Joshua Tree Yucca brevifolia Engelm. Agavaceae Species description Joshua trees are tall, irregular, branched desert yuccas, columnar when young and maturing with open, rounded crowns and wide, spreading branches. The thick branches are tipped with rosettes of dagger-like leaf blades. Joshua tree trunks are fibrous, and may measure 1-3 feet in diameter. The leaves, or blades are dark to blue-green, wider at base and tapering to a sharp point. Flowers are white to cream-colored, elliptoid to globose, and densely packed in erect or rounded clusters borne at the branch tips. The flowers bloom in spontaneous bloom events that may occur between March and May. The fruit is an ellipsoid capsule, green when young, and drying to a light tan color. Each fruit contains 30-50 flattened black seeds. Natural and cultural history Joshua trees are endemic to the Mojave Desert, and their range follows the desert’s boundaries in southern Nevada, southwestern Utah, western Arizona, southeastern California, and the northern Baja California peninsula of Mexico. They grow on dry habitats in desert valleys and hillsides from 3,000-7,000 feet in elevation. Native peoples in the Mojave Desert used Joshua trees for food and fiber. They roasted the flowers, and ate the seeds raw or ground into mash and cooked. The roots were used to make a dye. Planting considerations and propagation techniques Joshua trees usually grow 20-40 feet tall with a canopy diameter of 15-30 feet. They are very spiny, so take care when planting them in public places. They have been known to live for over 150 years. Joshua trees prefer full sun exposure and are frost tolerant to -13º F. The flowers are pollinated by the yucca moth, and must be cross- pollinated to make fruit or viable seed. Joshua tree thrives in any soil, but prefers a sandy loam. The seeds germinate easily and do not need treatment. Sow in spring. Germination may be easier if seeds are soaked 24 hours prior to sowing. Water needs Joshua trees have very low water needs once established. Care Joshua trees require minimal attention once established, though the trees may be shaped for safety and to facilitate site access. Harvesting and processing The flower clusters, before the buds open, can be parboiled in salt to remove bitterness, drained, cooked again and served like cauliflower. The open buds and flowers are rich in sugar, and can be roasted and eaten. The roots may be eaten raw, boiled, or roasted; the roots do contain saponins, which are toxic, but are broken down by prolonged heat, such as oven roasting. Joshua tree seeds are also edible. References and resources Gucker, Corey L. 2006. Yucca brevifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/plants/tree/yucbre/all.html [2017, February 7]. Ladybird Johnson Wildflower Center. Native Plants Database (NPIN). 2015. Yucca brevifolia. http://www.wildflower.org/plants/result.php?id_plant=YUBR Plants for a Future (PFAF). Yucca brevifolia – Engelm. http://www.pfaf.org/USER/Plant.aspx?LatinName=Yucca+brevifolia Useful Tropical Plants. n.d. Yucca brevifolia. http://temperate.theferns.info/plant/Yucca+brevifolia 2 .