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The Hunt for the Westernmost Saguaro

Posted: Tue Apr 03, 2012 11:00 pm
by Chris
Its gangly silhouette has become synonymous with the entire American West, but the iconic saguaro is actually native to a fairly small area. Despite the label on your Tex-Mex salsa, there are no saguaros in Texas unless they're in botanic gardens or in pots. A stylized saguaro graces the sign of the Cactus Cafe in Wall, South Dakota, but South Dakota is 800 miles from the nearest wild saguaro. Colorado? Nevada? New Mexico? No tienen saguaros.

In fact, the species' range covers about two thirds of the state of Sonora, Mexico, and the southwest third of the state of Arizona, and that is pretty much it excepting one small population in California's Whipple Mountains, in the easternmost part of the state, and an even smaller population in Imperial County. I've come to the Palo Verde Mountains in Imperial County to look for more.
The Hunt for the Westernmost Saguaro

Re: The Hunt for the Westernmost Saguaro

Posted: Wed Apr 04, 2012 12:00 pm
by Don
Chris
I have often noticed in my California/Nevada-Arizona border crossing that Saguaro AND Joshua Trees seem to be border conscious. I didn't know about the Whipple Mountain and Imperial County Saguaros (not many are familiar with those locations, huh!). I do know, on the Joshua Tree side, that there is a disjunct community of JTs in western Grand Canyon.
Why? It's easy to surmise that the Colorado River creates a biogeographical constraint...perhaps the reproductive vector is not airborne? Moths can't fly far enough to cross a river? Who knows? Somebody must have studied this issue!
-Don

Re: The Hunt for the Westernmost Saguaro

Posted: Thu Apr 05, 2012 11:15 pm
by Chris
I would imagine the Saguaro would be limited also by the weakening of the Monsoon as you get further west. They have pretty short roots IIRC and need more spread out rainfall than the winter dominated stuff of California. Maybe, reversed Joshua Tree is just out competed in most places in AZ. NW is the least monsoon influenced.

But, you have a point about the Colorado River. I recall some pretty good Saguaro populations on the AZ side down near Parker, Quartzite, but absent just on the other side.