This rapidly creeping, stoloniferous plant (radiating from a taproot) is an adaptive, variable weed (Nesom 2009). O. corniculata may originate from warmer regions of the Americas (Nesom 2009; W). It was tentatively reported from Ky. early after settlement (Short et al. 1833). In 1914 Gm noted: "A common weed of no great consequence.." However, these authors were using early versions of Gray's Manual, up to Robinson & Fernald (1908), which confused "corniculata" with "stricta" (then often referring to dillenii). The first good records may date from the 1930s (Greenwell 1935, Shaklette 1937). Although now widely scattered across the state, true corniculata is largely restricted to horticultural or residential settings, especially in or near greenhouses, and there still rather few verified colls.. It appears to be most frequent on medium-acid, sandy or gravelly soils. Distinction from dillenii and stricta (or florida) can be difficult with incomplete specimens. O. corniculata differs from these species as follows (F, W; Neson 2009): stems repent, rooting at most nodes, without subterranean stolons or rhizomes (versus often rhizomatous, or erect to decumbent above ground and rarely rooting); stipules oblong ("broad, brownish or purplish" in F) with distinct flanges and free auricles (versus absent or inconspicuous at least above mid-stem and without free auricles); seeds usually all brown (versus often with white transverse ridges). Leaves are often relatively deep green to purplish, especially at margins (versus not so). Nesom (2009) stated that corniculata seeds are "uniformly brown, transverse ridges brown". However, some descriptions indicate that (as in stricta) corniculata seeds are "usually brown, or with grey or white spots or lines along the ridges" (Lovett-Doust et al. 1985). Reported 2n = 24, 36, 42, 44 and 48 (versus 18-24 in dillenii and stricta).