This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Soc. 1: 29. 1847. Persicaria Careyi Greene, Leaflets 1: 24. 1904.
Annual, rough-glandular throughout, stem erect, 1°-3° tall, simple or sparingly branched above. Leaves oblong-lanceolate or linear-lanceolate, the uppermost nearly linear, 2'-11' long, short-petioled the midrib, ciliate, sparingly punctate; ocreae cylin-or nearly sessile, acuminate at both ends, hispid on dric, sparsely hispid, fringed with long bristles; racemes several, narrow, terminal, loosely-flowered, drooping, 1'-2 1/2' long; calyx purplish; stamens 5 or sometimes 8; style 2-par"ted to below the middle; achene lenticular, broadly ovoid or obovoid, 11 /4'-1 1/2" long, short-pointed, thick, smooth and shining.
Polygonum Persicaria L. Sp. PI. 361. 1753. Persicaria Persicaria Small, Fl. SE. U. S. 378. 1903.
Annual, glabrous or puberulent; stem erect or ascending, simple or much branched, 1/2°-2° high. Leaves lanceolate or linear-lanceolate, 1'-6' long, shorf-petioled or nearly sessile, acuminate at both ends, conspicuously punctate, usually with a dark triangular or lunar blotch near the centre, their margins entire or slightly eroded, often ciliate; ocreae cylindric, nearly glabrous, fringed with short bristles; racemes solitary or panicled, i'-2' long, ovoid or oblong, dense, erect; calyx pink or dark purple; stamens mostly 6; style 2-3-parted to below the middle; achene broadly ovate and lenticular, often gibbous or 3-angled, 1"-1 1/4" long, smooth and shining.
In waste places, throughout North America, except the extreme north. Naturalized from Europe. Often an abundant weed. Common persicary. Spotted-knotweed. Red- or pink-weed. Heartsease. Peach-wort. Willow-weed. Red-shanks. Lover's-pride. Black-heart. June-Oct.
Polygonum persicarioides H.B.K. Nov. Gen. 2: 179.
1817. Persicaria persicarioides Small, Fl. SE. U. S. 378. 1903.
Perennial, glabrous or minutely pubescent; stem erect, decumbent or creeping, simple or branched, 1°-3° long. Leaves lanceolate or linear-lanceolate, acuminate at both ends, punctate, short-petioled or subsessile, 1 1/2'-10' long; ocreae cylindric, glabrous or sparingly strigillose, fringed with short bristles: spicate racemes more or less panicled, erect, l'-3' long, narrowly oblong or linear, loosely-flowered; calyx rose-color tinged with green, 5-parted to below the middle; stamens 8 or fewer, included; style 2-3-parted to near the base; achene lenticular and biconvex, or 3-angled, more or less gibbous, 1" long, ovoid or broadly oblong, short-pointed, black, minutely granular, but shining.
Nebraska to Mexico; widely distributed in tropical America. June-Sept.