Claudio Contreras / Senita cactus (Lophocereus schottii) in Sonoran Desert, view to El Colorado volcano. El Pinacate Biosphere Reserve, Sonoran Desert, northwest Mexico. January 2009.

Jack Dykinga / Senita cacti (Lophocereus schottii) in the Pinacate and Grand Desert Biosphere Reserve, surrounding the border wall along the US-Mexican border through the Sonoran Desert in Arizona and Mexico.

Cyril Ruoso / Senita cactus (Pachycereus Lophocereus schottii) close up of flowers and spines, Vizcaino Desert, Baja California, Mexico, May.

Cyril Ruoso / Senita cactus (Lophocereus / Pachycereus schottii) flowering, at night, Vizcaino Desert, Baja California, Mexico, May.

Cyril Ruoso / Senita (Lophocereus schotti) flower with a bee searching for pollen, Vizcaino Desert, Baja California, Mexico, May.

Cyril Ruoso / Old Man Cactus (Lophocereus schotti) at night with open flowers, El Vizcaino Biosphere Reserve, Mexico

Cyril Ruoso / Old Man Cactus (Lophocereus schottii) spines with dew in early morning, El Vizcaino Biosphere Reserve, Mexico

Cyril Ruoso / Old Man Cactus (Lophocereus schottii) detail of spines, El Vizcaino Biosphere Reserve, Mexico

Cyril Ruoso / Old Man Cactus (Lophocereus schottii) flower with ant on night blooming flower, El Vizcaino Biosphere Reserve, Mexico

Tui De Roy / Old Man Cactus (Lophocereus schottii) in Sonoran desert landscape, Baja California, Mexico

Claudio Contreras / Senita cactus (Lophocereus schottii) in evening sunlight with El Colorado volcano in background, El Pinacate Biosphere Reserve, Sonoran desert, northwest Mexico.

Jeff Foott / Senita cactus (Pachycereus schottii). Baja California, Mexico.