MONTANA STATE This **cover" page added by the Internet Archive for formatting purposes 583*917 Nl Icsex 1992 -^ CONSERVATION STATUS OF KRIOGONL.M X L\(.01*l'S IN SOUTHERN CARRON COUNT\', MONTANA Prepared by: Peter Lcsica & Peter U. AchulT Montana Natural Heritage Program State l.ibrar) Building 1515 luist Sixth Avenue Helena, Montana 59620 Prepared Tor: USDI Bureau or I^iiid Management Montana State OITice P.O. Box 36800 Billings, M«)ntana 59107-6800 Januan 1992 ST;5Tr Dccu^:E:JTS ccimcr.::! TED 1 ^ 1991 MONTANA STATE LIBRARY 1515 C. 6lh AVE. HELENA. MOfirANA 'j9C20 n /io^ I'-i •p"j t-'H n e r^'-.- i Table of Omtents I. SPECIES INFORMATION I A. Classification 1 B. Present Legal or Formal Status 2 C. Description 3 D. Geographical Distribution 3 E. Habitat 4 F. Population Demography and Biologj' 7 G. Ecology S H. Lind Ownership y II. ASSESSMENT AND MANAGEMENT RECOMMENDATIONS ^ A. Threats to Known Populations y B. Management Practices and Response 10 C. Recommendations for Maintaining Viable Populations 1 1 D. Summary 1 1 III. LITERATURE CITED 12 IV. APPENDIX: Communications from Robert Dorn and James Reveal 14 V. PHOTOGRAPH 19 SPECIES INFORMATION A. CLASSIFICATION 1. SCIENTIFIC NAME: Eriogonum X lagopus Rydbcrg (Rvdberg 1917) 2. SYNONYMS: Eriogonum muiticcps Nccs ssp. canum Stokes (Stokes 1936), £. pauciflorum Pursh var. canum (Siokcs) Reveal (Reveal 1967), £. brcvicaulc Nutt. var. canum (Stokes) Dorn (Dorn 1988) 3. COMMON NAME: Rabbit buckwheat 4. FAMILY: Polygonaccac (Buckwheat Family) 5. GENUS: Eriogonum has approximately 150 species, all hut one of which are found in North America (Hitchcix'k et al. 1964). Annual members are relatively distinct based on minute characters, while perennial species are connected through series of intermediates and are often difficult to distinguish (Welsh et al. 1987). 6. SPECIES: The plant that we arc calling Eriogonum lagopus has a confusing taxonomic history. It was first described b>' Per Axel Rydbcrg (1917) in his Rockv Mountain Flora from specimens collected in Wyoming (Rydbcrg 1917). In 1936. Susan Stokes published Eriogonum multiccps ssp. canum based on material from Yellowstone County collected by Blankenship in 189(1 (Stokes 1936). In 1967. James Reveal decided that the Blankenship collection was better treated as Eriogonum pauciflorum var. canum and he also included a Tweedy specimen from Park County. .Montana in this taxon (Reveal 1%7). Sometime later. Reveal decided that both the Blankenship and Tweedy collections were the same as the type specimen for £. lagopus. Consequently, he placed both £. mult ice ps ssp. canum and £. pauciflorum var. canum in synonymy under E, lagopus since the latter was the first described taxon at the species level. In 1977, Robert Dorn placed E; lagc^pus and E; paucitlorum var. canum in synonymy under Eriogonum hrevicaule (Dorn 1977). Finally, in 1988. Dorn published the new combination E. hrevicaule var. canum and placed both E; multiceps ssp. canum and E. pauciflorum var. canum in synonymy under it (Dorn 1988; personal communication. Appendix A). Reveal reports that Eriogonum lagopus is a hybrid complex involving E. hrevicaule and E. pauciflorum (J. Reveal, personal communication; Appendix A). He believes thai the taxon is worthy of recognition at the species level. Welsh et al. (1987) recognize the commonness of hybridization in the E. brevicaule complex and treat such hybrids as varieties of E. brevicaule. Robert Dorn does not believe that this taxon is a hybrid and feels that it is better treated as a variety of E. brevicaule. We collected specimens that appear to be intermediate between E^ lagopus and E. mancum or E, pauciflorum. An additional difficulty in the taxonomy of this taxon arises because most