Joshua Tree Cacti

Explore Landscapes #34

How many species of Cacti are there in Joshua Tree National Park? Well there's 15 of them - and I got to see all of them in one day during a recent JTNPA field class.

Teddy-Bear Cactus (Cylindropuntia bigelovii) in the Cholla Cactus Garden (photo not taken during the field class)

A few weeks ago, I volunteered for a JTNPA Desert Institute field class, Cacti of Joshua Tree National Park. The class was led by Melanie Davis, a field biologist for UC Riverside and a fountain of knowledge for all things botanical in the deserts of Southern California. Melanie (Mel) was a great instructor - knowledgeable, friendly, helpful - and basically an all-round lovely person.

Mel walked us through how to use a botanical key to identify cacti species in JTNP (photo © Bob Grubbs)

This was going to be an all-day workshop and we’d have to travel to seven different locations in the park to see all 15 species of cacti that are present in Joshua Tree National Park.

Mel had created a simplified (and very welcome) botanical key to help us identify the various species of cacti that we were going to discover during out field class. I hadn’t ever used a botanical key before - and am not a ‘natural’ when it comes to anything botanical - so it was great to have this simple guide to follow.

The first cacti species spotted during the field class was the Silver Cholla, which also turned out to be the most prevalent and widespread species in JTNP. It was seen at all of the seven locations that we visited.

(L-R) Botanical Key to Cacti of JTNP | Silver Cholla (Cylindropuntia echinocarpa)

The botanical key is an identification process that you go through to identify (in this case) your cacti. You start at 1 and read that description and also the 1’ description, and then ask yourself the either 1 or 1’ question. Then you continue with 2 and 2’ etc. If you reach the end of one of the key paths, then you’ve identified your cacti.

Beavertail Prickly-Pear (Opuntia basilaris)

Two distinct California desert ecosystems meet in Joshua Tree National Park, providing a diverse range of fauna and flora across its 800,000 acres, including the namesake Joshua Tree. The Colorado Desert (part of the larger Sonoran Desert) occupies the south and east of the park and is characterized by Ocotillo plants and Cholla cactus. The southern edge of the Mojave Desert extends across the north and west of the park, with the largest concentration of Joshua Trees in the western half of the park.

The two desert ecosystems were clearly evident in terms of what cacti we found where. Of the 15 cacti species we found, seven were unique to a specific location, and we didn’t see them elsewhere in the park. The most species that any one location had was eight, and the fewest was three.

(L-R) Brown-Spined Prickly-Pear (Opuntia phaecantha) | Chucky Cholla (Cylindropuntia chuckwallensis)

The Chucky Cholla was the last and most difficult species to find. Three of the cacti species, Teddy Bear, Cotton Top, and Chucky Cholla, were only found in the lower Colorado Desert.

(L-R) Club Cholla (Grusonia parishii) | Cottontop Cactus (Homalocephala polycephala)

(L-R) Fishhook Cactus (Cochemiea tetrancistra) | Foxtail Cactus (Coryphantha alversonii)

The Fishhook and Foxtail proved elusive for a little while, but eventually, we found some, and in the same location. They are quite difficult to tell apart, but fortunately, the botanical key helped us out.

Mojave Mound Cactus (Echinocereus mojavensis)

We were lucky to be out on the field class during wildflower season, and many of the cacti that we spotted had amazing, colorful flower displays. Yellow, pink, red, and purple flowers made it somewhat easier to spot some of the cacti species.

(L-R) Grizzly Bear Cactus (Opuntia polyacantha var. erinaceae) | Hedgehog Cactus (Echinocereus engelmannii)

(L-R) Pancake Prickly-Pear (Opuntia chlorotica) | Pencil Cholla (Cylindropuntia ramosissima)

California Barrel Cactus (Ferocactus cylindraceus)

It was a wonderful class, and I can highly recommend it to anyone who enjoys learning more about desert botanical life. The class will be repeating in the fall season, so get yourself onto the JTNP mailing list so that you recieve the fall catalog as soon as it comes out.