This East Asian annual is a close relative of iria, found mostly in temperate regions (versus tropical). In Ky. it has been found only in BALL, but it has probably been overlooked in other regions (Mears & Libby 1995, Mears 1999, J). C. microiria appeared in New York and New England after 1980, but has not yet spread into southeastern states (FNA 23, W). The name C. amuricus Max. may be correct for this species rather than microiria (PL, W).