specimens of E^ lagopus collected from Carbon County have hair on the perianth, while Rydberg's (1917) description of E, lagopus states that it has a glabrous perianth. In this report, we will continue to call this taxon Eriogonum lagopus. although this may well not be the correct name. B. PRESENT LEGAL OR FORMAL STATUS 1. FEDERAL STATUS a. U.S. Fish and Wildlirc Service: C-2; E. lagopus is a candidate for listing as a threatened or endangered species, but currently there is not enough information to make a decision on listing (USDI-FWS 1990). b. U.S. Bureau of Land Management: The Interim Draft Policy Regarding Sensitive Plants and Sensitive Plant Communities on BLM Lands in Montana lists E. lagopus as Special Status. Priority 1 in Montana. BLM will take no conscious action that will cause a species of special status to be listed as threatened or endangered. Priority 1 species may. after proper evaluation, be considered for Areas of Critical Environmental Concern (ACEC) or Research Natural Area (RNA). 2. STATE STATUS: Eriogonum lagopus is currently listed by the Montana Natural Heritage Program as globally rare and/or local (G3) and rare or local in Montana (S3). It is listed as a species of limited distribution in Montana by Lesica amd Shelly (1991). The.se state listings do not provide any direct legal protection for E. lagopus. DESCRIPTION 1. GENERAL NONTECHNICAL DESCRIPTION: Eriogonum lagopus is a perennial herb with a taproot and wo(xly branched rixMcrown. The clusters of basal leaves form small mats on the surface of the ground. The leaves are lance-shaped to narrowly sp(H>n-shaped tapering to a petiole ca. 1 inch long. The leaves are densely white- hairy beneath, less so abme; they are 1/2 to 2 inches long and less than 1/4 inch wide. The leafless erect stems are 2-5 inches tall and lcx)sely covered with long, white hairs. The umbrella-like inflorescence is 2-3 times branched. Each ultimate branch ends in a small cup-like involucre, ca. 1/6 inch long, with numerous flowers arising from inside. Each flower has 6 yellow petal-like tepals. less than 1/20 inch long with sparse long hairs on the outside. The anthers and anther stalks are yellow. 2. TECHNICAL DESCRIPTION: Perennial herb with a wtxHiy taproot and branching woody crown often forming small mats: leaxcs all or mainly basal; blades oblanceolaie to narrowly spaiulaic olicn with revolute margins. 1-6 cm long and 2-8 mm wide, densely white tomentose beneath, sparsely tomcnto%e to glabraie ab»>ve. tapcrmg gradually to a petiole 1-2 cm long: stems erect. 3-10 cm tall and loosely tomentose: inflorescence 2-3 limes branched and c\mc-liko. often with one small leaf-like bract and several small, often deciduous, scarious bracts at the base: rays of the inflorescence ascending: involucres tomentose. short-pedunculate, and ca. 4 mm long with triangular lobes: perianth yellow, not stipitaie, ca. 1 mm long, sparsely villous: filaments and anthers yellow (based on specimens at MONTU). 3. FIELD CHARACTERS: Eriogonum lagopus is somewhat similar to and appears to intergrade with two other species found in south- central Montana: £. pauciflorum and ^ mancum. The flowers of E. pauciflorum are white rather than yellow, and the inflore.scence of E. mancum is head-like rather than umbrella-like. GEOGR/\PHICAL DISTRIBUTION 1. RANGE: Eriogonum lagopus is known from Carbon County in south-central Montana. The type specimen is from near Custer in Yellowstone County, Montana (reported as Treasure County by Reveal 1967), and a second collection (Twee Jv 1 1 78 CAS) is from near Livingston in Park County, Montana (J. Reveal, personal communication; Appendix A). The plant is also known from Big Horn and Sheridan counties. Wyoming (Dorn 1988) 2. RECENTLY