Eulychnia acida is a flowering plant in the family Cactaceae that is found in Chile.

[2] The plant is an arborescent cactus, of mainly columnar formation that branches out in its growth, with a single base trunk, developing a profuse crown of up to three meters in diameter.

It reaches varying heights according to temperature zone and microclimate, of 1.5 to 6 m tall, with many branches.

It has long flexible thorns, sometimes robust.

The flowers are of medium size, with short petals coloured pink to white.