''Harrisia simpsonii'', or Simpson's applecactus, is a species of cactus in the

Trichocereeae Trichocereeae is a tribe of cactus that are particular to South America. There are 25 recognized genera in this tribe. Description Arborescent to shrubby, Trichocereeae normally form unsegmented, spherical to columnar stems that are usually ribb ...

tribe. It grows in the state of Florida, in the Southeastern United States. It may be found growing on shell mounds,

mangrove swamp Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive wetlands that occur in coastal intertidal zones. Mangrove forests grow mainly at tropical and subtropical latitudes because mangroves cannot withstand fre ...

s or on high hammocks, and may be associated with buttonwood (''

Conocarpus erectus ''Conocarpus erectus'', commonly called buttonwood or button mangrove, is a mangrove shrub in the family Combretaceae. This species grows on shorelines in tropical and subtropical regions around the world. Range Locations it is known from inc ...

''). It is threatened by collecting for horticulture.

References

simpsonii Cacti of the United States Endemic flora of Florida Flora without expected TNC conservation status {{Cactus-stub