Peniocereus greggii  Night Blooming Cereus
CACTUS.  Not found in the Empires yet, but recorded at Las Cienegas NCA to the south, in desert hills near Cienega Preserve to the north, and less than a quarter mile west of the upper end of Davidson Canyon.  Extremely difficult to see except when the fruits are ripe.  The wild plant pictured above is quite old, with several dead stems.  Flowers were photographed at Tohono Chul Park in Tucson.  Stems grayish green, sparsely branching, long and thin (less than 2 cm in diameter), semi-erect, growing from a large tuber.  Grows under mesquite, creosote bush, and other shrubs, which provide filtered shade and support for the stems.  Flowers very large (to 10 cm), fragrant, opening at dusk and lasting until dawn.  Flowers last only for one night, and all plants in the area bloom at once.  Pollinated by White-lined Sphinx moths.
FAMILY:  Cactaceae (Cactus Family)