Opuntiads of the USA

Opuntia orbiculata Salm-Dyck ex Pfeiff.
(tentative)

Opuntia orbiculata is poorly described in the current or recent literature. As happened so often with many large Opuntia, the plant was lumped into O. engelmannii, or O. lindheimeri, etc. The plants depicted here are distinct and different from O. engelmannii, but there is a bit of doubt about the name (see note below). Spineless forms of O. orbiculata have been called O. dillei.

A note about the tentative use of the binomial, Opuntia orbiculata (by Dave Ferguson, Editor-in-Chief)

Details may be lacking, but I have pieced together clues to help me determine that the name “Opuntia orbiculata” is properly applied to the plants on this page. First, the name (O. orbiculata) is valid, but it has a confused history. Material seen by Britton and Rose was assumed by them (and I have no reason to doubt they were correct, since they were very careful workers) to be the same material that was named by Salm-Dyck. It was supposed to be from Chile (if I recall correctly), but Britton and Rose realized that this was in error and that it had to be from North America, and likely northern Mexico. Nothing similar occurs in South America. Based on the bits of information I've been able to put together and the description of Britton and Rose, the plants shown on the web site are correct. There really aren't any other candidates that fit. The descriptions themselves are not contradictory, just the presumed origins of the plants.

This uncertainty should be pointed out with "tentative" use of the name though, until the evidence is more concrete. If this name should be thrown out, the name O. dillei was given to nearly spineless plants of the same taxon, and there is no ambiguity about this name (except for Benson's incorrect belief that it is a hybrid). I am growing the clonotype of O. dillei.

As is typical of most Opuntia species, the plants are variable, and while most pads on most plants are nearly orbicular, this is not a 100% diagnostic trait; oval and roughly obdeltoid pads are common.

This is another good example of why Opuntia is so confusing. The confusion is compounded by the fact that misidentifications are very common, even in public and scientific collections.

Opuntia orbiculata, west of Roswell, NM

Close-up of plant at left

Opuntia orbiculata near Seymour, TX, November 2005

Opuntia orbiculata near Comanche, TX , November 2005

Close-up of plant from near Comanche, TX, November 2005

Opuntia orbiculata near Seymour, TX, November 2005

Opuntia orbiculata in fruit at Rio Grande Botanic Garden, Albuquerque, NM. The plant originated from material obtained about 20 miles west of Calrsbad, NM. The specimen is spinier than typical. Copyright Dave Ferguson, 2006