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..
[Onagra Adans. Fam. PI. 2: 85. 1763.]
Annual or biennial caulescent herbs, with mostly erect stems. Leaves alternate, undulate or toothed, sessile or short-petioled; buds erect. Flowers yellow, nocturnal, in terminal bracted spikes. Calyx-tube elongated, terete, gradually enlarged at the throat; calyx-segments narrow, the tips free in the bud. Petals 4, spreading. Stamens 8, equal in length; filaments filiform; anthers linear. Ovary 4-celled; united styles filiform; stigma 4-cleft; ovules numerous, in 2 or more rows, horizontal. Capsule 4-celled, 4-angled, more or less tapering, opening loculicidally. Seeds prismatic-angled, in 2 or more rows, horizontal. [Greek, wine-scenting, the roots being once used for that purpose.]
About 15 species, composed of many races, chiefly North American. The later flowers are often much smaller than the earlier ones on the same plant. The generic name Onagra was used for these species in our first edition, but it is properly a synonym of Oenothera. Type species: Oenothera biennis L.
Flowers small; petals linear, 1"-2" broad.
Flowers large; petals 1/2' - 2' broad.
Plants and their capsules pubescent.
Upper bracts shorter than the pods, deciduous.
Upper bracts as long as or longer than the pods, persistent.
Puberulent and with long thick-based hairs.
Plants and their capsules wholly glabrous.
Oenothera biennis var. cruciata T. & G. Fl. N. A. I: 492. 1840.
Onagra cruciata Small, Bull. Torr. Club 23: 169. 1896.
Annual, glabrate or sparingly villous. Stem erect, 2°-4° tall, usually simple, reddish or purple; leaves narrowly oblong or oblanceolate (the upper ones often lanceolate), 1 1/2-4' long, acute, serrate-denticulate, the lower ones slender-petioled. the uppermost nearly sessile; flowers small, yellow; spikes 4'-12' long, leafy-bracted. calyx-tube slender, 3/4'-1' long, sparingly villous; calyx-segments linear-lanceolate, shorter than the tube; petals linear, 3"-6" long, i"-2" broad, acutish; capsules 1' - 1 1/4' long, gradually narrowed from the base, villous; seeds prismatic-angled, 1" long.
Sandy soil, Maine to New York and Massachusetts. Ascends to 2000 ft. in the Adirondacks. Aug.-Oct.