Jack Dykinga / Saguaro cacti (Carnegiea gigantea) in bloom with Foothill paloverde (Cercidium microphyllum) Sonoran Desert National Monument, Arizona, USA, April.

Jack Dykinga / Yellow paloverde (Cercidium microphyllum) flowering amongst Saguaro (Carnegiea gigantea). In foothills on north side of Santa Catalina Mountains, Coronado National Forest, Arizona, USA. May 2019.

Jack Dykinga / Yellow paloverde (Cercidium microphyllum) flowering amongst Saguaro (Carnegiea gigantea). In foothills on north side of Santa Catalina Mountains, Coronado National Forest, Arizona, USA. May 2019.

Jouan Rius / Rainbow over Saguaro cacti (Carnegiea gigantea), Organ Pipe Cactus (Stenocereus thurberi) and Foothills Palo Verde tree (Cercidium microphyllum), Organ Pipe Cactus National Monument, Sonoran Desert, A...

Jouan Rius / Yellow or Foothills Palo Verde tree (Cercidium microphyllum), Arizona, USA. April 2014.

Cyril Ruoso / Black-chinned hummingbird (Archilochus alexandri) feeding on Foothill Palo verde (Cercidium / Parkinsonia microphyllum) nectar, Vizcaino Desert, Baja California, Mexico, May.

Cyril Ruoso / Black-chinned hummingbird (Archilochus alexandri) feeding on Foothill Palo verde (Cercidium / Parkinsonia microphyllum) nectar, Vizcaino Desert, Baja California, Mexico, May.

Daniel Heuclin / Yellow Palo Verde / Foothill Palo Verde (Parkinsonia microphylla / Cercidium microphyllum) growing in habitat. Foothills of Santa Catalina mountains. Arizona, USA, September.

Philippe Clement / Foothill palo verde (Cercidium microphyllum) among rocks showing its smooth green bark, Saguaro NP, Arizona, USA 2007

Philippe Clement / Foothill palo verde (Cercidium microphyllum) showing its smooth green bark, Saguaro NP, Arizona, USA

Philippe Clement / Foothill palo verde (Cercidium microphyllum) among rocks showing its smooth green bark, Saguaro NP, Arizona, USA 2007

Philippe Clement / Saguaro cactus {Carnegiea gigantea} growing through branches of Foothill palo verde tree{Parkisonia / Cercidium microphyllum}, Sonoran desert, Arizona May 2007

Philippe Clement / Young Saguaro cactus {Carnegiea gigantea} growing through branches of Foothill palo verde tree {Cercidium / Parkinsonia microphyllum}, Sonoran desert, Arizona

Philippe Clement / Saguaro cactus {Carnegiea gigantea} growing through branches of Foothill palo verde tree {Cercidium / Parkinsonia microphyllum}, Sonoran desert, Arizona

Philippe Clement / Saguaro cactus {Carnegiea gigantea} growing through branches of Foothill palo verde tree {Cercidium / Parkinsonia microphyllum}, Sonoran desert, Arizona

Jack Dykinga / Saguaro {Carnegia gigantea}, Paloverde {Cercidium microphyllum} and Mesquite {Prosopis glandulosa} on cliffs of volcanic tuff, Hot Springs Canyon, Arizona, USA

Jack Dykinga / Saguaro cactus {Carnegia gigantea} flowering, Paloverde {Cercidium microphyllum} and Mesquite {Prosopis glandulosa} flowering on Bajada hillside, Hot Springs Canyon, Arizona, USA

Jack Dykinga / Saguaro cacti (Carnegiea gigantea) in flower beside flowering Foothills paloverde (Parkinsonia microphylla), Santa Catalina Mountains, Arizona, USA, May 2023.

Jack Dykinga / Saguaro cacti (Carnegiea gigantea) in flower beside flowering Foothills paloverde (Parkinsonia microphylla), Santa Catalina Mountains, Arizona, USA, May 2023.

John Cancalosi / Cactus wren (Campylorhynchus brunneicapillus) on Saguaro cactus (Carnegiea gigantea) in bloom with Palo verde (Parkinsonia microphylla) in background, Sonoran desert, Arizona. Photo showing Arizona...

Jack Dykinga / Saguaro cactus (Carnegiea gigantea) beneath Palo verde (Cercidium microphyllum) nurse tree, scorched by Big Horn Fire, a wildfire caused by a lightning strike on 5th June 2020 which burnt for six week...