Death Valley Expedition

Death Valley Expedition

(1891)

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The Death Valley Expedition was the first biological survey to commence from an 1890 act of Congress. The act appropriated funds to send expeditions to discover the geographic distributions of plants and animals in the United States.

Botanist Frederick Vernon Coville—the first curator of the U.S. National Herbarium—accompanied the expedition. He collected plants and, in accordance to the wishes of Congress, noted areas where different species flourished or faded. He organized his findings into a report entitled, “Botany of the Death Valley Expedition” where he defines the term “zonal plant” as a “species or variety which is of value in determining floral zones.” As the expedition progressed, “it was found to be the best method of procedure in a new area to establish the zones by means of a comparatively small number of the best zonal plants, and afterwards to arrange the other less important [plants] in their proper places,” Coville explains.

Naturalist Clinton Hart Merriam explicates on plant distributions in a separate expedition report entitled, “The Death Valley Expedition: A Biological Survey of Parts of California, Nevada, Arizona, and Utah” in which he wrote a “Report on Desert Trees and Shrubs” and a “Report on Desert Cactuses and Yuccas.” Merriam says that, “Most of the desert shrubs are social plants and are distributed in well-marked belts or zones, the vertical limits of which are fixed by the temperature during the period of growth and reproduction.” He explains that the zones ascended from the Lower Sonoran Desert to the desert ranges—including the Funeral and Charleston Mountains.

Merriam divides the Lower Sonoran Zone into three main belts. The lowest elevation contained a belt defined by the creosote bush Larrea tridentata, and Merriam judged this belt to be the best for growing citrus fruits, olives, and grapes. With increasing elevation, the Larrea belt ended and a belt defined by the distinctive spiny hopsage, Grayia spinosa, began. Lastly, came a belt of the true sage brush, Artemisia tridentata, which Merriam notes “spreads northward over the Great Basin like a monstrous sheet.”

In addition to documenting plant distributions, Merriam says that, “nearly all the species were photographed by me in the field, and in most instances parts of the individual plant photographed were brought back for positive identification.” Merriam collected many cacti from the genus Opuntia, which was abundant in the southwestern deserts. Opuntia echinocarpa was collected throughout the Mohave Desert and Merriam describes this species as having “inconspicuous green flowers.” He also states that two species of birds—LeConte’s thrasher and a cactus wren—almost always built their nests in this one species of cactus. Merriam found Opuntia basilaris in many locations throughout the Sonoran Desert and describes that it featured, “purple-red flowers that grow in great numbers on the upper edges of the pads, as many as eight open blossoms and several buds having been seen on a single pad at one time.”

Merriam notes that the rediscovery of Arctomecon californicum was “one of the most interesting incidents in the botanical line connected with the present expedition.” This yellow-flowered poppy was first discovered by John C. Frémont, but Merriam found the plant in the same location and on nearly the same day, only 47 years later. He also discovered a similar poppy, Arctomecon merriami, in the same location. The botanists of the Death Valley Expedition made significant contributions to the knowledge of plant distributions, and Coville dedicated the white-flowered poppy “to Dr. C. Hart Merriam as a token of his influence in the progress of geographic botany.”

References:

Coville, F.V. Botany of the Death Valley Expedition. Washington D.C.: Government Printing Office, 1893.



Humphrey, H.B. Makers of North American Botany. New York: The Ronald Press Co, 1961.



Merriam, C.H. The Death Valley Expedition: A Biological Survey of Parts of California, Nevada, Arizona, and Utah. Washington, D.C.: Government PrintingOffice, 1893.