Plants of Southern California: Opuntia echinocarpa, O. ganderi, O. parryi, and O. wolfii: Pictorial Identification Guide

Pictorial Guide Showing How To Identify These Species
Final Comments


The western Sonoran Desert (w DSon) has a number of interesting endemic species, including three cholla species.

Most people have no trouble recognizing teddy-bear cholla, O. bigelovii, and pink teddy-bear cholla, the w DSon endemic O. fosbergii, which are easily distinguished by their overall form and the lack of spines on their fruit. Those teddy-bear chollas are discussed separately.

This page discusses four somewhat-similar chollas that are often confused with one another: Opuntia echinocarpa, O. ganderi, O. parryi, and O. wolfii.

Synonyms and type localities for these species are as follows:

Name used hereSynonymsType Locality
O. echinocarpaO. echinocarpa var. echinocarpa
Cylindropuntia echinocarpa
Mouth of Bill Williams River, Arizona
O. ganderiO. acanthocarpa var. ganderi
O. acanthocarpa ssp. ganderi
Cylindropuntia ganderi
Three miles below the old Vallecito Stage Station, San Diego County
O. parryiO. parryi var. parryi
O. echinocarpa var. parkeri
Cylindropuntia californica var. parkeri
San Felipe (O.p.), Campo (O.e.p.); both in San Diego County
O. wolfiiO. echinocarpa var. wolfii
Cylindropuntia wolfii
Mountain Springs Grade, sw Imperial County

Since two of these species, O. ganderi and O. wolfii are endemic to w DSon, and another, O. parryi, is endemic to w DSon plus adjacent inland areas, it seems surprising at first glance that more southern California botanists aren't familiar with how to distinguish these species.

But in actuality, there has been so much confusion over these species that there is no wonder that even excellent botanists throw up their hands when it comes to these species. There are at least three major sources of confusion:

The confusion over these taxa is shown in these two examples:

No one, especially myself, can fault any of the people, sources or examples above. Cacti are especially difficult to get right taxonomically, since botanists rarely study them or collect them, and many areas in southern California remain under-vouchered for cacti. In fact, the taxonomy of these species in the w DSon only regained some measure of clarity in 2001, when Rebman restored O. ganderi to its rightful place in the w DSon as a valid species.

I personally was quite confused about O. ganderi until I read an enlightening article by Jon Rebman, 2005, Gander's Cholla: Our Common But Barely Known Cactus, in the Anza-Borrego Desert Natural History Association's The Sand Paper, 34, Issue 2, p. 3. Jon then kindly spent with me some time clarifying the other species as well.

In early 2007, I began a project to determine the locations and properties of O. parryi and O. ganderi. This page is one of the results of this ongoing project.

This page shows where these species are found, especially in the desert portion of San Diego County, and how to tell the difference between them. For an overview of chollas in San Diego County, see Chollas.


See Locations.

Pictorial Guide Showing How To Identify These Species

All of these species have fruit which are moderately to densely spiny, in contrast to the spineless fruit of the teddy-bear cacti (O. bigelovii, O. fosbergii). You can almost always find fruit present on the plant somewhere, either at the tips of the stems or tangled amidst the spines below.

The following pictures show the densely-spiny fruit of each of these species, as well as a typical teddy-bear cacti fruit:

Spineless fruit of O. bigelovii / O. fosbergii

O. parryi
O. ganderi
O. wolfii
O. echinocarpa

As you can see from the very dried fruit above, you don't need fresh fruit to make this determination. These pictures were taken in January 2007; the fruit were at least six months old.

Don't expect to distinguish these four species based on their fruit; all you have to do is make sure there are spines on the fruit to rule out the teddy-bear chollas.

There are only two other cholla species in San Diego County that have spiny fruit. The first is O. acanthocarpa, which is rare and found only in the extreme northeast corner of the Anza-Borrego Desert State Park (Travertine Palms) where few people ever venture. The following assumes you are not in that area.

