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..
Biennial or perennial, slender, puberulent, loosely pilose, or nearly glabrous. Stems erect or ascending, 6'-2o' tall, simple or much-branched above, finally angled; basal leaves spatulate or broadly oblanceolate, 2-3' long, entire or nearly so; cauline leaves linear, or linear-lanceolate, 1 '-3' long, slightly toothed, acute or obtuse, short-petioled; flowers yellow, 3/4'-1 3/4' broad; racemes 1-4' long; calyx slightly pubescent, its tube 4"-6" long, its segments linear-lanceolate, longer than the tube; petals obovate, shallowly notched at the apex and eroded; capsule oblong club-shaped, 4"-7" long, the angles with papery glabrous wings, its faces ridged, narrowed into pedicels which are much shorter than the bodies; seeds irregular, 1/2" long, angled.
In dry soil, Connecticut to Tennessee and Georgia. June-Sept.
Erect or nearly so, perennial, 1 1/2°-3 1/2° high, often branched above, hirsute with spreading hairs. Leaves oblong-lanceolate or elliptic-lanceolate, 4 1/2 long or less, 5"-10' wide, the margins sinuate or entire, the apex acute, or that of the lower leaves obtuse; flowers leafy-bracted, 1 1/2-2 1/2 broad; tube of the calyx somewhat hirsute, the lobes with narrow hirsute tips; capsule clavate, sessile, about 10" long, hispid.
Low grounds, Ohio to Iowa, Missouri and Arkansas. Recorded from eastern New England. June-Aug.
Oenothera pumila L. Sp. Pl. Ed. 2, 493. 1762, Oenothera chrysantha Michx. Fl Bor. Am. 1: 225. 1803 Kneiffia pumila Spach, Hist. Veg. 4: 377. 1835.
Erect," branched or simple, finely puberulent, 8'-2° high. Leaves oblanceolate or oblong, obtuse or obtusish at the apex, narrowed at the base and often petioled, entire or very nearly so, 1'-2' long, 2"-4" wide, usually glabrous; the basal ones broader and shorter; flowers in terminal, leafy-bracted spikes, yellow, diurnal, 4"-12" broad; calyx-tube shorter than the ovary, the lobes linear-lanceolate, reflexed; petals obcordate; capsule sessile or short-stalked, glabrous, club-shaped, 3"-6" long, the body obovoid, somewhat wing-angled.
In dry soil, Newfoundland to Manitoba, south to New Jersey, Georgia and Wisconsin; apparently erroneously recorded from Kansas. Ascends to 2200 ft. in Virginia. June-Aug.