Perennial, evergreen herb or subshrub 8 - 15 cm tall Leaves: opposite, stalkless, crowded, short, less than 1.5 cm long, about 1.3 mm wide, very narrow, linear and needle-like, with a fringe of slender bristles along the edges. Inflorescence: terminal, finely glandular-hairy, with three to six flowers on stalks under 2 cm long. Flowers: 2 - 2.5 cm wide, purple to pink or nearly white, with a darker colored tube and center, radially symmetric, with a slender tube, and abruptly spreading lobes. Sepals: five, 6 - 9 mm long overall, but fused for at least half their length, then separating into linear lobes with very long, narrow, pointed, stiff tips. Petals: five, but fused into a 1 - 1.6 cm long tube, then separating into 1 cm long, 0.7 cm wide, inversely egg-shaped lobes, and often having an uneven edge or shallow notch (about 1 mm deep) at the tip. Stamens: five, with filaments attached at different heights along the inside of the petal tube, but never extending beyond the petal tube. Pistil: with a single, three-chambered, superior ovary; and three, short (1.5 - 3 mm long, usually shorter than stigmas or ovary), fused styles, which separate above the middle into three, linear stigmas. Fruit: a three-valved, three-chambered, egg-shaped capsule with one to three, relatively large (to 6 mm long), ellipsoid seeds per chamber. Stems: several, compact, clumped, and finely, glandular-hairy. The sterile stems are trailing, decumbent, and somewhat woody, while the flowering shoots are more erect.
Similar species: Phlox nivalis is superficially similar to both P. bifida and P. subulata, but both of those species have stamens extending beyond the petal tube, and longer styles (much longer than the stigmas or ovary), which are fused for nearly their entire length. In addition, P. subulata differs by having a smaller diameter flower (at most 2 cm wide). Though P. divaricata and P. pilosa also have short styles and stamens, P. nivalis can easily be distinguished by its low, decumbent form, and short, needle-like leaves. The remaining species of Phlox in the Chicago Region do not have notched petal tips.
Flowering: April to May
Habitat and ecology: Not native this far north, it has been found only once in a sandy field near a highway and railroad in Berrien County, Michigan.
Plant with trailing-decumbent, evergreen sterile shoots and erect, deciduous flowering shoots, 1-3 dm with 4-8 nodes below the infl, the axillary fascicles of reduced lvs conspicuous; main lvs subulate to lance-linear, 1-2 cm; cal glandular-puberulent; cor light purple, varying to white, 2-2.5 cm wide, its lobes entire or erose; style short; 2n=14. Sandy slopes and flats, often in open pine woods; s. Va. to Fla. and Ala.; Tex. Apr.-May. (P. hentzii)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.