flowering phenology of the saguaro

07 Jun flowering phenology of the saguaro

The saguaro, (Carnegiea gigantea), is a giant columnar cactus that can grow up to 15 m tall and weigh several tons, of which at least 85% of the mass is water. This is the most common cactus species in Saguaro National Park and the one I’ll be working on the most this summer. The saguaro produces a beautiful white flower each spring that is pollinated by birds, insects, and bats. With increasing temperatures in the past century, the blooming of these flowers may happen earlier in the year, causing the saguaros to be out of sync with pollinators.

Part of my work here is to go out to the field almost every day to photograph the buds, flowers, and fruit of saguaros all over the west and east side districts of the park. We use a GoPro that is mounted on top of a 30 foot long “selfie stick” to take the pictures.  We also take height measurements of the saguaros and record the cardinal direction in which flowers, buds and fruits are located. An interesting observation has pointed out that flowers are starting to grow on the side of the saguaro rather than the crown or top center. We want to find out how the side flowering varies across the landscape in Saguaro National Park and if there is a “side” preference where the flowers occur. One of our goals is to couple the flowering dates with meteorological and past data to learn more about these patterns and learn more about potential drivers affecting the flowering phenology of the saguaro. Can’t wait to share what we find out !