Lythrum alatum Pursh var. breviflorum A. Gray; L. alatum var. linearifolium A. Gray; L. breviflorum (A. Gray) S. Watson; L. linearifolium (A. Gray) Small; L. parvulum Nieuwland; L. sanfordii Greene

Herbs perennial, slender, 5–10(–15) dm, whitish gray glaucous, glabrous. Stems erect, much-branched distally. Leaves mostly alternate, sometimes opposite proximally, branch leaves gradually smaller than those on main stem; sessile; blade oblong-lanceolate proximally, mostly linear or linear-oblong distally, 7–60 × 1–7 mm, base rounded. Inflorescences racemes. Flowers alternate, subsessile, pedicel stout, distylous; floral tube cylindrical, 5–7 × 1–1.5 mm; epicalyx segments equal or to 2 times length of sepals; petals bright rose purple, obovate, 4–6 × 2–4.5 mm; nectary encircling base of ovary; stamens 6. Capsules septicidal or septifragal. Seeds ca. 50, obovoid to fusiform. 2n = 20.

Flowering spring–fall. Wet or moist soil, margins of ponds, streams, in ditches, on salt flats; 100–2200 m; Ariz., Calif., Kans., Nev., N.Mex., Okla., Utah, Tex.; Mexico (Baja California, Chihuahua, Coahuila, Nuevo León).

Lythrum californicum sometimes is difficult to distinguish from L. alatum; it generally has a more open vegetative habit with narrowly linear leaves. Problematic intermediates between L. californicum and L. alatum var. alatum occur in Kansas and Oklahoma, and between L. alatum var. lanceolatum and L. californicum in Oklahoma and eastern Texas. Prior to the recent recognition of L. junceum in California, older collections were identified as L. californicum.