This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", 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..
Polygala brevifolia- Nutt. Gen. 2: 89. 1818.
Resembling the preceding species, but is lower, more slender and weaker. Leaves shorter, often scattered on the branches and upper part of the stem; spikes smaller (3"-5" thick), on slender peduncles; wings ovate or ovate-lanceolate, obtuse or mucronulate.
Polygala verticillata L. Sp. Pl. 706. 1753.
Annual, glabrous, very slender, 6-12' high, usually branched, the branches often opposite. Basal leaves none; stem-leaves linear, 3"-15" long, 1/2"-2" wide; acute, entire, punctate, mucronulate, mostly verticillate in 4's or 5's, with some scattered ones on the stem or branches; spikes conic, long-peduncled, acute, 2" thick at the base, very dense, 4"-10" long; flowers greenish or purplish; pedicels about 1/2" long; wings broadly oval, distinctly clawed, shorter than the pod; crest of the corolla manifest; seed oblong, hairy, twice the length of the caruncle; bracts deciduous.
Polygala ambigua Nutt. Gen. 2: 89. 1818. Polygala verticillata var. ambigua Wood, Bot. & Flor. 80. 1870.
Resembling the preceding species, but often taller, 5'-16' high, very slender. Lower stem-leaves commonly verticillate, but the others all alternate; spikes long, loose, the lower flowers often quite distant; peduncles often several inches long; flowers rather larger; wings purple or purplish, nearly circular in outline; mature capsule hardly longer than the wings, which are appressed to it; seed hairy.
Polygala incarnata L. Sp. Pl. 701. 1753.
Annual, erect, glabrous, glaucous, very slender, 1°-2° high, simple, or sparingly branched. Basal leaves none; stem-leaves alternate, distant, linear or subulate, sessile, 1"-6" long, rarely wanting; spike terminal, dense, 1'-1 1/2' long, 2"-4" thick; pedicels 1/2" or less long; bracts minute or none; flowers pink or rose, 5"-6" long; corolla-tube very slender, 3"-4" long, 2-5 times the length of the wings, its keel prominently crested; wings cuspidate; seed hairy, the caruncle-lobes enveloping its beaked extremity.
In dry soil, southern Ontario to Wisconsin, New Jersey, Florida, Arkansas and Mexico. Procession- or rogation-flower. Summer.