Harrisia (applecactus[2] and moonlight cactus[3][4]) is a genus of night blooming cacti.

After successful pollination, rounded fruits are formed, which are red to orange in color.

[5] Plants are native to Argentina, Paraguay, Brazil, Bolivia, Uruguay, the Greater Antilles, the Bahamas, and the U.S. state of Florida.

[6] Harrisia cactus is an exotic invasive in Australia in Queensland[3][7] and New South Wales,[8] in Africa, and in the U.S. state of Hawaii.

[1] As of September 2023[update], Plants of the World Online accepted the following species separated into two subgenera:[9][1]