Species Profile: Yucca brevifolia

When Mormon settlers crossed the Mojave in the mid-19th century they "saw" the hands of Joshua reaching towards the heavens... so goes the origin of this tree's colloquial name. 

Joshua Trees (Yucca brevifolia) are a tree-like monocot plant that belong to the family Agavaceae. Although they are not true trees that produce growth rings with a woody core, this top heavy plant stretches nearly eleven meters towards the desert sky. The asymmetric branching and long spiky leaves remind me of the lonely acacias that dot vast stretches of the African savanna. Restricted to an altitude of 400 to 1800 meters, Joshua trees are an icon of the high desert. Their survival is contingent on adapting to the arid environment, and the plant's morphology reflects its evolution. A long taproot that seeks deep pockets of water, waxy leaves that prevent desiccation, and reproduction timed to ephemeral rains are an adaptive response to life in the desert. Following a heavy precipitation event, large clusters of fragrant white flowers (panicles) emerge and await their pollination. The pollinator is an obligate symbiont known as the pronuda yucca moth. Female moths will deposit eggs into the panicle and, in doing so, cross pollinate the trees. Larval moths feed on developing seeds and will emerge following metamorphosis. The yucca moth and Joshua tree coexist in a mutualistic relationship in which both the moth and tree benefit from their codependency.  
Joshua Tree National Park offers the landscape photographer an opportunity to produce unique images in a surreal environment. The high desert is a paradox ecologically and photographically. It is a sparse place that is seemingly void of life, yet it is both intricate and rich in its biodiversity. The photographer and ecologist must be very selective when choosing to study and capture this landscape. Having visited J. Tree National Park countless times, I suggest that you find a campsite deep within the park boundaries and enjoy the ambiance during the middle of the day. Be prepared to wake up early and stay up late, as the best light occurs before sunrise and after sunset. The abstract forms of the Joshua Trees make for incredible silhouettes, while the details of their bodies are beautifully recorded in the predawn light and afterglow of dusk.

Image #1: Star in Tree, Joshua Tree National Park. Canon 5D mark ii + 15mm Fisheye 
Image #2: Sunrise with Joshua, Joshua Tree National Park. Canon 40D + 17-85mm IS @ 17mm
Image #3: Panicle for Moths, Joshua Tree National Park. Canon 5D mark ii + 100-400mm IS L f4.5
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