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..
Herbs (shrubs or trees in tropical regions), with opposite 3-9-nerved simple leaves, and regular perfect, often showy, but rarely odorous, generally clustered flowers. Stipules none. Calyx-tube adnate to or free from the ovary, usually 4-5-lobed, the lobes imbricated. Petals as many as the lobes of the calyx, and inserted on its throat, more or less oblique, imbricated. Stamens twice as many, or equal in number to the petals, often inclined or declined, the alternate ones sometimes shorter; anthers opening by a pore in our species. Ovary 2-several-celled (often 4-celled); style terminal, simple; stigma simple or lobed; ovules 00, anatropous. Capsule included in the calyx-tube, irregularly or loculicidally dehiscent. Seeds mainly small, with no endosperm.
About 175 genera and 3000 species, widely distributed in tropical regions, most abundant in South America.
1. RH╔XIA L. Sp. Pl. 346. 1753.
Perennial herbs, often somewhat woody at the base, sometimes tuber-bearing, with mostly sessile opposite 3-5-nerved leaves, and terminal showy cymose or rarely solitary flowers. Calyx-tube urn-shaped or campanulate, constricted at the neck, its limb 4-lobed, the lobes triangular or subulate, shorter than the tube. Petals 4, obovate, oblique, rounded refuse, or aristate at the apex. Stamens 8, equal; anthers linear or oblong, incurved or inverted in the bud. Ovary free from the calyx, glabrous, 4-celled; style slender; stigma truncate. Capsule 4-celled, 4-valved. Placentae 4. central. Seeds numerous, coiled or bent, rough. [Greek, breaking, applied originally by Pliny to a different plant.]
About 14 species, natives of the eastern United States and Cuba. Type species: Rhexia virginica L.
Stem cylindric, very pubescent.
Stem square or angled, pubescent or glabrous.
Stem more or less pubescent; leaves ovate.
Leaves oblong or lance-oblong; calyx with a few hairs above.
Leaves ovate, bristly-ciliate; calyx glabrous.
Rhexia mariana L. Sp. Pl. 346. 1753.
Stem rather slender, cylindric, simple, or branched above, very hirsute-pubescent, 1°-2° high. Leaves spreading, short-petioled, oblong, or linear-oblong, mostly acute at the apex, narrowed at the base, 1'-1 1/2' long, 2"-5" wide, pubescent with scattered bristly hairs on both surfaces, 3-nerved, the margins ciliate-serrulate; flowers loosely cymose, pedicelled, pale purple, about 1' broad; pedicels and calyx-tube glandular-pubescent; petals rounded, or sometimes aristulate; anthers linear, curved, minutely spurred on the back.