Brittle sandwort

Arenaria gregaria A. Heller, Bull. S. Calif. Acad. Sci. 2: 67. 1903; Alsinopsis gregaria (A. Heller) A. Heller; Arenaria nuttallii Pax subsp. gregaria (A. Heller) Maguire; A. nuttallii var. gregaria (A. Heller) Jepson; Minuartia nuttallii subsp. gregaria (A. Heller) McNeill

Leaves tightly appressed to slightly arcuate-spreading; blade 5-10 mm, apex acute to acuminate, navicular, with small mucro, not spine-tipped. Flowers: sepals 1- or 3-veined, lateral veins less distinct, ovate to lanceolate (herbaceous portion ovate to lanceolate), 3-6 mm, apex acute to acuminate; petals 1.1-1.6 times as long as sepals.

Flowering spring-summer. Sandy and rocky slopes and ridges, scree, barren rock, serpentine chaparral, Jeffrey pine woodlands; 600-3200 m; Calif., Oreg.

Variety gregaria is the variety likely the most closely related to M. decumbens, M. rosei, and M. stolonifera; it is the only one found in northwestern California and adjacent southwestern Oregon.