Agave, Agave americana.

Joshua tree, Yucca brevifolia.

Joshua tree, Yucca brevifolia.

Joshua tree, Yucca brevifolia.

Greece, Flowering stems of Agave cultivar silhouetted against pale sky.

Greece, Detail of sharp spines of Agave cultivar.

USA, Arizona, Saguaro National Park, Saguaro cacti against blue sky.

USA, Arizona, Saguaro National Park, Saguaro cactus against blue sky.

USA, Arizona, Saguaro National Park, Saguaro cactus with raised ridged branches against blue sky.

USA, Arizona, Saguaro National Park, Saguaro cactus silhouetted against blue sky in soft light, framed by branches of another in foreground.

USA, Arizona, Saguaro National Park, Ridged branches of Saguaro cactus against blue sky.

USA, Arizona, Saguaro National Park, Ridged branches of Saguaro cactus against blue sky.