Plants perennial; taproot stout; caudex much-branched, woody, producing short, decumbent, leafy sterile shoots and erect flowering shoots. Stems 15–45 cm, pubescent and glandular-viscid distally, sparsely pubescent to ± glabrous proximally. Leaves mostly in dense basal tufts; basal blades oblanceolate to elliptic, 1–3.5 cm × 3–10 mm, narrowed to base, apex acute, scabrous-puberulent to subglabrous; cauline in 2–3 pairs, distal sessile, reduced, blade linear-lanceolate to lanceolate, 1.5–4 cm × 2–6 mm. Inflorescences cymose, (1–)3–5(–7)-flowered, open, bracteate, bracteolate, pubescent and viscid with stipitate glands; cyme open, slender-branched; bracts and bracteoles narrowly lanceolate, 2–15 mm, herbaceous. Pedicels divaricate, often curved near apex and/or at base, slender, 1/2–2 times longer than calyx. Flowers: calyx prominently 10-veined, campanulate, 6–10 × 2–4 mm in flower, broadening in fruit and becoming obconic with ± constricted base, ± as broad as long, pubescent and glandular, veins parallel, with pale commissures, lobes triangular, 1–2 mm, margins broad, membranous, apex acute; corolla yellowish white, sometimes tinged with pink, clawed, claw equaling or longer than calyx, limb deeply lobed, lobes 4, linear, 4–8 mm, appendages 2, narrow, ca. 1 mm; stamens exserted, equaling petals; styles 3, filamentous, much longer than petals and stamens, exceeding 2 times calyx. Capsules obovoid, equaling calyx and often splitting it, opening by 6 recurved teeth; carpophore 2–3 mm. Seeds rusty brown, often with gray bloom, broadly reniform, 1–1.8 mm, coarsely papillate. 2n = 48.
Phenology: Flowering spring–summer.
Habitat: Woodlands and forests, often in moist situations
Elevation: 200-2800 m
Silene lemmonii has typical moth-pollinated flowers. It is closely related to S. bridgesii and appears to intergrade with it. However, the small size of S. lemmonii and the presence of a compact growth of short, leafy sterile shoots usually distinguish it from S. bridgesii.