Trichocereus skottsbergii / Echinopsis skottsbergii (chiloensis)

Trichocereus skottsbergii Echinopsis chiloensis ssp. skottsbergii Ulrich Hörner (5)

Trichocereus skottsbergii Backeberg, also called Echinopsis skottsbergii, is a columnar cactus that is closely related to Trichocereus chiloensis / Echinopsis chiloensis. Under current taxonomy it is placed as a subspecies below Trichocereus chiloensis with Echinopsis skottsbergii as currently accepted name.

Trichocereus skottsbergii grows together with Trichocereus chiloensis without forming zones of hybridization. The easiest way to differentiate Tr. skottsbergii from Trichocereus chiloensis is by comparing the number of ribs. Echinopsis skottsbergii has 16-21 ribs, while Trichocereus chiloensis only has 16-18 ribs.

Curt Backeberg gives the form T. skottsbergii v. breviatus as a valid variety, but it was probably just a regional form of the same species. In the past, there were many unnecessary descriptions made that would not stand today. In my personal opinion, all the Chilean Trichocereus species are so closely related that it might not be a bad idea to consider them as one, very big and variable species. The same treatment works well with the whole group of species around T. peruvianus.

In Chile, the variability of the genus Trichocereus is just as big as the variability of Trichocereus species in Peru or Bolivia. E. skottsbergii is extremely close to Trichocereus litoralis, also known as Trichocereus chiloensis ssp. litoralis as well. It is very difficult to distinguish them and descriptions are absolutely necessary.