This widespread pantropical and warm temperate weed may be native to Ky. It has been common here since the 1830s (Short et al. 1833, Riddell 1835, Gm). Variation needs more study: all material from Ky. may be var. leptostachyus Boeckl., but colls. should be checked for var. macrostachyus Boekl., which is in southeastern states (W). C. esculentus is especially successful in horticultural situations, where its tuberiferous rhizomes are peristent in fresh loose soil. The small tubers (3-11 mm wide) are edible, and plants "often have a sweet aroma when bruised or during drying" (Y). The orginally African var. esculentus (= var. sativus Boeckl. or "chufa") has been cultivated for human food, and is still much used for fish, birds and mammals. That variety is probably planted often in Ky. for wildlife but naturalization is unknown anywhere in North America (FNA 23).