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..
1, 13. 1855. Not Blumc, 1825-26. Polygonum portoricense Bertero; Meisn. in DC. Prodr.
14: 121. 1856. Persicaria portoricensis Small, Fl. SE. U. S. 377. 1903.
Perennial, pore or less scurfy; stem erect, decumbent or floating, 3°-5° long or longer, branched, enlarged at the nodes, often dark brown. Leaves lanceolate or linear-lanceolate, 1 1/2' - 12' long, acuminate at both ends, obscurely punctate, short-petioled, the nerves prominent beneath; ocreae cylindric, sometimes bristly when young, naked when mature, sometimes hispid; racemes spicate, paniculate, often in pairs, 1'-5' long, dense, erect; calyx white or whitish, 5-parted to near the base; stamens 6-8, included; style 2-3-cleft, somewhat exserted; achene lenticular and strongly biconvex or 3-angled, l"-1 1/2" long, broadly oblong, or-bicular or even broader than high, black, smooth and shining, or minutely granular.
In wet soil, southern New Jersey and Missouri to Florida, Texas, the West Indies and South America. May-Nov.
Polygonum pennsylvanicum L. Sp. PI. 362. 1753-
Persicaria pennsylvanica Small, Fl. SE. U. S. 377. 1903-
Annual, glabrous below; stem erect, simple or branched, 1°-3° tall, the upper parts, the peduncles and pedicels glandular. Leaves lanceolate, acuminate at the apex, petioled, ciliate, 2-11' long, the upper sometimes glandular beneath; ocreae cylindric. thin, naked, glabrous; racemes panicled, erect, thick, oblong or cylindric, dense, 1'-2r long; calyx dark pink or rose-color, 5-parted; stamens 8 or fewer, style 2-cleft to about the middle; achene orbicular or mostly broader than high, 1 1/2" long, short-pointed, lenticular, smooth, shining.
In moist soil, Nova Scotia to Ontario, Minnesota, Florida and Texas. Ascends to 2000 ft. in Virginia. July-Sept.
169. 1894. Persicaria longistyla Small, Fl. SE. U. S. 377. 1903.
Annual or perennial, glabrous except the glandular upper branches and peduncles; stem erect, rather slender, 1°-3° tall, becoming somewhat woody below. Leaves lanceolate or ovate-lanceolate, 1'-6' long, acuminate at both ends, petioled, their margins undulate, slightly crisped, more or ciliolate; ocreae cylindric, entire, brittle, soon falling away; racemes panicled, sometimes geminate, l'-4' long, rather dense, erect; calyx lilac, spicuously exserted; stigmas black; achene broadly 5-parted to below the middle, the lobes petaloid; stamens 6-8, included; style 2-parted, slender, con-ovoid, lenticular, slightly gibbous on both sides, long-pointed, black, granular, but somewhat shining, 1 1/4" long.
In moist soil, southern Illinois, Missouri and Kansas to Louisiana and New Mexico. Aug.-Oct.