shrubs characteristically have fleshy leaves and stems. Outside 

 California, this plant community is especially well developed in 

 the low areas around the Great Salt Lake in Utah. 



Because these low desert areas are frequently inundated with 

 water during the rainy season, a hard saline crust may form on 

 the soil surface when the soil is dry. In association with this soil 

 phenomenon, a curious symbiotic relationship has developed be- 

 tween local ant species and Alkali Sink plants. Ants bury seeds 

 below the surface in the process of carrying them to their nest 

 (or perhaps storing them) for use as food. This procedure results 

 in the seeds being planted below the hard surface crust at a level 

 where the salinity is lower and the moisture conditions are more 

 favorable to germination. 



Joshua Tree Woodland (Plate 15D;Map 4) 



Another desert community that is well known to many Cali- 

 fornians is the Joshua Tree Woodland, a plant community which 

 only marginally deserves the name "woodland". Joshua Tree is a 

 handsome tree-like yucca. Yucca brevifolia (Agavaceae). Common 

 associates of Joshua Tree are Mojave Yucca {Y. schidigera), juni- 

 pers (Juniperus spp.). Mormon tea (Ephedra spp.), cotton thorn 

 (Tetradymia spp., Compositae), CaUfornia Buckwheat (Eriogonum 

 fasciculatum, Polygonaceae), Bladder Sage (Salazaria mexicana, 

 Labiatae), box thorn {Lycium spp., Solanaceae), and many spe- 

 cies of the choUa cactus {Opuntia spp.). Rather few of the woody 

 plant species generally considered to be members of this plant 

 community are restricted to it. 



Joshua Tree Woodland occupies well-drained mesas and desert 

 slopes from Owens Valley to the Little San Bernardino mountains 

 and southern Nevada and Utah. It occurs at moderate elevations 

 from somewhat over 2,000 feet (610 m) to about 6,000 feet 

 (1829 m). The average annual rainfall is between 6 and 15 inches 

 (15 and 38 cm) depending on locality. Unlike most of the low- 

 land plant communities in California, Joshua Tree Woodland 

 receives occasional summer showers. The individual Joshua Trees 

 and associated junipers are rather widely spaced and are seldom 

 over 30 feet (9 m) high. Numerous shrubby plants in addition to 



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