Petrorhagia saxifraga

Perennial herb with a taproot, mat-forming Stem: slender, freely branched. Leaves: opposite, fused at the base into sheath, stalkless, 0.5 - 2 cm long, to 1 mm wide, linear with a pointed tip, one-veined. Flowers: solitary at branch tips, pink or white, subtended by two scarious (dry, thin, and membranous) bracts. Stalk upright. Stamens ten. Styles two. Sepals: fused at the base into a tube (calyx). Calyx tube 3 - 6 mm long, cylindrical, five-veined. Petals: five, pink or white, short, three-veined, notched at the end. Fruit: a dehiscent capsule (opening by four teeth), shorter than sepals, oblong. Seeds eight to fifteen, blackish brown, disk-shaped, concave-convex.

Similar species: No information at this time.

Flowering: June to July

Habitat and ecology: Introduced from Europe. Often grown in rock gardens. A rare escape from cultivation. May occur as a weed in lawns or along roads.

Occurence in the Chicago region: non-native

Etymology: Petrorhagia means "to burst forth from rock." Saxifraga means "to break a rock."

Author: The Morton Arboretum

Cespitose perennial 0.5-4 dm, slender and freely branched; at least the lower internodes finely scabrous; lvs linear, 0.5-2(-3) cm, to 1(-2) mm wide, 1-veined, scabro- ciliolate toward the base; fls solitary (-3) at the branch-tips, closely subtended by 2(4) scarious bracts, these evidently shorter than the 5-veined, 3-6 mm cal; pet-blade short, pink or white, 3-veined, retuse or obcordate; seeds tuberculate; 2n=30, 60. Eurasian sp., cult. and sporadically escaped in our range, sometimes as a weed of lawns or roadsides. June-Oct. (Tunica s.)

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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