Echinopsis eyriesii is a species of cacti of the genus Echinopsis. It is a very popular large caespitose cactus, widely grown for the huge nocturnal flowers. It is the best known and most commonly grown globular cactus.
Echinopsis eyriesii original habitat is Southern Brazil, Uruguay, and province of Entre Ríos Province, Argentina. It grows in grassy plains or in low hills in lowland up to 1.000 metres above sea level. In favorable conditions and after a long time, this cactus may exceptionally forms large mounds up to 1,5 m tall and 2–3 m wide. It is globular, later elongated and almost cylindrical, 15–30 cm high, 12 to 15 cm thick, dark green and heavily ribbed (9 to 18). On the ribs, there are circular areoles with very short spines (10 to 18).