The second is the very different-looking pencil cholla, O. ramosissima. That species has stems literally only a pencil width wide, less than 1 cm (0.4 inch) in diameter.

The four species discussed on this page have stems at least 1.5 cm (0.6 inches) in width, two pencil widths, and usually much wider.

The following pictures shows typical stems of the four species near the stem tips:

O. parryi
O. ganderi
O. wolfii
O. echinocarpa

Note how easily O. parryi stands out. When you look at it, you see mostly the green of the stems largely unobscured by the spines. (The above picture is very typical of O. parryi but there are two populations of O. parryi with spinier stems: along the Santa Clara River in Los Angeles County, and some plants near Scissors Crossing along S2 in San Diego County. But even there the green of the stems is still quite noticeable.)

There is no need to even get close to the plants to see the difference in color. The following pictures show the appearance of the plants in the field in a distant view:

O. parryi
O. ganderi
O. wolfii
O. echinocarpa

In a view of the entire plant, for O. parryi you mostly seen the green of the stems, and the very noticeable tubercles (the elongated bumps along the stems). In contrast, for the other three species, it is the spines the draw your attention first, at least on the newest growth. Spines tend to become less prominent on older growth as age takes its toll on them. So don't be fooled if you see a lot of green on the other species below the upper portions of the branches.

All it takes to discriminate the remaining three species is attention to the branching habit of the plants.

O. ganderi has the vast majority of its new growth stems "reaching for the sky". Even if the lower stems of the plant become a bit tilted, as in the picture above, it sends out its new growth dead erect. This new growth is said to be strict, meaning that every branch is strictly parallel to each other. See two pictures by Wayne Armstrong of a field of O. ganderi that nicely illustrates this habit.

The following three pictures show some of the variability in the appearance in the field:

Note that not every stem is strict, and new growth often starts out at an ascending angle before turning to "reach for the sky". But if you look over the plant as a whole, you see a fair number of stem tips that are dead parallel and dead erect.

Note also the variability of the spines in the above pictures. Spines are simply too variable to reliably distinguish many cacti species.

O. wolfii is the hardest to discriminate from O. ganderi since its branches are strongly ascending and hence close to the erect branches of O. ganderi. But if you look at plants of O. wolfii, especially in a field of them, you won't see the tips of the branches "reaching for the sky" anywhere near as prominently. Nor will you see a large number of stem tips that are dead parallel and dead erect.

The following pictures show this difference in habit:

A baby O. bigelovii, with its single trunk and "branching mostly at its head habit", is on the right in the last picture above.

The difference in the branch angling is a bit subtle, but easily discernable once you've seen a number of specimens of each species.

The overall appearance of this species is also quite different from O. ganderi in a number of respects. The spines are denser, more uniform and whiter on O. ganderi, and less dense, often with 1-2 much longer spines, and more golden on O. wolfii.

If you have been successful in discriminating O. wolfii from O. ganderi, it is then a piece of cake to discriminate O. echinocarpa. O. echinocarpa has many branches that are spreading at right angles to its main stems, and often appears as a miniature tree with a single trunk.

The following pictures show how different O. echinocarpa looks for its branching angle:

Note how many branches are spreading at right angles in the above pictures, and try to find any similar branching in the above pictures for the other species.

The following table summarizes the differences given above, in the same order as above, which is a good way to go through the determination for a given specimen:

SpeciesDistinguishing Characteristics
O. parryiGreen stems and tubercles very visible, spines generally not prominent
O. ganderiSpines prominent on upper stems, hiding stems and tubercles; upper stems erect and parallel, "reaching for the sky"
O. wolfiiSpines prominent on upper stems, hiding stems and tubercles; upper stems ascending but mostly not parallel and erect
O. echinocarpaSpines prominent on upper stems, hiding stems and tubercles; branches spreading, with many at right angles to main stems

See also the formal key for all cholla species in Anza-Borrego Desert State Park.

Final Comments

Go to:

Copyright © 2007 by Tom Chester
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
Comments and feedback: Tom Chester
Last update: 2 March 2007