VERIFIED SITES: There are 41 documented locations for E. lagopus in the Pryor Mountain Desert area south and west of the Pryor Mountains in southern Carbon County. Montana (Figure 1). Most of these were recorded during a floristic study of this area in 1991 (Lesica and Achuff 1992). Lichvar et al. (1984) report that the plant is frequent on Bighorn Canyon National Recreation Area in Big Horn and Carbon counties, Montana and Big Horn County, Wyoming. Although these researchers did not map locations for the species, they undoubtedly collected a number of specimens that would vouch for populations in their study area. Exact locations of known populations are in Table 1. 3. HISTORICAL SITES: The Yellowstone County. Montana collection was made in 189() and the population has not been relocated. The Park County. Montana collection was probably made in the early 19()()'s and has not been relocated. HABITAT 1. ASSOCIATED VEGETATION: Eriononum lagc^pus always occurs on sparsely vegetated sites. Al the north end of the Bighorn Basin in Montana, it can be found in many different plant associations. It is most common in cushion plant grasslands dominated by Ceratoides lanatus. Gutierre^ia sar(^thrae. Chr\sothamnus nauseosus. Agropyron spicatum and Phlox spp. It can also be found in desert shrub communities including Artemisia arhuscula-Agropvron spicatum. Artemisia tridentata-Agropvron spicatum. and Atriplex confertifolia-Chrysothamnus nauseosus types. Occasional populations occur in open Utah juniper woodlands (Juniperus osteosperma/Agropvron spicatum). Other common associates include Arenaria hookeri. Astragalus adsurgens, A^ spatiilatus. Crvptantha cana, Hvmenoxvs acaulis. Machaeranthera grindelioides and Senecio canus. 2. TOPOGRAPHY: Eriogonum lagopus is most often found on moderate to steep slopes; however, it is also common on wind-swept ridge tops. Known sites in Carbon County, Montana range in elevation from 4,200 to 6,500 feet. Most sites are below 5,000 feet. s c X s 8 El c i u iZ Table 1. Location and size of Eriogonum lagopus populations with associated substrate. vegetation and elevation. T9S R28E S33 SW 100-1000 Chugwater Junost/Chrnau 4.150 T9S R28E S32 SE 100-1000 limestone Gutsar/Agrspi 4.150 T9S R27E S25 SE 100-1000 Chugwater Chrnau/Phlmus 4.400 T9S R28ES31 SW 100-1000 Chugwater Chrnau/Phlmus 4.4(K) T7S R25E S27 NW 100-1000 limestone Artarb/Agrspi 5.000 T9S R27E S28 NW >1000 Chugwater Cerlan/Agrspi 4,800 T9S R27E S15 SW 100-1000 caic shale Artarb/Agrspi 5.050 T9S R27ES15 SW <100 limestone Agrspi/Phlmus 4.900 T9S R26E S12 SW >1000 calc sandstone Artarb/Agrspi 5.400 T9SR26ES12SW >1000 limestone Agrspi/Phlmus 5.400 T9S R27E S19 NE >1000 ChugNvater Junost/Agrspi 5.150 T9S R25E S06 NE 100-1000 silly Artiri/Agrspi 4.450 TSS R24E S23 NW >10(K) shale Gutsar/Agrspi 4.4(M) TSS R24ES10NW >1000 sandy clay Chrnau/Agrspi 4,700 TSS R24E SIO NW 100-1000 silly (stony) Arttri'Agrspi 4.700 T7S R24E S19 NW >1000 sandy clay ChrnauAlonnui 4.100 T7S R24ES19NW 1(K)-1(KK) sandstone Pinlle/Artarb 4.250 T7S R24ES19SW >1000 sandy clay Yucgla/Agrspi 4.1(M) T7S R24E S32 NW >10(K) clay Chrnau/Atrdio 4.200 r7S R24E S32 NW >1(K)0 sandy clay Chrnau/Agrspi 4.2(M) T7S R24ES21 SW >1000 ChugNvater Chrnau/Agrspi 4.550 T7S R24ES15SE >1000 sandy clay Chrnau/Agrdas 4,750 T7S R24ES14SW >10(K) sandy clay Arttri/Agrspi 4.8(M) r9S R27E S25 SW 100-1000 Chugwater Arttri/Sticom 4.350 T9S R27E S13 SW >1000 calc sandstone Cerlan/Agrspi 5.2(K) T9S R27E S36 NW 100-1000 calc sandstone Cerlan 4.400 T9S R27E S36 NW 100-1000 Chugwater Junosi/Chrnau 4.400 T9S R28E S34 NW <100 Chugwater Junost/Artarb 4.500 T9S R28E S28 NW >1000 limestone Cerlan/Agrspi 4.900 T9S R28E S04 SE >1000 limestone Gutsar/Agrspi 6.500 r9S R28ES18SW 100-1000 calc