Herbs, annual. Taproots stout. Stems simple or branched, terete. Leaves connate proximally into sheath, sessile; blade 1-veined or obscurely 3-veined, linear to narrowly lanceolate, apex acute. Inflorescences terminal, lax cymes or of solitary, mostly axillary flowers; bracts, when present, paired, foliaceous; involucel bracteoles absent. Pedicels erect. Flowers bisexual or rarely unisexual and pistillate; sepals connate proximally into tube, 25–62 mm; tube green, 10-veined, cylindric to ovoid, terete, commissures between sepals 1-veined, herbaceous; lobes green, 1-veined, linear-lanceolate, [shorter or] longer than tube, often equaling or longer than petals, margins green, herbaceous, apex acute; petals 5, purplish red or white, clawed, auricles absent, coronal appendages absent, blade apex obtuse, entire or briefly emarginate; nectaries near bases of filaments opposite sepals; stamens 10, 5 adnate to petals, 5 at base of gynoecium; filaments distinct; staminodes absent; styles (4–)5, clavate, 10–12 mm, with dense, stiffly ascending hairs proximally; stigmas (4–)5, subterminal, papillate (30×). Capsules ovoid, opening by (4–)5 ascending teeth; carpophore absent. Seeds ca. 30–60, black, reniform, laterally compressed, tuberculate, marginal wing absent, appendage absent; embryo peripheral, curved. x = 12.
Eurasia, introduced worldwide.
Species 2 (1 in the flora).
Agrostemma brachyloba (Fenzl) Hammer (A. gracilis Boissier), a species native to Greece and Asia Minor, has been reported as a garden waif in Boulder, Colorado, where it persisted for at least four years (W. A. Weber et al. 1979). It differs from A. githago in that its calyx lobes are shorter (rather than longer) than the calyx tube, and its petals, spotted on the limb, are longer (rather than shorter) than the calyx lobes.