Mapping is tentative, given the recent segregation of diffusa In its broad sense, this annual species (with type from rocky sites near Knoxville) occurs widely on calcareous outcrops and roadsides in the Ozark region, Interior Low Plateaus and other calcareous regions in midwestern and southeastern states. But there is considerable variation in robustness, glandularity and sepal vein number; see also notes under diffusa and muscorum (?= M. patula var robusta). Typical patula in Ky. is generally on deeper soils than diffusa, such as rocky pastures and roasides, where disturbance appears to be needed for its persistence. For example, they are especially common along roadsides in TRIG (including the Trace in LBL) and at some other western localities. Such plants appear relatively short and short-leaved, generally with 5-veined sepals. Typical patula appears to include the glabrous f. pitcheri (Nutt.) and the glandular f. media of Steyermark (1963). With some biogeographic parallels, cryptic variants may also exist among associated xerophytic calciphiles in Sedum, Cerastium, Houstonia, Rudbeckia, Allium and Sporobolus.