We like big cacti and we cannot lie! The saguaro cactus occupies an undeniable place of prestige among the people in this region, no doubt due to its impressive size, charming shapes, and abundant distribution within its range (not to mention its extensive reproduction in art, film, and pop culture). We totally get it. We are just as enamored by these striking plants! But the saguaro has plenty of time in the spotlight. In this post, we’re showing some love to other equally impressive large cacti of the Sonoran Desert region: the organ pipe, cardón, and senita cactus!

Organ pipe cactus – Stenocereus thurberi 

First up, the cactus that makes music. Kidding – though that would be awesome and we are here for it! The organ pipe cactus – Stenocereus thurberi, is named for the cacti’s slender columns’ resemblance to the musical instrument. While it may not produce the same reverberating tones as the famed instrument, the organ pipe cactus does produce delicious fruits, thanks to night-blooming flowers pollinated by nectar-feeding bats. These fruits are commercially harvested and sold in some Mexican markets. 

While its U.S. range is limited mostly to Organ Pipe Cactus National Monument and the adjacent Tohono O’odham Nation, this delightful cactus with prolific sky-seeking arms grows abundantly throughout Sonora, Baja California, and the Gulf islands, ranging into Sinaloa. 

Plants of the same species may look slightly (or even dramatically) different depending on their environment, whether in size, growth pattern, or appearance, and the organ pipe is a good example. This tropical cactus is arborescent (tree-like) in Mexico, where its columns branch more often than in its northern range here in the United States. 

Flowering season: April – July

Cardón – Pachycereus pringlei

Next up, let’s meet the saguaro’s southern cousin, at least in resemblance – the cardón, elephant cactus, or Mexican giant cardón – Pachycereus pringlei. If you thought saguaros were big, enter the cardón, the tallest living cactus in the world, with plants exceeding 60 feet with numerous branches emerging from a thick trunk. You can find this cactus giant throughout Baja California, coastal Sonora, and the Gulf islands. You won’t see wild cardón growing in Arizona due to its intolerance to frost.

Reproduction and sex expression in plants is a whole fascinating topic unto itself that challenges rigid notions of sex and gender in nature. The cardón cactus is an example of trioecious breeding, where individual plants express one of several variations of gender. Some have male flowers that produce pollen (staminate), some have female flowers that produce fruits and seeds and must be pollinated (pistillate), and some have flowers that produce both pollen and fruits—these are known as “perfect flowers” (bisexual.) A few even have neuter flowers, producing neither pollen nor seeds. 

This super giant boasts a unique superpower: a symbiotic relationship with bacterial and fungal colonies on its roots that allow the plant to gain nutrients directly from surrounding air and rock. Meaning, this cactus can grow directly on bare rock, no soil necessary! Fertile flowers package these bacteria friends directly into their seeds, so that new generations can continue the symbiosis. 

Flowering season: March – June

Senita – Pachycereus schotti

With the same basic shape as the organ pipe cactus, the senita or old man cactus, Pachycereus schotti, is aesthetically distinctive among the giant columnar cacti due to their dense clusters of “whiskers” adorning the top portion of mature stems. These whiskers are really just long, bristly spines through which flowers emerge during the flowering season. These flowers will be pink, nocturnal, and smelly–at least to most of us humans. 

Is pollination a public event, or a VIP party? Most plant species are pollinated by multiple types of pollinators, attracting several (or many) different species like bees, birds, and bats (and more!) to their flowers. Even if most of the pollination is accomplished by one particular species, such as the white-winged dove with the saguaro cactus, other pollinators can still get in on the fun. It’s one big pollinator party! 

The senita cactus, like the yucca shrub, prefers an exclusive guest list. The senita and yucca and their respective favored moths demonstrate pollination-related mutualism, a rare phenomenon in the plant world! The senita moth (Upiga sp.) is an obligate pollinator of the senita, relying on the cactus for reproduction. Likewise, the senita cactus relies on its moth for survival as they accomplish the majority of pollination, though it does benefit from additional daytime co-pollinators. Senita moths lay a single egg on the open flowers. The larvae then bore into the cactus’ flowers and feast on the developing fruit and seed, with pupation taking place on the cactus stem. 

Flowering season: March – September

Where to see these charismatic giants

Visit the Desert Museum to see examples of these three cactus species in our extensive botanical gardens. A day trip to the Organ Pipe National Monument is well-worth it to get a look at organ pipes growing wild in their northernmost extent. If you can’t get enough cacti, it’s time to plan a trip to Mexico, home to the greatest diversity of cacti in the world!

Written by Elena Makansi