1. Parietaria judaica Linnaeus, Fl. Palaest. 32. 1756.
Herbs , perennial from crown, 1-8dm. Stems ascending, erect, or decumbent. Leaf blades narrowly to broadly elliptic, lance-elliptic, or ovate, 1.3-9 × 0.8-4.5 cm, base attenuate, cuneate, or broadly rounded, apex abruptly acuminate to long-attenuate. Flowers: involucral bracts 1.5-2.5 mm; tepals ca. 2-3.5 mm, longer than bracts. Achenes dark brown, symmetric, 1-1.2 × 0.6-0.9 mm, apex acute, mucro absent or minute; stipe centered, on cylindric base.
Flowering all year, with peak in late winter-spring. Cracks in sidewalks, ballast heaps, waste places, frequently about ports and coastal areas; 0-200 m; introduced; Calif., Fla., La., Mich., N.J., N.Y., Pa., Tex.; Eurasia; n Africa.
Parietaria judaica , which, in North America, is most abundant in scattered localities in California, is the only long-lived perennial species of Parietaria in the flora. Because of confusion in Europe over the correct name, plants in North America have been called P . judaica , P . officinalis of authors, not Linnaeus, P . officinalis var. erecta (Mertens & Koch) Weddell, and P . officinalis var. diffusa (Mertens & Koch) Weddell. For a clarification of the nomenclature and taxonomy of this complex, see C.C. Townsend (1968).
Parietaria judaica was first reported from Louisiana as P . diffusa Mertens & Koch, another name commonly used on herbarium specimens (J.W. Thieret 1969).