Mojave Yucca (Yucca schidigera) in Joshua Tree National Park, California. Flowers of the Yucca genus -- which includes the Joshua Tree (Yucca brevifolia) -- depend on the small, white Pronuba Moth for pollination. This moth, in addition to gathering pollen, actually deposits her eggs in the ovary of the yucca flowers. The Pronuba larvae feed on the developing fruit, but leave some seeds to mature (DesertUSA).
Joshua trees (Yucca brevifolia) in Joshua Tree National Park, California.
Arches National Park