4. Parietaria Linnaeus, Sp. Pl. 2: 1052. ; Gen. Pl. ed.5. 1753; Gen. Pl. ed. 5, 471, 1754.
Pellitory [Latin paries, wall, referring to habitat of original species]
Herbs , annual or perennial, sparsely to densely pubescent with hooked and straight, nonstinging hairs on all parts of plant, stinging hairs absent. Stems often branched from base, erect, ascending, or decumbent. Leaves alternate; stipules absent. Leaf blades deltate, orbiculate to narrowly elliptic, or lanceolate, margins entire; cystoliths rounded. Inflorescences axillary. Flowers bisexual, staminate, or pistillate, proximal flowers usually bisexual and staminate, distal flowers pistillate; involucral bracts linear to lanceolate, without hooked hairs; tepals 4, distinct, ascending, lacking hooked hairs; stamens 4; style persistent or not; stigma tufted, deciduous. Achenes stipitate, ovoid, acute or mucronate (style base sometimes persisting as apical or subapical mucro), loosely enclosed by tepals. x =7, 8, 10, 13.
Species 20-30 (5 in the flora): primarily in temperate and subtropical regions.
Mature achenes are necessary for certain determination.
Parietaria nummularifolia (Schwartz) Weddell was collected once in 1992 in Palm Beach County, Florida, in mesic woods bordering a creek (R.P. Wunderlin, pers. comm.). This species is occasionally cultivated, and the Florida collection probably represents an escape.