciliate : inflorescence pubescent or glandular : racemes ob- 

 long, 1.5-3.5 cm. long, erect, densely flowered : ocreolae funnelform, 3 mm. long, very 

 oblique, fringed with short bristles : calyx light rose-color, 2-3 mm. long : stamens 6-8 : 

 achenes lenticular, 3-4 mm. long, ovoid or broadly ovoid, flat, but inconspicuously gib- 

 bous on one side, thick-tipped, dark brown or nearly black, mostly granular and dull. 

 [Polygonum Mexicanum Small.] 



In low grounds, southern Louisiana to southern Texas and Mexico. 



5. Persicaria Pennsylvdnica ( L. ) Small. Annual, deep green. Stem erect, 3-9 

 dm. high, often much branched throughout : leaf -blades varying from narrowly to broadly 

 lanceolate, 4-22 cm. long, acuminate and somewhat unsymmetrical at the base, glabrous 

 or the upper ones occasionally glandular beneath, ciliate ; petioles about 1 cm. long : ocreae 

 1-1.5 cm. long, rather thin, eciliate : inflorescence paniculate, glandular : racemes oblong- 

 cylindric, 2-5 cm. long, erect, dense : ocreolae funnelform, 3 mm. long, oblique : calyx 

 pink or light purple, sometimes reddish, 3-4 mm. long : stamens 8 or fewer : achenes 

 lenticular, flat or sometimes slightly biconcave, 3-3.5 mm. long, mostly orbicular or 

 broader than high, short-tipped, black, smooth and shining. [Polygonum Pennsylvani- 

 cum L. ] 



In dry soil, Nova Scotia to Minnesota, Nebraska and Florida. Also in Mexico. 



6. Persicaria incarnata (Ell.) Small. Annual, nearly glabrous throughout, light 

 green. Stem erect, 6-10 dm. tall, almost simple or branched : leaf-blades lanceolate or 

 narrowly-lanceolate, 5-20 cm. long, acuminate at both ends, sparingly punctate and ciliate, 

 short-petioled : ocreae 1-2 cm. long, loose, brittle, eciliate, or occasionally ciliolate when 

 young: racemes linear, 3-8 cm. long, drooping, dense : ocreolae funnelform, 2 mm. long, 

 oblique, cuspidate : calyx whitish, green or rose-colored, 2-3 nmi. long : stamens 6 : 

 achenes lenticular, 2 mm. long, ovoid or broadly oblong-ovoid, flat and biconcave, dark 

 brown or black, smooth and shining. [Polygonum incarnatum Ell.] 



On river banks, southern New England to Minnesota, Florida and Texas. 



7. Persicaria lapathifolla ( L. ) S. F. Gray. Annual, deep green. Stem mostly erect, 

 3-6 dm. tall, thickened at the nodes, the peduncles and pedicels more or less glandular : leaf- 



