Pollination of the endangered Arizona hedgehog cactus (Echinocereus arizonicus)

I studied pollination of the Arizona hedgehog cactus (Echinocereus arizonicus), an endangered plant species occurring in the Superstition Mountains, Arizona, in order to identify the pollinators of the species, determine whether the species is self-incompatible or pollen-limited, and evaluate whether individuals transplanted to make way for habitat disturbance continue to receive pollination. The flowers of E. arizonicus are large, bright red, and cup-shaped. Important flower visitors included hummingbirds and native halictid bees. Flower visitor guilds were similar between the wild population and the transplanted individuals (located in the Boyce Thompson Arboretum in Pinal County, Arizona), although the Arboretum is located at a low elevation and supports much higher abundances of flowering plants and pollinators than occur in the wild sites. Pollination treatments indicated E. arizonicus is highly self-incompatible but not pollen-limited and hummingbird visitation is relatively more important to seed set than is insect visitation but both contribute to total seed counts.