Most northerly cactus species

The most northerly growing species of cactus is the pygmy or brittle pricklypear (Opuntia fragilis) with a range extending as far north as 56.28°N, in the vicinity of the Peace River Valley in Alberta and British Columbia, Canada. This places it farther north than Moscow, Russia.

The most southerly growing cactus is more debated but is most likely to be a species of Austrocactus; for example, A. aonikenkensis first described in CactusWorld in June 2018 is endemic to the Patagonian province of Santa Cruz, Argentina, with a range extending to at least 50.86°S, and perhaps as far south as the city of Río Gallegos (51.6°S).

A close contender is Pterocactus australis, with a range at least as far south as El Calafete, Argentina, at a latitude c. 50.3°S.