sandstone Junost/Agrspi 5.200 r9S R28E S20 SE 100-1000 calc sandstone Junost/Cerled 4.500 T9S R28E S32 SW >1000 calc sandstone Cerlan/Agrspi 4,200 T9S R28ES31 NW >1000 Chugwater Yucgla/Oryhym 4,200 T9SR28ES31 NE >1000 Chugwater Junost/Erilag 4.2(K) T9S R28ES31 NE 100-1000 Chugwater Gutsar/Oryhym 4.350 T9S R27E S33 SW 100-1000 Chugwater Atrcon/Gutsar 4.700 T9S R27E S29 SW 100-1000 Chugwater Fhlmus/Agrspi 4..S()0 T9S R27E S29 NW 100-1000 Chugwater Junost/Gutsar 4.850 T9S R27E S29 SE 100-1000 limestone Fhlmus/Agrspi 4.S00 T9S R27E S29 SE >1000 Chugwater Phlmus/Agrspi 4.800 3. SOIL RELATIONSHIPS: Eriogonum lagopus is common on sandy clav soils derived from sandstone and shale and on sandv soil derived from Chugwaier sandstone. It also occurs on sandy soil derived from limestone and calcareous sandstone. It iKcurs most often in shallow or eroding soils. Most of these soils probably have an alkaline reaction and many are probably saline. 4. REGIONAL CLIMATE: The climate of southern Carbt^n County is semi-arid. Bridger. Montana, just north and west of the Pryor Mountain Desert, receives an average of 12.7 inches annual precipitation, and mean daily temperatures for January and July arc 2I.5T and 70.5T, respectively (NOAA I9S2). Ltncll.' Wyoming, on the east side of the Pryor Mountain Desert, receives an average ol 7.1 inches precipitation annually. Daily temperatures averagcil I6.8"F in January and 7I.8"F in July (Knight ei al. I9S7). Spring and early summer rainfall accounts for two-thirds of the annual precipitation, the balance coming as smnv (Knight el al. 1987). F. POPULATION DEMOGRAPHY AND BIOLOGY 1. PHENOLOGY: In southern Carbon County. F.riogonum lagopus flowers from mid-June through mid-July. In IWI. a very late \car. flowering did not really begin until early July and probably continued through late July. 2. POPULATION SIZE AND CONDITION: In southern Carbon County most populations of Eriogonum lagt^pus consist of more than 1(XX) plants and iKCupy several to hundreds of acres. Due to the extensive size of most populations, we did not attempt to estimate total population sizes. Estimates for £. lagopus density in 1.2-acrc plots in many of the populations are given in Table I. 3. REPRODUCTIVE BIOLOGY , a. T^TE OF REPRODUCTION: Production of seed is the only known method of reprcxluction in Eriogonum lagopus. b. POLLINATION BIOLOGY: The pollinator(s) of Eriogonum lagopus in southern Carbon County are not known. The umbellate inflorescence and small size of individual flowers suggest that E. lagopus may be serviced by generalized pollinators, such as flies and beetles, that crawl over the surface of the inflorescence as in members ol the Apiaceae (Faegri and van der Fiji 1971). it is also quite possible that Eriogonum lagopus is capable of self-pollination and produces a proportion of its seed by selfing. c. SEED DISPERSAL AND BIOLOGY: The fruit of Eriogonum lagopus is a small hard achene. These achenes may be dispersed by seed-gathering insects such as ants. In some cases, the dried perianth may remain around the achene and act as wings, similar to the fruits of some species of Rumex. In this case, the seeds would be dispersed by wind (van der Pijl 1982). d. SEEDLING BIOLOGY: Eriogonum lagopus occurs in a vcia arid region. Recruitment may be limited to years with prolonged periods of above-average precipitation. Few seedlings were observed in 1991. G. ECOLOGY 1. BIOLOGICAL INTERACTIONS: a. COMPETITION: Eriogonum lag(^pus occurs oni\ in spaiNc vegetation in very arid environments. Although plants in these sites are widely spaced, competition for water may be intense. It is unlikely that competition for nutrients or light is important. Halogeton glomeratus is an exotic annual that has become common at the north end of the Bighorn Basin. Hak)gcton glomeratus increases the salinity of the soil which favors its own seedlings (Sauer 1988). It is possible that as this invasiw species becomes more common in arid communities, ii could limit recruitment of native perennials in much the same way that Bromus tectorum competes with native vegetation in the steppes west of the Continental Divide (Mack 1981). b. HERBIVORY: We observed no evidence of herbivon.' from insects, wildlife or livestock. 