Petrorhagia

Herbs, annual or perennial with woody bases. Taproots slender to stout Stems erect or ascending, simple or branched proximally, terete or angular. Leaves connate proximally into sheath, sessile; blade 1- or 3-veined, linear to narrowly oblanceolate, apex acute. Inflorescences terminal, dense capitula or lax cymes, or flowers solitary; bracts paired, brown-scarious and often enclosing inflorescence; involucel bracteoles of 1-3 pairs [or absent], similar in size and texture. Pedicels erect. Flowers bisexual, occasionally unisexual and female; sepals connate proximally into tube, 4-15 mm; tube green or reddish and white or brown-scarious, 15-veined, cylindric, terete, commissures between sepals veinless, broad, scarious; lobes green, reddish, or brown, 3-veined, oblong, shorter than tube, margins white or brown, scarious, apex rounded; petals 5, pink or purplish to white, clawed (or not in P. saxifraga), auricles absent, coronal appendages absent, blade apex entire and obtuse to 2-fid to 1/ 16 of length; nectaries at filament bases; stamens 10; filaments distinct; staminodes absent; ovary 1-locular; styles 2, filiform, 2-9 mm, glabrous proximally; stigmas 2, linear along adaxial surface of styles, papillate (30×). Capsules 4-lobed, oblong, shorter than sepals, opening by 4 slightly recurving or straight teeth; carpophore present. Seeds 8-15, blackish brown, shield- or helmet-shaped, dorsiventrally compressed, reticulate to papillate, marginal wing absent, appendage absent; embryo central, straight. x = [13-, 14-], 15.

Fls individually terminating the branches, or often clustered into head-like, conspicuously involucrate cymes terminating the branches; cal often (including our spp.) subtended by 1-3 pairs of bracts; cal-tube 5-nerved, generally with membranous, veinless commissures beneath the sinuses (unlike Dianthus); pet without auricles or appendages; stamens 10; styles 2; capsule dehiscent by 4 teeth; seeds as in Dianthus. 25, mainly Mediterranean.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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