Plants perennial, cespitose; tap-root stout; caudex with many often subterranean branches, woody. Stems ascending, branch-ed, wiry, leafy, slender, 10-20 cm, finely retrorse gray-puberulent. Leaves largest in mid-stem region; blade linear to narrowly lance-olate or oblance-olate, 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, con-stricted 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.
Flowering summer-early autumn. Crevices in granite and quartzite cliffs; of conservation concern; 1300-2600 m; N.Mex., Tex.; Mexico.
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.
Duration: Perennial
Nativity: Native
Lifeform: Forb/Herb
General: Perennial herbs, 10-20 cm tall, from a stout taproot and branching woody caudex; stems wiry and slender, ascending and branching, finely puberulent with gray retrorse (downward-curving) hairs.
Leaves: Opposite and sessile along the stem, with the largest leaves in the mid-stem region; blades linear to narrowly lanceolate or oblanceolate, 1-3 cm long and 1-5 mm wide, with a sharply long-pointed (acuminate) tip; surfaces covered with gland-tipped hairs.
Flowers: Red and showy, solitary at branch tips, on glandular-puberulent pedicels; sepals 5, fused into a tube 2-3 cm long and 3-6 mm diameter, covered in gland-tipped hairs and prominently 10-veined; petals 5, scarlet, the limb (part of the petal that emerges from the calyx) obconic, 7-10 mm long, divided into 2 lobes near the tip, the edges entire or with rounded teeth.
Fruits: Capsules narrowly ellipsoid, about the same length as the calyx, opening by 6 recurved, brittle teeth; containing many tiny brown, kidney-shaped seeds.
Ecology: Found on igneous cliffs and rocky ledges and crevices, from 4,200-8,500 ft (1280-2591 m); flowers July-September.
Distribution: Endemic to the mountains immediately adjacent to the Rio Grande Valley in New Mexico, west Texas, and the northern border of Mexico.
Notes: This striking cliff-dwelling perennial herb is only found in the central mountain chain running parallel to the Rio Grande River. Recognize it from its showy 5-petaled red flowers, with each petal split into 2 lobes near the tip; long narrow opposite leaves; and herbage covered with gland-tipped hairs (use your hand lens). Silene plankii is most closely related to the common and widespread S. laciniata. S. plankii is smaller (usually 10-15 cm tall vs. S. laciniata at 20-60 cm tall); has smaller leaves (1-3 cm long and 1-3 mm wide, compared to S. laciniata with leaves usually longer than 2.5 cm and wider than 3 mm); and has differently-shaped flower petals (each petal divided into 2 lobes in S. plankii, compared to petals that are multi-lobed or lacinate (irregularly lobed) in S. laciniata. This is a species of conservation concern, and is on the New Mexico Rare Plant List.
Ethnobotany: Unknown
Editor: AHazelton 2017
