This tetraploid perennial (2n = 72) of rocky woods on base-rich soils occurs in scattered, somewhat disjunct regions from northeastern states to the upper midwest (FNA 5). In Ky. the only locality with an extensive well-documented population is in JESS at Jessamine Gorge (Campbell & Meijer 1989), there are a few records from elsewhere along the Ky. Rv. Palisades and along cliffs of the Green Rv. or Nolin Rv. The species also occurs in Tenn. within 25 miles of Ky. along cliffs of the Cumberland Rv. in Smith Co. and also along the Duck Rv. in Hickman and Maury Cos. (APSC; D. Estes, pers. comm.). C. arvense L., more strictly defined, is a northern, circumboreal species, but still with several variants and further revision is anticipated; native plants are reportedly the diploid ssp. strictum Gaudin (Morton 2004; FNA 5). Together, the whole arvense-velutinum complex is distinguished from other Cerastium species in eastern North America as follows (W): petals 10-18 mm long (versus 3-8 mm), 2-3× as long as sepals (versus 1-1.5x); leaves 2-7 cm long (versus 0.5-3 cm or up to 8 cm in nutans and brachypodum); plants perennial, typically with some shoots not flowering (versus annual with all shoots flowering, except in vulgare). See further notes on identification under nutans, brachypodum and vulgare. Variation within velutinum deserves further research: compared to Tenn. plants, Ky. plants have smaller flowers, with petals ca. 12 mm (versus 15 mm), sepals ca. 5.5 mm (versus 8 mm), peduncles elongating up to ca. 1-2 cm long (versus 4-5 cm), internode below inflorescence ca. 4-5 cm long (versus 9-11 cm); and the largest mid-stem leaves up to 3.5 cm long (versus 4-4.5 cm), widest at ca. 40% from base (versus 20%), [With some biogeographic parallels, cryptic variants may also exist among associated xerophytic calciphiles in Sedum, Mononeuria, Houstonia, Rudbeckia, Allium and Sporobolus.]