Jack Dykinga / Close up of Saguaro cactus (Carnegiea gigantea) and Teddybear cholla (Cylindropuntia bigelovii) in evening light, Tucson Mountain Park, Arizona, USA

Tim Fitzharris / Teddy Bear Cholla (Cylindropuntia bigelovii) cacti in desert, Kofa Mountain, Kofa National Wildlife Refuge, Arizona

Floris van Breugel / Teddybear Cholla cacti (Cylindropuntia bigelovii) at sunset under a clearing storm over Anza Borrego State Park desert, California, USA, April.

Jack Dykinga / Teddybear Cholla cacti (Cylindropuntia bigelovii) in sunset light, Kofa National Wildlife Refuge, Arizona, USA

Tim Fitzharris / Teddy Bear Cholla (Cylindropuntia bigelovii) beneath the Superstition Mountain, Lost Dutchman State Park, Arizona

Rolf Nussbaumer / Teddy Bear Cholla Cactus (Cylindropuntia bigelovii) in field of Mexican Gold Poppy (Eschscholzia californica mexicana), Tonto National Forest, Bartlett Lake , Arizona, USA, March

Rolf Nussbaumer / Teddy Bear Cholla Cactus (Cylindropuntia bigelovii) in field of Mexican Gold Poppy (Eschscholzia californica mexicana), Tonto National Forest, Bartlett Lake, Arizona, USA, March

Sumio Harada / Teddy Bear Cholla (Cylindropuntia bigelovii) cactus surrounded with reproducting cholla balls, Sonoran Desert, Arizona

Philippe Clement / Loose joints of the Teddybear Cholla {Opuntia / Cylindropuntia bigelovii} drop readily and attach easily to passing animals, Organ Pipe National Monument, Arizona, USA

Philippe Clement / Teddybear Cholla {Opuntia / Cylindropuntia bigelovii}, Organ Pipe National Monument, Arizona, USA

Philippe Clement / Teddybear Cholla {Opuntia / Cylindropuntia bigelovii} in front of the Ajo Mountain Range, Organ Pipe National Monument, Arizona, USA May 2007

Shattil & Rozinski / Ocicat kitten {Felis catus} with teddybear

Jack Dykinga / Skeleton of Teddy Bear Cholla (Opuntia bigelovii) and Saguaro Cacti (CArnegiea gigantea) at sunrise, Cabeza Prieta National Wildlife Refuge, Arizona

Barry Mansell / White Throated Woodrat (Neotoma albigula) building nest in Bevertail cactus, bringing in teddybear cactus in his mouth. Arizona , USA

Patricio Robles Gil / Teddy Bear Cholla (Cylindropuntia bigelovii) and California Poppies (Eschscholzia californica) in the Sonoran Desert, Tucson, Arizona

Tim Fitzharris / Saguaro (Carnegiea gigantea) and Teddybear Cholla (Cylindropuntia bigelovii) cacti covering Panther and Safford Peaks, Saguaro National Park, Arizona

Tim Fitzharris / Saguaro (Carnegiea gigantea) and Teddybear Cholla (Cylindropuntia bigelovii) amid flowering Lupine and California Brittlebush (Encelia californica), Arizona

Tim Fitzharris / Saguaro (Carnegiea gigantea) and Teddybear Cholla (Cylindropuntia bigelovii) amid flowering Lupine and California Brittlebush (Encelia californica), Arizona

Tim Fitzharris / Saguaro (Carnegiea gigantea) and Teddybear Cholla (Cylindropuntia bigelovii) in front of the Picacho Mountains from Picacho Peak State Park, Arizona

Tui De Roy / Teddy Bear Cholla (Cylindropuntia bigelovii) in Sonoran desert landscape, Puerto Remedios, Sea of Cortez, Baja California, Mexico

Tim Fitzharris / Teddy Bear Cholla (Cylindropuntia bigelovii) under stormy skies, Joshua Tree National Park, California

Jim Brandenburg / Teddy Bear Cholla (Cylindropuntia bigelovii) and poppies, Organ Pipe National Monument, Arizona

Barry Mansell / Teddybear cholla cactus {Cylindropuntia bigelovii} Arizona desert, USA

Tim Fitzharris / Teddy Bear Cholla (Cylindropuntia bigelovii) cacti, Joshua Tree National Park, California