Revis. N. Amer. Silene, 56, plate 7, fig. 55. 1947.
Plants perennial, cespitose; tap-root stout; caudex with many often subterranean branches, woody. Stems ascending, branched, wiry, leafy, slender, 10–20 cm, finely retrorse gray-puberulent. Leaves largest in mid-stem region; blade linear to narrowly lanceolate or oblanceolate, 1–4 cm × 1–5 mm, apex sharply acuminate, glandular-puberulent. Inflorescences with flowers usually solitary, terminal on branches. Pedicels shorter than calyx, glandular-puberulent. Flowers: calyx 10-veined, tubular, constricted around carpophore, umbilicate, 20–30 × 3–6 mm, papery, green, glandular-puberulent, lobes lanceolate, 2–4 mm, margins membranous, apex acute; corolla scarlet, clawed, claw equaling calyx, limb obconic, 2-lobed, 7–10 mm, margins entire or crenate, appendages ± lacerate, 1–1.5 mm; stamens exserted, ± equaling corolla lobes; styles 3, exserted, ± equaling corolla lobes. Capsules narrowly ellipsoid, equaling calyx, opening by 6 recurved, brittle teeth; carpophore ca. 5 mm. Seeds brown, reniform, 1.5 mm, rugose in concentric rings on sides, margins papillate. 2n = 48.
Phenology: Flowering summer–early autumn.
Habitat: Crevices in granite and quartzite cliffs
Elevation: 1300-2600 m
N.Mex., Tex., Mexico.
Of conservation concern.
Silene plankii is a close relative of S. laciniata, differing in its compact tufted growth, small and narrow leaves, and shallowly two-lobed petals. It is endemic to the Del Carmen Mountains on either side of the Rio Grande valley. Plants of S. laciniata with a habit and leaves similar to S. plankii but the deeply laciniate petals of S. laciniata occur on the cliffs of Santa Cruz Island off the coast of California.