The name Acanthocalycium glaucum will be familiar to many cactus collectors for the Argentine species with globular, glaucous stems (as the epithet implies) and bright, canary-yellow flowers. Less well known are closely related natural variants described under various names but now included in the expanded taxonomic concept of Echinopsis thionantha; therefore A. glaucum is now considered to be a synonym of Echinopsis thionantha subsp. glauca. It differs from subsp. thionantha, which has denser spination and white to yellow flowers. The third variant, subsp. ferrari, has flowers of variable color, from yellow to orange, red or magenta. This name was originally published by Walter Rausch as Acanthocalycium ferrari. The synonym A. variiflorum, the name under which our plants were acquired, was described by Backeberg and also belongs in subsp. ferrari. It is native to the northern Argentine provinces of Jujuy, Salta and Catamarca. HBG108049, plants grown from seed. $6.
Published in the Cactus and Succulent Journal, Vol. 84 (2), March - April, 2012