Palo verde and cactus

Palo verde trees create a sea of yellow near a quirky cactus in the Catalina Foothills. Time will tell if the bloom will be a lengthy one.

Palo verde trees are putting on a spectacular show this month — cloaking seemingly endless expanses of foothills and deserts with their brilliant yellow blooms.

“It sure seems like a banner year for foothills palo verde, said John Wiens of the Botany Department at the Arizona-Sonora Desert Museum.

Some might call that almost an understatement, with some longtime residents saying they can’t recall a more intense, widespread palo verde bloom.

“We have taken more than 25 years of flowering data on that species from the hills around the Desert Museum,” Wiens said. “Our records show that the flowering can begin as early as the first week in April and as late as the 2nd week in May. The length of bloom varies, too, from 4 weeks to 8 weeks.

“Out here, this year seems to be a later start, but incredibly intense and widespread,” he said. “Time will tell if it will be a lengthy bloom as well.”

Rainfall is an important factor in the palo verde bloom, Wiens said.

“Another above-average foothill palo verde bloom out here was the spring of 1997,” he said. “We received 10.70 inches of rainfall between Oct. 1, 1996, and March 30, 1997. Leading up to this year’s bloom, the Desert Museum had 9.15 inches of rainfall. That’s phenomenal, as our average total for the entire year is less than 12 inches.”

Where to find palo verde blooms?

The short answer is: almost anywhere in and around the Tucson area.

From neighborhoods in town with mature palo verde trees, to foothills of nearby mountain ranges, to outlying deserts, it’s difficult to avoid the bright yellow blooms.

A downside for some people is that they experience mild to fairly intense allergic reactions to palo verde blooms. Symptoms can include itchy eyes, sneezing, nasal drip and congestion.

Palo verde trees are blooming across acres of hillsides and canyons around Tucson — basically everywhere you look.

This banner year can be credited to abundant rainfall — over 9 inches — in the sixth months preceding April.

Palo verde trees in brilliant bloom cloak the Catalina Foothills. -- Credit: Doug Kreutz/Arizona Daily Star

Expanding the canopy of trees in the metro area would require planting 300,000 trees each year, some of which would have to be on private land.

Palo verde blooms on a slope with saguaros. -- Credit: Doug Kreutz/Arizona Daily Star

 

Contact reporter Doug Kreutz at dkreutz@tucson.com or at 573-4192. On Twitter: @DouglasKreutz