This popular garden flower often escapes, and this one was blooming in early July from a crack in the sidewalk in Allegheny West. It’s known by a large number of common names, among them Persian Jewels and Rattlebox. The latter name refers to the seed pods, which grow to balls about an inch in diameter that rattle when the seeds ripen and dry.
Gray describes the genus and the species:
NIGÉLLA [Tourn.] L. FENNEL FLOWER. Sepals 6, regular, petaloid. Petals small, ungeniculate, the blade bifid. Pistils 6, partly united into a compound ovary, so as to form a several-celled capsule. — An Old World genus, with blackish aromatic seeds, noteworthy in the family in having a somewhat compound ovary. (Name a diminutive of niger, black, from the color of the seeds.)
1. H. Damascèna L. (LOVE-IN-A-MIST.) Flower bluish, overtopped by a finely divided leafy involucre.—Sometimes cultivated, and occasionally spontaneous around gardens. (Introd. from Eurasia.)