This highly variable species with regional differences grows from slender rhizomes and can form mats or small to large clumps with flower stems up to 12 inches tall, and often branched. Note the 4-angled stems, usually hairless or only soft hairs (never glandular or rough), and the white flowers with 5, pointed petals so deeply divided to the base that they appear to be 10 petals.

FLOWER: May–August. Flowers from stem tips, single or in open clusters, 1/4–3/8 inches wide (5–10 mm); 5 slender, pointed petals divided to the base; 5–10 stamens, 3 styles curled at the tip. Fruit is a dark to straw-colored, oval capsule 1/8–1/4 inch long (4–6 mm).

LEAVES: Opposite, sessile (stalkless). Blades linear to narrowly lance-shaped, 3/8–1 inch long (4–26 mm), to 3/16 inch wide (4 mm), widest at base (often hard to distinguish this), with a prominent midrib; tips pointed, margins entire, surfaces shiny, smooth, sparingly hairy.

HABITAT: Moist sandy, loamy, gravelly soils of stream banks, mountain meadows, drainages, slopes, ridges, canyons; ponderosa-Douglas fir, spruce-fir-aspen forests.

ELEVATION: 7,300–11,625 feet.

RANGE: All Rocky Mountain states and westward; circumboreal.

SIMILAR SPECIES: Long-leaf Starwort, S. longifolia, also with deeply divided petals and in NM mountains, has leaves that reach 1 5/8 inches long, and are linear from base to the tip, or widest at the middle or above (often hard to distinguish this), and the stems are more diffusely branched. Tuber Starwort, Pseudostellaria jamesiana, in much the same habitat, has petals with a notch less than 1/2 the petal length.

NM COUNTIES: Mountains of NM in high-elevation, moist habitats: Catron, Cibola, Colfax, Grant, Lincoln, Los Alamos, McKinley, Mora, Otero, Rio Arriba, San Juan, San Miguel Sandoval, Santa Fe, Sierra, Socorro, Taos, Torrance.