Petrorhagia prolifera
Bull. Brit. Mus. (Nat. Hist.), Bot. 3: 161. 1964.
Plants annual. Stems erect, simple or branched, (6–)20–30(–60) cm; internodes glabrous or midstem ones slightly scabrous. Leaves: sheath 1–2 mm, ± as long as wide; blade 3-veined, linear to linear-lanceolate, 10–30 mm, margins serrate-scabrous. Inflorescences capitate; inflorescence bracts and involucel bracteoles enclosing flowers, broadly ovate, brown-scarious, apex obtuse or of outer bracts mucronate. Pedicels 0.1–1.5 mm. Flowers: sepals (7–)10–12 mm; petals pink to slightly purplish (rarely white), primary veins 1, veins not darkly colored near base of blade, apex truncate or emarginate. Seeds shield-shaped, 1.1–1.6(–1.8) mm, fine to coarsely reticulate. 2n = 30 (Europe).
Phenology: Flowering summer.
Habitat: Roadsides, ballast, fields
Elevation: 0-1100 m
Distribution
B.C., Ala., Ark., Del., Ga., Idaho, Ky., Md., Mich., Mo., N.J., N.Y., N.C., Okla., Pa., Tenn., Va., c, s Eurasia, introduced in Europe (Great Britain).
Discussion
Historical records for Petrorhagia prolifera exist also for California (1902; Congdon s.n., MIN), Ohio (last collected in 1896; Stair s.n., OS), and South Carolina (1800s; Durand s.n., NY).
Petrorhagia prolifera has been known in the northeastern United States since at least 1837, and its range has since expanded, with isolated populations occurring southwestward from New Jersey toward Arkansas and Oklahoma as well as western Michigan. Some introductions may have been as a contaminant in grass seed used for highway planting in Tennessee (B. E. Wofford et al. 1977). Literature reports of P. prolifera in Louisiana and West Virginia have not been confirmed.
Selected References
None.