2. HYBRIDIZATION: Hybridization among the perennial species of Eriogonum is common (Welsh et al. 1987). Two closely related species of Eriogonum co-occur with E. lagopus in southern Carbon County: E. paucitlorum and E. mancum. E, paucillorum is one of the putative parent species of E. lagopus. and backcrossing is not unexpected. We also obser\ed plants that appeared intermediate 8 between E, lact)pus and E^ mancun). In the vast majority of cases, populations of £. Ingopus did not show evidence of introgression with other species, e\en where two species occurred on the same site. II. Iw\ND ON^-NERSHIP 1. BUREAU OF LAND MANAGEMENT: In southern Cartxin County. Montana the majority of appropriate habitat and diKumenicd populations of Eriogonum lagopus arc on land administered by the Bureau of Land Management. 2. U. S. NATIONAL PARK SERMCE: Eriogonum l.itfopus is reported to be frequent in Bighorn Canyon National Recreation Area (Lichvar et al. 1984). These populations have not been mapped. 3. STATE OF MONTANA: One population of E: l-»tfopu< was hvaied on state land (T9S R27E S.V) NW! 4) during «nir IWI survey (Lesica and Achuff 1992). There are undoubtedly t)ther populaiit>ns on state land in the Prycw Mountain Desert area. 4. CROW INDIAN RESERVATION: It is likely that there are populations of Ei lagopus on the east side of the Bighorn River ow the Crow Reservation. There may also be populations on the west side of the river north of Bighorn Canyon N.R.A. Biological surveys have not been undertaken on the Crow Reservation iKcause ot tribal policy. 5. PRIVATE: Populations of Ei lng(^pus occur on deeded land at the head of Bridger Creek (T7S R24E S 19,20; T6S R24E SIS). Other populations probably occur on the Tillett Ranch (T9S R27E S23,26,35). II. ASSESSMENT AND MANAGEMENT RECOMMENDATIONS A. THRF-\TS TO KNOWN POPULATIONS: In southern Carbtin County. Montana populations of Eriogonum lagopus may be threatened by ( I ) exotic weed encroachment, (2) mining and oil and gas development, (3) oll- road vehicle use, and (4) livestock grazing. 1. EXOTIC WEED ENCROACHMENT: Hnlogeton uU^merntus is an Asian species that was introduced into arid western North America in 1934. It has since spread throughout much of the arid and semi- arid lands in the western U.S. It is poisonous to livesKKk .ind it outcompetes many native species by increasing the salinity of the soil (Sauer 1988). This plant has become common in the Pr\or Mountain Desert region and may be able to displace native plants including E. lagopus. However, at the present time there is no evidence that this is happening. Furthermore, E. lagopus is ver)' common and only a monumental increase in H. glomeratus could threaten its persistence. 2. MINING AND OIL AND GAS DEVELOPMENT: Bentonite claims have been made on public lands east of Warren. Although E^ lagopus does not generally occur on bentonite. it does occur in close proximity. Strip mining and associated road-building could damage nearby populations of E. lagopus. Oil and gas development has occurred in Wyoming four miles south of Warren. Future developments could threaten populations of F. lagopus. Bentonite mining and oil and gas development are localized in the Pryor Mountain Desert area, while p