Arizonans are seeing unusual saguaro blooms, and experts aren't sure why

A normal saguaro normally blooms from the top. But across southern Arizona and parts of the Valley, people are seeing something strange: flowers blooming down the stem.

 "We are seeing an unusual phenomenon," said Michael Chamberland, assistant agent in urban horticulture for the UArizona Maricopa County Cooperative Extension.  "This spring, we're seeing the saguaro flowers which usually occur as a crown cluster at the top. They are occurring lower down on the stem as well."

Chamberland says it is unknown what is causing the flowers to bloom in unusual places. 

"This is something that may have been seen in the past, but may have been written off as a irregular behavior of an unusual saguaro because there are quirky saguaros out there," Chamberland explained.

Last year, he says that homeowners were reporting that their saguaros were dying. Right now, there is no direct correlation between dying saguaros and the unusual blooming.

"This behavior was not noticed before the saguaros died off last summer, but they could have the same root cause," Chamberland explained. "They could both be due to complications, stress and unusual drought, but there's maybe different facets of that for these behaviors."

The exact cause is unclear, but experts agree the rare display is a sign of distress.

Ben Wilder, director of the University of Arizona’s Desert Laboratory, said last year was the driest on record in Tucson and he suspects this year’s strange bloom is a response to that.

Although he can’t prove it, Wilder said what’s happening now could be fallout from a run of record heat in 2017 that damaged many of the cacti, disrupting their development.

Drought since then has only made things worse, according to Peachey.

"The last several years haven’t been good for saguaros, so they haven’t grown much," he told the Arizona Daily Star.

As a result, the plants have fewer new spine clusters — known as areoles — from which flowers typically sprout, so they are "reactivating" old, unused budding locations farther down the stem.

Peachy has been studying the same, 2-acre grove of saguaros near Colossal Cave since 1997 and said he’s never seen anything like this.

In addition to the side blooms, some saguaros on Peachey’s plot are sporting crowns of flowers that are more tightly packed than usual.

The same thing is happening at Saguaro National Park, where visitors have been asking a lot of questions lately that staff members can’t answer just yet.

Other columnar cacti like the organ pipe and the Mexican giant cardon regularly sprout flowers along the sides of their stems. Saguaros almost never do — at least until recently.

Long-time park biologist Don Swann said the park launched a multiyear study of the unusual blooming activity after some limited reports of it in 2020.

"It’s just an interesting phenomenon that people had noticed but (that) hadn’t really been studied," he said. "I don’t have data yet. We’re just sort of in the process of collecting data."

Saguaros generally produce flowers in early May and bear fruit in early summer.

Their waxy white blossoms only stay open for a single day — just long enough, if they’re lucky, to be cross-pollinated by a honey bee, bat or bird.

Peachey said the seeds with the best chance for success tend to come from fruit produced during the last week to 10 days of June, "just in time to catch that first monsoon."

If residents start to see their saguaro rotting or looking unwell, it's recommended to call an expert. The best way to take care of a saguaro is by watering it once a month to keep it hydrated.

As for the extra flowers, there's a silver lining: the blooms provide pollen and nectar for pollinators like bees.

The Associated Press contributed to this report.

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