Pachycereus is a genus of about 12 species of large cacti native to Mexico and just into southern Arizona, USA. They form large shrubs or small trees up to 515 m or more tall, with stout stems up to 1 meter in diameter. Pachycereus comes from the ancient Greek “pakhus” meaning “thick” and the Latin “cereus” meaning “torch”. The genus Pachycereus contains some of the largest growing cacti of all. One species is reported to reach a height of 25 meters! Although not all species are quite that large, all of them are columnar and feature tree-like growth. Stems are ribbed and may be either a blue-green or bright green colour. Like most columnar cacti, there is a considerable difference between smaller seedling plants and the larger mature plants. Often smaller plants will be heavily armed with spines which are reduced or even absent on older stems. A few exhibit a pseudocephalium – that is an area of extremely dense spines, which gives rise to the flowers. They do well in raised beds, rockeries and large pots.

Pachycereus pringlei is a columnar cactus native to the Sonoran Desert that is the tallest of all cactus species. With specimens reportedly reaching 21 meters in height with a diameter of about 60cm, this species resembles the popular Giant Saguaro, Carnegiea gigantea but has fewer ribs. It bears white flowers that are pollinated by insects, birds and bats. Birds and bats are also responsible for spreading Pachycereus pringleis seed when they eat the fruit, which is also edible to humans. This fruit was used as a staple food by natives such as the Seri people of Sonora. Native people also utilized other parts of the cactus such as the seed, which they ground into flour, and the spines, which they used to make fishing spears. Additionally, the flesh was used medicinally as a disinfectant and a pain killer as well as for healing.