Thorne s Buckwheat (Eriogonum thornei)

Thorne s Buckwheat (Eriogonum thornei) Legal Status Taxonomy State: Endangered; S1.1 1 California Rare Plant Rank: 1B.2 2 Federal: Bureau of Land Photo courtesy of Hartmut Wisch. Management Sensitive Critical Habitat: N/A Recovery Planning: N/A Notes: Previously a candidate for federal listing (58 FR 64828 64845) but was removed from candidacy on February 28, 1996, in a notice of review (61 FR 7597 7613). Thorne s buckwheat (Eriogonum thornei) was originally described by Reveal and Henrickson (1975) as Eriogonum ericifolium var. thornei and was reclassified as Eriogonum thornei in 1998 (Shultz 1998; IPNI 2005). The taxonomic revision was intended to more accurately reflect phylogenetic relationships based primarily on species distribution: the two other varieties of E. ericifolium (ericifolium and pulchrum) are associated with the Colorado Plateau in Arizona, while Thorne s buckwheat is associated with the Mojave Desert in California (Shultz 1998). Thorne s buckwheat is in the Polygonaceae family (Jepson Flora Project 2011). It is small perennial shrub approximately 0.4 to 1 decimeters (1.6 to 3.9 inches) in diameter. A full physical description of the species can be found in the Jepson Flora Project (2011). 1 S1: Critically imperiled; X.1: Very threatened. 2 1B: Rare, threatened, or endangered in California and elsewhere; X.2: Fairly endangered in California. 1 March 2012

Distribution General There are two occurrences recorded in the California Natural Diversity Database (CNDDB) (CDFG 2012). Thorne s buckwheat is known from Fourth of July Canyon along a ridge southeast of Cliff Canyon Spring in the New York Mountains in San Bernardino County (Reveal and Henrickson 1975; Reveal 1989). The type locality lies within the Mojave National Park and a second occurrence (which may be a mis-mapping of the type locality) is recorded a tenth of a mile to the northeast within BLM land (CDFG 2012; Figure SP-P32). This species occurs at elevations from 1,800 to 1,830 meters (5,400 to 5,490 feet) (CNPS 2011). Distribution and Occurrences within the Plan Area Historical The type locality was first recorded in 1973 and lies within the Mojave National Park and is also the only recent occurrence in the CNDDB, as discussed below. A second occurrence dates from 1979 (and which may be a mis-mapping of the type locality) is recorded a tenth of a mile to the east within BLM land (CDFG 2012; Figure SP-P32). Figure SP-P32 shows the type locality as a recent occurrence. Recent The type locality was last seen in 2008 and the record last updated in 2009 (CDFG 2012). The second occurrence has not been seen since first reported in 1979 and may be a mis-mapping of the type locality. As reported above, the type locality occurs within the Mojave National Park and the second occurrence lies within BLM property (CDFG 2012; Figure SP-P32). 2 March 2012

Natural History Habitat Requirements Thorne s buckwheat grows in pinyon and juniper woodland communities on gravelly substrates (see Table 1; Reveal and Henrickson 1975; CNPS 2011). The type locality occurs on a northwest southeast trending ridgeline. The pinyon and juniper woodland at the type locality included Utah juniper (Juniperus osteosperma), pinyon pine (Pinus monophylla), banana yucca (Yucca baccata), prickly pear (Opuntia spp.) and other shrubs, as well as an understory of Wright s buckwheat (Eriogonum wrightii var. wrightii), Nevada onion (Allium nevadensis var. cristatum), blue grama (Bouteloua gracilis), rough menodora (Menodora scabra), fineleaf hymenopappus (Hymenopappus filifolius var. eriopodus), and viviparous foxtail cactus (Coryphantha vivpara var. rosea) (Reveal and Henrickson 1975). The soils are sandy loam on quartz monzonite and are high in copper (300 ppm) (CDFG 2012; Reveal and Henrickson 1975). The second occurrence (which may be a mis-mapping of the type locality) is simply listed as occurring along a dirt road near mine shafts (CDFG 2012). Table 1. Habitat Associations for Thorne s Buckwheat Land Cover Type Pinyon and juniper woodland Habitat Designation Primary Habitat Parameters Gravelly substrate (high copper concentrations may be important (300 ppm)); 1,800 1,830 meters (5,400 5,490 feet) Supporting Information CNPS 2011; CDFG 2012; Reveal and Henrickson 1975 Reproduction Thorne s buckwheat is a perennial shrub that blooms from July to August (CNPS 2011; Jepson Flora Project 2011; Reveal 1989). There is no information available regarding pollinators, seed germination, seed dispersal, or seedling establishment. 3 March 2012

