This perennial weed is widespread across most temperate regions of North America, but less common in southeastern states and absent from much of the Coastal Plainj (K). The first report from Ky. was in 1914 by Gm, who noted: "This pest is one of the worst occurring in Kentucky... [but] Pasturage with hogs or sheep is said to destroy the weed." In Ky., unusually small-leaved or narrow-leaved forms are sometimes seen, especially in stressed or herbicided environments. Plants often recover from herbicides, and then occasionally produce diminutive shoots with leaves as small as 5-10 mm long. Separation of Convolvulus from Calystegia (diagnosed by having large bracteoles around the calyx, also distinct pollen and stigmas) remains controversial at the global level (Wood et al. 2015). It has been maintained in recent North American floras (e.g. Cr, Y, J; Spaulding 2013b), but FNA (in press) and W are combining the two genera. Convolvulus is generally distinguishable in North America as follows: calyx bracts small and on the pedicel at a distance below the calyx (versus concealing the calyx); corollas mostly 2-2.5 cm long (versus 3.5-5 cm). C. arvensis also has a much higher chromosome number than the Calystegia species in eastern states (2n = 48 or 50 versus 20 or 22), and it spreads with running roots rather than rhizomes (Cr). Wood et al. (2015) note that arvensis is: "A very variable species especially in indumentum, leaf shape and flower colour, of which many forms and varieties have been described."