Manihot is an entirely New World genus with ca. 100 species. They range from the southern United States to South America. A few species are grown as ornamentals (none, however, mentioned in the European Garden Flora) or for their edible roots (M. esculenta Crantz). Probably none is trully hardy in western Europe, except perhaps M. grahamii. The latter has been recorded as an alien in Belgium.
Croizat L. (1942) A study of Manihot in North America. J. Arnold Arbor. 23: 216–225. [available online at: https://www.biodiversitylibrary.org/item/33599#page/230/mode/1up]
Rogers D.J. (1963) Studies of Manihot esculenta Crantz and related species. Bull. Torrey Bot. Club 90: 43–54.
Hayden W.J. (2016) Manihot. In: Flora North America Editorial Committee (eds.), Flora of North America North of Mexico. Vol 12. New York and Oxford: 192-196. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=119615]
Rogers D.J. & Appan S.G. (1973) Flora neotropica monograph no. 13. Manihot, Manihotoides (Euphorbiaceae). New York: Hafner 275 p.