While walking with Mary Klinkel along the main Sabino Canyon road the other day, she noticed an odd patch of plants. They are the root parasite Orobanche cooperi, with the English name Burro-weed Strangler or Desert Broomrape.
|Photos by Fred Heath 2/16/2015|
To my knowledge, all of the members of the Orobanchaceae family can be root parasites. Recently plants in the genus Castilleja (paintbrushes and owl clovers) were added to this family. Orobanche cooperi which has no chlorophyll is considered an obligate parasite because it cannot complete its life cycle without a host plant.
Common host plants for this plant are in the Sunflower Family especially the Ambrosia genus (such as Canyon Ragweed, Triangleleaf Bursage, and Burro Brush in Sabino) and Encelia (Brittlebush). These Orabanche plants were all somewhat near to Brittlebushes and thus is host plant for those in the photos.
|close up of flower|
Note that the paintbrushes and owl clovers which have leaves containing chlorophyll are able to make their own food and don’t necessarily need a host plant (so they are not obligate parasites). Owl clover will sometimes use lupines as a host and the reason that you might find lots of owl clover in fields of lupine (like in Catalina State Park).
Thanks, Fred and Mary, for another great find!