On your way into the dunes did you notice any other plants? If not, watch for them as you return to your vehicle. Remember, the kinds of plants vary depending on your location in the dunes. The clumps of grass near the picnic tables are alkali sacaton (Sporobolis airoides). Approaching the tall dunes you may have seen large plants with small, shiny, smooth, dark green leaves—the creosote bush (Larrea tridentata). It has small yellow flowers, usually observed in springtime. Later, small, fuzzy, white balls containing seeds grow on its branches. The larger green or brown, walnut shaped growths on the branches are galls formed in response to an insect invader (midge). If you missed creosote bushes in the dunes, watch for them along the roadsides—they are common.
CREOSOTE BUSH
(Larrea tridentata)
Although the sand dunes seem dry, there is an underground reservoir providing moisture and nutrients for vegetation. The crusty mud playa acts as a cap and reduces evaporation of the underground water supply. Nearby, at Salt Creek, the same water flows on the surface as a stream during the winter and spring.
MESQUITE
(Prosopis glandulosa)
Most plants grow in the hollows between the dunes where they receive some protection from the wind and can reach water more easily. Yet, the mesquite tree (Prosopis glandulosa), probably the largest plant in sight, is often on top of the dunes. By slowing the wind with its branches, the mesquite causes sand to pile up in mounds beneath it. Sometimes sand completely covers a part of the tree causing branches to die. The sand then blows away, exposing those dead branches. Look for an example which illustrates this sand movement. Mesquite trees have thorns, so be careful. The mesquite tree loses its small, delicate leaves during winter. Its deep root system, growing 50-60 ft. (16-20 m) into the ground to reach fresh water, helps the tree survive. Some plants, such as saltbush, pickleweed, and mesquite seem incompatible because of different mineral and water requirements. However, these plants are able to live near each other because their roots are drawing moisture and nutrients from different levels of the soil. For example, in a rain forest, where the roots have ample water, most plant growth is above ground where competition is for sunlight. Whereas in a desert, where sunlight is abundant, competition for water is more critical. The root system of desert plants are highly developed, and each plant will find the optimum level in the soil suitable for its growth.
Mesquite tree: sand collector, food and shelter for animals and Shoshoni.
Be careful not to trample the roots as you explore the mound of sand near the mesquite tree—you may collapse a burrow—remember, you and the animals may be sharing the same shade.