|basalt desert buckwheat, Umtanum desert buckwheat|
|Reveal, J.L., F. Caplow, K. Beck|
|Edward Guerrant, Ph.D.|
The following Participating Institutions are custodians for this species in the CPC National Collection:
Rae Selling Berry Seed Bank & Plant Conservation Programs
University Of Washington Botanic Gardens
The conservation of Eriogonum codium is fully sponsored.
Edward Guerrant, Ph.D. contributed to this Plant Profile.
An ironic legacy of the Cold War is that some of the best remaining habitats for many native and endangered species are on military bases or other government properties. Artillery ranges, training grounds, and secure land surrounding bases, ammunition depots and other top-secret or dangerous areas have been closed to the public, and thus closed to development and grazing. The Hanford Nuclear Reactor in south-central Washington was built during World War II to produce and prepare the plutonium for the United States' first atomic bomb. The land surrounding the reactor was set aside as a security and safety buffer. Although the nuclear reactor has been decommissioned, the land surrounding the reactor has remained closed to the development and grazing.
The site that was once dedicated to producing plutonium, one of the most toxic substances known, has proved to be a blessing for native flora and fauna. Now, the Department of Energy's Hanford Nuclear Reservation, which straddles the Columbia River, contains some of the largest remnant areas of ungrazed and undeveloped shrub steppe in the Pacific Northwest. In 1994, The Nature Conservancy of Washington and the U.S. Department of Energy began the Hanford Biodiversity Project. The property was searched by scientists and a full inventory of plants, animals, and insects was compiled. Searches of this land revealed 30 rare plant taxa, three of which were new to science, including Eriogonum codium and Lesquerella tuplashensis (see profile on this web-site).
The only known population of Eriogonum codium occupies a narrow band that is 1.5 miles (2.5 km) long by less than 100 ft (30 m) wide. The plants occur on exposed basalt above steep cliffs and slopes, and are subjected to strong winds and a harsh environment (Reveal et al. 1995).
Distribution & Occurrence
Eriogonum codium grows only on a particular pumice-like substrate associated with a basalt flow along the ridge crest at 1100-1300 feet (340-400 m). It is found growing with Grayia spinosa, Salvia dorrii, Phacelia linearis, Cryptantha pterocarya, Camissonia minor, and Bromus tectorum
|As of 1997: 1 site with approximately 5000 adult plants, covering nearly 0.6 ha (Reveal et al. 1997).|
Conservation, Ecology & Research
Eriogonum codium is restricted to a particular basalt flow in a limited region of south-central Washington, possibly indicating a reliance on the chemical composition of the rock. The high water holding capacity of the basalt may also play a role (WNHP 1999). The pumice-like substrate is not continuous and plants occur in several discrete portions of the ridge (Dunwiddie et al. 2001).
The hypotheses for limited distribution includes substrate specificity, lack of competitive ability, and fire intolerance. While the first hypothesis is untested, researchers have failed to find other populations on outcroppings with same geology. High rates of seedling mortality may make establishment outside the present population a rare event. The survival of seedling to reproductive adults in areas with greater vegetation cover may also be limited due to competitive ability (Dunwiddie et al. 2001).
Fire appears to kill these slow growing plants. A hot burning fire in 1996 occurred in an area that was being monitored for Eriogonum codium. Some plants were entirely consumed and no traces remained that could be identified as E. codium. A conservative estimate is the fire may have killed 10-20% of the entire population. Overall, plants seemed to be very sensitive to heat and flames. The fire did not stimulate vigorous growth on any of the established plants. No seedlings were observed in burned areas. Mortality from the fire occurred primarily among plants growing with abundant vegetation cover that increased the fuel load. Introduction of Bromus tectorum in the 1900s likely increased vegetation cover and 1996 fire may have burned more extensively and intensively as a result (Dunwiddie et al. 2000).
Viable seed production is low. However, the abundant number of flowers produced may offset any negative affects of viability (Dunwiddie et al. 2000). Harvester ants have been observed carrying away seeds and thousands of seeds have been deposited at the entrance of ant burrows. However, it is speculated that ants play little role in dispersal, given the lack of seedlings found at refuse mounds. Instead they may simply remove a portion of the crop (Dunwiddie et al. 2000).
Fire (WNHP 1999). A 1996 fire killed approximately 20% of the adult plants in the population.
The non-native, invasive gras
Germination trials were conducted at The Berry Botanic Garden. Seeds were either cold stratified for 8 weeks or not cold stratified. The seeds were then subjected to either constant 68F (20C) or alternating 50/68F (10/20C). The highest germination percentage (86%) was achieved by cold stratification followed by alternating temperatures. Cold stratification followed by constant temperatures yielded 67% germination. Direct placement in constant temperatures yielded 50% germination while direct placement in alternating temperatures yielded only 17% germination (BBG File).
Candidate for Federal Listing.
Determine optimum germination requirements.
Determine propagation and reintroduction protocols.
Hall, J.A. 1998. Biodiversity inventory and analysis of the Hanford Site: 1997 Annual Report. Seattle, Washington: The Nature Conservancy of Washington.