Suzi Eszterhas / Digger Bee (Melissodes sp) pollinating Engelmann Prickly Pear (Opuntia engelmannii) flower, Red Corral Ranch, Texas

Jack Dykinga / Engelmann spruce (Picea engelmannii) growing amongst pinnacles of volcanic tuff, dawn, Wheeler Geological Area Wilderness, Rio Grande National Forest, Colorado, USA

Sumio Harada / Red Squirrel (Tamiasciurus hudsonicus) separating seeds from an Engelmann Spruce (Picea engelmannii) cone to store for winter food, Rocky Mountains, Alberta, Canada

Cyril Ruoso / Engelmann Prickly Pear (Opuntia engelmannii) cactus in rain, southern Texas

Cyril Ruoso / Engelmann Prickly Pear (Opuntia engelmannii) cactus blooming at night, southern Texas

Cyril Ruoso / Engelmann Prickly Pear (Opuntia engelmannii) cactus flower buds, southern Texas

Cyril Ruoso / Ant (Formicidae) on Engelmann Prickly Pear (Opuntia engelmannii) cactus, southern Texas

Cyril Ruoso / Ant (Formicidae) on Engelmann Prickly Pear (Opuntia engelmannii) cactus, southern Texas

Alan Watson / Engelmann spruce tree (Picea engelmannii), Alpine paintbrush flowers (Castilleja rhexifolia) and other flowers including Beargrass, in alpine meadow along the Rockwall trail, Kootenay National Park, B...

Alan Watson / Engelmann spruce tree (Picea engelmannii), Alpine paintbrush flowers (Castilleja rhexifolia) and other flowers including Beargrass, in alpine meadow along the Rockwall trail, Kootenay National Park, B...

Alan Watson / View to Helmet Falls with forest of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa), Kootenay National Park, British Columbia, Canada. World Heritage Site Helmet Falls at 1,...

Alan Watson / View to Helmet Falls with forest of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa), Kootenay National Park, British Columbia, Canada. World Heritage Site Helmet Falls at 1,...