Friday, December 30, 2011

Crucifixion Thorn

While wandering through the desert during the annual Christmas Bird Count south of the Gila River near Buckeye, Arizona the other day, we came across one of three species of crucifixion thorn. All three are  mean spiky shrubs, with green stems and branches that take on the job of photosynthesis where leaves are mostly absent, except in very young plants. Out on the creosote flats of Robbin's Butte Wildlife Area, the lone specimen of Castela emoryi we found is the perfect place for resident loggerhead shrikes to impale their prey. This brand of crucifixion thorn is one of three Castela species native to the Sonoran Desert, but the only one found in Arizona wildlands; the others are found in Mexico. Over in southern California there is a Crucifixion Thorn Natural Area, dedicated to a healthy forest of this somewhat rare Castela. Like its better known cousin, Quassia, stems of Castela are sometimes used medicinally for their bitter tonic and intestinal parasite purging benefits.
The other two types of crucifixion thorn found in Arizona include Canotia holocantha, a very common tree-like shrub with long, flexible spine tipped branches, that grows mostly in the central uplands; and Koeberlinia spinosa, a well-armed shrub endemic to southwest deserts, ranging from California to Texas. None of these species, however, are native to the holy lands, where Jesus is said to have bore the corona de cristo for which these plants are named. The plant most likely to be referenced in biblical stories is Zizyphus spina-christi. We also have a thorny species of Zizyphus in Arizona, but we call it gray-thorn, among other things, in these parts.  Whichever you encounter, it's best to handle carefully with leather gloves, lest you draw blood!

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