Ecological Relationships As described in Habitat Requirements, Thorne s buckwheat is associated with pinyon and juniper woodland communities on gravelly substrates (CNPS 2011). This species has a very limited geographic distribution and little is known of its life history and ecological relationships. Information regarding pollination, seed germination, dispersal, or seedling establishment has not been reported for this species. Population Status and Trends Global: Critically Imperiled (CNPS 2011) State: Same as above Within Plan Area: Same as above Thorne s buckwheat is known from two occurrences in Fourth of July Canyon. Abundance at the type locality varies from locally abundant in 1973, to more than100 plants observed in 1981, to very localized in 1983, to 1,500 plants observed in 2005, to an unknown number of plants in 2008. There is no abundance information for the second occurrence (which may have been a mis-mapping of the type locality) (CDFG 2012). The plant seems to be persistent at the type locality although factors affecting abundance have not been identified. Threats and Environmental Stressors Information regarding threats and environmental stressors has not been reported for this species. This species is tolerant of high (300 ppm) copper levels in the soil (CDFG 2012; Reveal and Henrickson 1975). Conservation and Management Activities The type locality occurs within the Mojave National Park and the second occurrence (likely a mis-mapping of the type locality) occurs on BLM land (CDFG 2012). There is no information on the management of Thorne s buckwheat by the National Park Service or the BLM; however, the occurrences are presumably afforded some protection from development based on land ownership. 4 March 2012

Data Characterization The general distribution of Thorne s buckwheat is well known based on its very limited geographic distribution (Fourth of July Canyon). Little is known regarding the species pollination, seed germination, seed dispersal, and recruitment, but the population appears to be stable or increasing (CDFG 2012). Management and Monitoring Considerations Protection should focus on the two currently known occurrences in Fourth of July Canyon, one of which occurs in the Mojave National Park and one of which occurs on BLM land (CDFG 2012). Additional surveys to confirm the suspected second occurrence, as well as to identify additional occurrences in the area, would be useful. Predicted Species Distribution in Plan Area Literature Cited Species model summary and results will be provided following model development. CDFG (California Department of Fish and Game). 2012. Eriogonum thornei. Element Occurrence Query. California Natural Diversity Database (CNDDB). RareFind, Version 4.0 (Commercial Subscription). Sacramento, California: CDFG, Biogeographic Data Branch. Accessed February 2012. http://www.dfg.ca.gov/biogeodata/cnddb/mapsanddata.asp. CNPS (California Native Plant Society). 2011. Eriogonum thornei. Inventory of Rare and Endangered Plants (online edition, v8-01a). Sacramento, California: California Native Plant Society. Accessed May 2011. http://www.cnps.org/inventory. IPNI (International Plant Names Index). 2005. Plant Name Details: Eriogonum thornei. Accessed May 2011. http://www.ipni.org/ipni/idplantnamesearch.do;jsessionid=7 89C6A9CE58E82A4A5CDD58F55FEA200?id=1002396-1&back_page=%2Fipni%2FeditSimplePlantNameSearch.do%3 5 March 2012

Bjsessionid%3D789C6A9CE58E82A4A5CDD58F55FEA200%3 Ffind_wholeName%3Deriogonum%2Bthornei%26output_for mat%3dnormal. Jepson Flora Project. 2011. Eriogonum thornei. The Jepson Online Interchange: California Floristics. Berkeley, California: University of California. Accessed May 2011. http://ucjeps.berkeley.edu/interchange.html. Reveal, J.L. and J. Henrickson. 1975. A New Variety of Eriogonum Ericifolium (Polygonaceae). Madroño 23(4):205 209. Reveal, J.L. 1989. The Eriogonoid Flora of California (Polygonaceae: Eriogonoideae). Phytologia 66(4):295 414. Accessed June 6, 2011. http://www.biodiversitylibrary.org/item/47411. Schultz, L.M. 1998. A New Species of Eriogonum (Polygonaceae: Eriogonoideae) from Utah and Nevada. Harvard Papers in Botany 3(1):49 52. 6 March 2012

Species Range in California Utah Nevada!( Current Occurrence Point!( Historic and Unknown Occurrence Point Note: Occurrence point size graphically represents the precision level code for the data point but is not scaled geographically.!(!(!(!( Arizona P a c i f i c O c e a n Z:\Projects\CEC\j_DRECP\MAPDOC\MAPS\BaselineBioReport\SpeciesProfiles I 0 12.5 25 Miles Sources: DRECP Species Occurrence Database (2011), CWHR (2008), CEC (2010), USGS (2010), ESRI (2010) Desert Renewable Energy Conservation Plan (DRECP) Baseline Biology Report MEXICO FIGURE SP-P32 Thorne s Buckwheat Occurrences in the Plan Area (N=4)