This weedy variable annual (2n = 36-90) is widely scattered on damp fertile soils in southeastern states and in warm regions around the world. In Ky. there has been some confusion in appearance with C. communis (especially var. ludens). Both species have spathes with margins free to base; in virginica and erecta margins are fused at base. Also, there has been some confusion in nomenclature with C. nudiflora L. (M), which is an old synonym of Murdannia nudiflora (L.) Brenan. The native range of diffusa remains uncertain; although oftten considered to have originated in East Asia, colls. from the early 1800s in Missouri have suggested native status there (Y). The earliest records in Ky. appear to date from the 1890s (Kearney 1893, Price 1893), when the species was known as C. nudiflora (M). Without flowers, the species can also be confused with erecta (Y, FNA 22). C. diffusa lacks auricles on leaf sheaths; sheaths tend to be shorter (mostly 0.5-1 cm versus 1-3 cm); and blades tend to be smaller (mostly 2.5-8 cm long versus 4-15 cm). Its flowers are relatively small, with upper petals mostly 5-10 mm long (versus 8-16+ mm in other species of Ky.) All petals are blue; in erecta the lower petal is white (as in communis)..