Autor: Zuccarini

“Similar to a hedgehog (or an urchin)” referring to the typical, globose and spiny aspect of the species within this genus.
Genus of plants globose to more or less elongated with age, sometimes cereoid, often caespitose, with ribs often protruding and more or less flattened. Spines straight or curved, aciculate to sturdy, rarely hooked like a fishhook.
Flowers diurnal, self-sterile, but more usually nocturnal, mostly white, also yellow or red, pollinated by bees (Anthrenoides spp., Brachyglossula communis, Callonychium sp., Ceratina catamarcensis, C. morrensis, Diadasia sp, Diaiictus sp., Lithurgus sp., Megachile sp., Pseudagapostemon jensenii) or sphingideae (Callionimo grisescens, Erinnyis elio, E. lassauxii, E. oenotrus, Eumorpha analis, E. neuburgeri, Euryglottis aper, Hyles euphorbiarum, H. lineata, Manduca armatipes, M. bergi, M. diffissa, M. sexta, M. stuarti, M. tucumana, Sphinx maura, S. phalerata, Xylophones pluto, X. schreiteri, X. tersa), more rarely by hummingbirds. Floral tube hairy, usually very long. Fruits rather small, spherical to egg-shaped, more or less hairy. Seeds variable, pretty small, black, reticulate, striate, tuberculate or papillose. Dispersion is probably provided by ants (myrmecochory).
The genus Echinopsis grows in woodland areas or grasslands, especially in meadows with rocky islets, on stony soils, in crevices of rocks; it is also partially found on saline soils (E. klingeriana), among a bushy to shrubby vegetation, or among grasses, under a humid climate characterized by a dry season during the austral summer, from 400 m up to 2400 m in altitude, together with other cacti, sometimes settled on termite mounds (E. aldolfo-friedrichii)!
Argentina (Buenos Aires, Catamarca, Entre Rios, Formosa, Jujuy, Rio Negro, Salta, Tucuman), Bolivia (Chuquisaca, Cochabamba, La Paz, Santa Cruz, Tarija), Brazil (Mato Grosso, Mato Grosso do Sul), Paraguay (Alto Paraguay, Boqueron, Central, Concepcion, Guaira, Paraguari, Presidente Hayes, San Pedro), Uruguay (Durazno, Paysandu, Salto, Tacuarembo).

Currently 23 species to debate + 2 possible subspecies:
– Echinopsis adolfofriedrichii G. Moser 1982
– Echinopsis albispinosa* K. Schum. 1903 (= E. silvestrii)
– Echinopsis ancistrophora* Spegazzini 1905
– Echinopsis ayopayana F. Ritter & Rausch 1968
– Echinopsis boyuibensis* F.Ritter 1965
– Echinopsis bridgesii* Salm-Dyck 1850 (non Trichocereus bridgesii)
– Echinopsis bridgesii subsp. vallegrandensis* (Cardenas) Lowry 2005 (= E. huotii)
– Echinopsis bridgesii subsp. yungasensis (F.Ritter) Braun & Esteves 1995
– Echinopsis calochlora* K.Schum. 1903
– Echinopsis comarapana* Cardenas 1957
– Echinopsis coronata* Cardenas 1957
– Echinopsis eyriesii* (Turpin) Pfeif. & Otto 1839
– Echinopsis hammerschmidii Cardenas 1956
– Echinopsis klingeriana Cardenas 1965 (= E. rhodotricha ssp. chacoana)
– Echinopsis leucantha* (Gillies ex Salm-Dyck) Walpers 1843
– Echinopsis mamillosa* Gurke 1907
– Echinopsis minuana Spegazzini 1905 (= E. robinsorum)
– Echinopsis oxygona* (Link) Zucc. ex Pfeiff. & Otto 1839
– Echinopsis pamparuizii Cardenas 1970 (could well be a Lobivia)
– Echinopsis rhodotricha K.Schumann 1900
– Echinopsis rojasii Cardenas 1951
– Echinopsis semidenudata (Cardenas) W.Haage 1977
– Echinopsis subdenudata* Cardenas 1956
– Echinopsis sucrensis* Cardenas 1963
– Echinopsis tubiflora* (Pfeiff.) Zucc. ex A.Dietrich 1846

References: "TAXONOMY of the CACTACEAE" -  ISBN 978-84-617-3723-9 (Vol. 1)