Pterocactus (2011)

By Eric Driskill (May 2011)

The genus Pterocactus is in the family Cactaceae. In 1837, Ludwig Pfeiffer described Opuntia tuberosa from plant material collected near Mendoza, Argentina. Sixty years later, Karl Schumann described Pterocactus kuntzei from plant material that also came from near Mendoza.

Taylor and Iliff provided enough evidence to ascertain that both of the plants were in fact the same plant. This resulted in Pterocactus tuberosa being the type species. Pterocactus comes from the Greek “pteron,” wing, for winged cactus. This referred to the winged seed pod.

This genus, which is in the subfamily Opuntioideae, consists of nine species. You can categorize pterocacti as dwarf geophytic shrubs with tuberous roots and short-lived aerial stems that continue to be replaced with new stems.

The stems are small and globose to cylindrical, with fine spines and glochids on the areoles. When in flower, the plants look like blooms on stick stems, as the flowers are truly terminal. the blooms range from white and pink to yellow and orange and are large compared to the stems upon which they rest.

The species range is from as far south as Patagonia at 45 degrees south latitude to as far north as Salta at 24 degrees south latitude.

What more could you ask for in a species? You have dwarf cacti with tuberous roots, short stems and big flowers. O.K., so you could request no glochids, but that shouldn’t deter you from considering adding one of these gems to your collection. A large, old specimen still won’t take up too much bench space, and they really are cool plants.

P. tuberosa may be the most often seen in collections, since their stems root easily and will over time develop tuberous roots. Though most species have cylindrical stems, there are a few species with more globose stems, such as P. araucanus and P. hickenii, which resemble small, spiny balls.

Most Pterocactus species will likely be cultivated from stem cuttings when healthy. These really are attractive plants when given enough light so they grow tightly. As for any of the plants in the Opuntioideae family or subfamily, these really are tame compared to some of the other species.