Achuma or Trichocereus bridgesii is a fast-growing columnar cactus from the high deserts of Bolivia. Among the indigenous populations of Bolivia, it is sometimes called achuma or wachuma, although these names are also applied to related species such as Trichocereus pachanoi which are also used for their psychedelic effects.
The plant is a light green colour and usually has 4 to 8 ribs. It can grow 2–5 m tall with stems of up to 15–20 cm in diameter. Spines can range in colouration from honey-coloured to brown, and are located on the nodes in groups of up to 4. These spines can grow up to 6–7 cm in length and in fully grown plants are spaced evenly on the ribs, 2.5 to 3 cm apart.
As with related species, it seems to have long shamanic tradition of use throughout its native habitat. Chemical analysis of some variants of this species have shown it may include some of the most potent of the psychedelic Trichocereus species, although this is not conclusive nor does it apply to all strains of the species. Outside of its native habitat, it is one of the least known and used of the Trichocereus cacti for either its psychoactive or ornamental uses. This is not true in areas where it is the dominant species, for example, the La Paz area of Bolivia.