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..
Annual or biennial pubescent often branching herbs, with linear or linear-lanceolate acute or acuminate sessile leaves, and large purple, red or white erect flowers, solitary at the ends of axillary peduncles. Calyx ovoid-oblong, not inflated, narrowed at the throat, 10-ribbed, 5-lobed, the lobes linear, elongated and foliaceous. Petals 5, shorter than the calyx-lobes, their blades obovate or cuneate, emarginate, not appendaged; stamens 10. Styles 5, alternate with the calyx-lobes, opposite the petals. Capsule 1-celled. Seeds numerous, black. [Greek, a field-garland.]
Two known species, natives of Europe and Asia, the following typical.
Agrostemma Githago L. Sp. Pl. 435. 1753. Lychnis Githago Scop. Fl. Carn. Ed. 2, 1: 310. 1772.
Erect, 1°-3° high, simple or with few erect branches, densely pubescent throughout with whitish appressed hairs. Leaves linear-lanceolate, acute or long-acuminate, erect, 2-4' long, 2"-3" wide, the lowest narrowed at the base; flowers showy, 1'-3' broad; peduncles stout, 3'-8' long, erect; calyx ovoid, its lobes linear, foliaceous, 3 or 4 times the length of the tube and much exceeding the petals, deciduous in fruit; petals usually slightly emarginate, the blade obovate-cuneate.