Wee Thump Joshuas
by Bob Jaussaud
Sue is addicted to Facebook. Every morning she turns on her iPhone and opens Facebook to learn what has been happening with our friends and the world in general. Facebook has learned that Sue is interested in all things desert and appropriately on a recent morning it included a blurb about the relatively new wilderness area, Wee Thump, and the giant Joshua Trees found there. We knew we had to go ﬁnd them. So, with short notice and on the last day of 2020 we met Mignon and Robin in Searchlight and headed to Wee Thump in search of the giant Joshuas …and, thanks to Robin, to enjoy some ﬁne wine and hors d’oeuvres on the desert
Wee Thump means “ancient ones” in the Paiute language and it is the name given to a relatively new (2002) wilderness area in Nevada located a few miles west of Searchlight and just north of Hwy 164. The Wee Thump Wilderness was set aside to protect an ancient forest of Joshua Trees, some as old as 900 plus years. Joshua trees grow as little as 1/2 inch per year and some of them in the Wee Thump Wilderness are over 30 feet high.
The history and evolution of the Joshua Tree is truly unique. John C. Fremont described Joshua trees as “The most repulsive tree in the Vegetable Kingdom.” Indeed, they do kind of look like an agave on steroids. Early Mormons thought they saw the prophet Joshua’s silhouette, or perhaps his beard, in the tree. In fact, it is likely the Mormons were the ﬁrst to name the plant “the Joshua.” Before that (in the 1880’s) it was known as Yucca Palm” (Yes, that’s where the city of Palmdale gets its name). Other references to the plant include“palmyra cactus”, “cabbage tree”, “gray pilgrims”, “tree yucca”, “desert dagger” and more correctly the “Yucca brevifolia.”
Fortunately, on that last cold morning of 2020 we were able to ﬁnd giant Joshua Trees. In fact, lots of Joshua Trees of all sizes. They were not repulsive but quite beautiful and, as Sue reminded us, have a very unique relationship with the Yucca Moth. The Joshua Tree shares an obligate mutualism (symbiotic relationship) with the Yucca Moth. It seems this moth has evolved a unique mouthpiece that enables it to efﬁciently extract and hold pollen from the tree ﬂowers. With the gathered pollen it ﬂies to another Joshua ﬂower and uses its uniquely evolved ovipositor (rear end) to insert its eggs into the seed pack of the bloom. Then it pollinates the bloom so the seeds will grow and feed the moth’s baby caterpillars when they hatch. The caterpillars don’t eat all the seeds, so the Joshua Tree has pollinated seeds left over to reproduce with. Its a win-win for the moth and the tree. What’s really interesting is that Joshua Trees do not have nectar, so the moths are doing this specifically to pollinate the trees. None less than Charles Darwin wrote that this was the “most wonderful case of fertilization ever published.” Even more amazing is that now two distinct species of Joshua Trees have been identiﬁed and two distinct species of Yucca Moth have evolved to uniquely service each species.
Unfortunately, the future for this evolutionary miracle is threatened by climate change and other man made disasters such as the Cima Dome Fire. Cameron Barrows, an ecologist at UC Riverside, feels the Mojave Desert could lose up to 90 percent of its Joshua Trees before the end of the century. Tall mature trees do not necessarily show how healthy a Joshua Tree forest is.
It is the little juveniles that indicate the species is healthy and replacing itself. And, thankfully, we did ﬁnd some juveniles when we visited Wee Thump. So hopefully, if man can keep his mitts off it, that beautiful forest will survive for at least another 900 years. ~ Joeso