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, 8 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 Portoricénsis (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 
em. long, acuminate at both ends, very obscurely punctate, the midrib broad, the lateral 
nerves prominent or conspicuous beneath : ocreae 2-4 cm. long, fringed with short bristles 
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. [Polygonum Portovicense 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 mm. 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. [Polygonum 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 em. long, thin, becoming loose, sparsely 
hispidulous or nearly glabrous, eciliate : inflorescence pubescent or glandular: racemes ob- 
long, 1.5-3.5 em. 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 Pennsylvánica (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 em. long, acuminate and somewhat unsymmetrical at the base, glabrous 
or the upper ones occasionally glandular beneath, ciliate ; petioles about 1 em. long : ocreae 
1-1.5 cm. long, rather thin, eciliate : inflorescence paniculate, glandular : racemes oblong- 
cylindric, 2-5 em. long, erect, dense: ocreolae funnelform, 3 mm. long, oblique: calyx 
po or light purple, sometimes reddish, 3-4 mm. long: stamens 8 or fewer: achenes 
enticular, flat or sometimes slightly biconcave, 3-3.5 mm. long, mostly orbicular or 
E than high, short-tipped, black, smooth and shining. [Polygonum Pennsylvani- 
In dry soil, Nova Scotia to Minnesota, Nebraska and Florida. Also in Mexico. 
6. Persicaria incarnàta (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 em. 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 mm. 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 lapathifólia ( 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- 
