Jack Dykinga / Hairy bird's foot morning glory (Ipomoea leptotoma) flower over Prickly pair (Opuntia sp) Catalina State Park, near Tucson, Arizona, USA, August.

Floris van Breugel / Beavertail cactus (Opuntia basilaris) in otherwise stark desert, Alabama Hills, Owen's Valley, California, USA May

Tim Fitzharris / Plains Pricklypear (Opuntia polyacantha), Arches National Park, Utah

Karine Aigner / Western diamondback rattlesnake (Crotalus atrox) coiled up at base of Prickly pear cactus (Opuntia sp). Texas, USA. April.

Jack Dykinga / Santa Rita prickly pear (Opuntia santarita) cactus flower with new growth spines on pad. Santa Catalina mountains foothills, Upper Sonnoran Desert, Arizona, USA. May.

Jeff Foott / Plains Pricklypear (Opuntia polyacantha) cactus flowering, Arches National Park, Utah

Jeff Foott / Plains Pricklypear (Opuntia polyacantha) cactus flowering, Arches National Park, Utah

Jeff Foott / Plains Pricklypear (Opuntia polyacantha) cactus flowering, Arches National Park, Utah

Nick Upton / Walled fields of Prickly pear / Barbary fig (Opuntia ficus-indica) on volcanic soil, formerly harvested for Cochineal insects (Dactylopius coccus), with Monte Corona volcanic peak in the background, n...

John Chan / Mourning dove (Zenaida macroura) perched on a Coastal pricklypear (Opuntia littoralis), avoiding the spines as it takes flight, Southern California, USA, April.

Nick Hawkins / Galapagos prickly pear (Opuntia echios), a vulnerable species. Isabela Island, Galapagos.

Nick Hawkins / Common cactus finch (Geospiza scandens) perched on Prickly pear (Opuntia). San Cristobal Island, Galapagos.