Rare Plants of Idaho
Rare Plants of Idaho. Published by the Bureau of Land Management (BLM).
U.S. Department of the Interior Bureau of Land Management | Idaho Rare Plants of Idaho Front cover: Astragalus amnis-amissi, flowers, Lynn Kinter (IDNHP) U.S. Department of the Interior Bureau of Land Management | Idaho Rare Plants of Idaho Idaho State Office 1387 S. Vinnell Way Boise, ID 83709 Written by Michael Mancuso, Anne Halford and Karen Colson March 21, 2019 Copies available from the BLM Idaho State Office BLM DISTRICT AND FIELD OFFICES IN IDAHO SCALE: 0 50 100 miles LEGEND DISTRICT BOUNDARY DISTRICT OFFICE LOCATION with colocated field office Coeur d'Alene Field Office Field Office Boundary Field Office Location Washington Public Land: BLM-Administered NORTH COEUR D’ALENE DISTRICT Cottonwood Field Office M on ta na Salmon Field Office Challis Field Office IDAHO FALLS DISTRICT Upper Snake Field Office BOISE DISTRICT Owyhee Field Office ii Shoshone Field Office TWIN FALLS DISTRICT Bruneau Field Office Nevada Wyoming Oregon Four Rivers Field Office Jarbidge Field Office Pocatello Field Office Burley Field Office Utah CONTENTS 1 INTRODUCTION Idaho Distribution Maps Taxonomy Conservation Category and Rank Definitions Glossary of Acronyms Used in the Field Guide 5 BLM DISTRICT AND FIELD OFFICE SPECIES GUIDE 9 13 17 21 25 31 35 41 45 49 53 57 63 69 73 77 81 85 89 93 99 105 109 115 119 123 SPECIAL STATUS PLANT SPECIES Abronia mellifera var. pahoveorum Allium aaseae Astragalus ambyltropis Astragalus amnis-ammissi Astragalus anserinus Astragalus aquilonius Astragalus asotinensis Astragalus atratus var. inceptus Astragalus jejunus var. jejunus Astragalus mulfordiae Astragalus oniciformis Astragalus packardiae Astragalus sterilis Calamagrostis tweedyi Carex aboriginum Carex idahoa Castilleja christii Chaenactis cusickii Eriogonum capistratum var. welshii Howellia aquatilis Lepidium papilliferum Mentzelia mollis Mirabilis macfarlanei Monardella angustifolia Oenothera psammophila Oxytropis besseyi var. salmonensis iii 127 137 141 145 151 157 163 167 Phacelia inconspicua Pinus albicaulis Polemonium elusum Silene spaldingii Spiranthes diluvialis Stanleya confertiflora Thelypodium repandum Trifolium owyheense 170 180 182 ASSOCIATED SPECIES LIST ACKNOWLEDGEMENTS AND REFERENCES ILLUSTRATIONS iv INTRODUCTION Idaho Bureau of Land Management (BLM) staff need information about Special Status Plant Species to assist with field surveys, setting data collection priorities, making conservation management decisions, and assessing conservation actions. To meet this need, the Idaho BLM State Office has initiated a project to produce an on-line field guide to Idaho BLM Special Status Plant Species. The purpose of this webbased field guide is to help users recognize and identify Special Status Plant Species in the field. The first installment includes 35 Special Status Plant Species. Additional taxa are planned for the future. The guide provides one-stop access to general description, field identification tips, and similar-looking species summaries, as well as basic taxonomic, conservation status, distribution, habitat, and phenology information. The field guide also includes an Idaho distribution map and color images for each species. The field guide is intended to assist agency, academic, consultant, and other biologists charged with conducting field surveys or other conservation-related work for Special Status Plant Species in Idaho. The field guide can also serve members of the public and citizen scientists interested in learning more about Idaho BLM Special Status Plants Species. The guide’s digital, on-line format allows for ready down-loading of hard copies that can be taken into the field or shared with colleagues. Making the guide available in a digital format will enable the species account information to reach a wider audience and be available more quickly compared to print media. The digital format also makes it easier to add more species accounts in the future and to update information about the species already in the guide in a more timely and inexpensive manner. Idaho Distribution Maps Idaho distribution maps in the field guide are based on Element Occurrence locations for each species in the Idaho Fish and Wildlife Information System database (Idaho Department Fish and Game 2018). Distributions are mapped at the Township scale; each Township depicted on the map contains one or more Element Occurrence locations. Occupied Townships are shaded red on the distribution maps. 1 Taxonomy Scientific plant names in the field guide follows the Flora of the Pacific Northwest, 2nd Edition (Hitchcock and Cronquist 2018). Nomenclature for species not included in this book follows the Intermountain Flora (Cronquist et al. 1972, Cronquist et al. 1977, Cronquist et al. 1984, Cronquist 1994, Barneby 1989, Cronquist et al. 1997, Holmgren et al. 2005, Holmgren et al. 2012). Conservation Category and Rank Definitions The field guide includes BLM conservation category and NatureServe conservation status ranks for each Special Status Plants Species. BLM Special Status Plant Species Conservation Categories Type 1: Federally listed as threatened and endangered. Type 2: Rangewide/Globally Imperiled Species - High Endangerment. These are species that have a high likelihood of being listed in the foreseeable future due to their global rarity and significant endangerment factors. This category also includes USFWS Proposed and Candidate species, Endangered Species Act (ESA) species delisted during the past 5 years, ESA Experimental Non-essential species with ESA Proposed Critical Habitat. Type 3: Range-wide or State-wide Imperiled - Moderate Endangerment. These are globally rare or very rare in Idaho, with moderate endangerment factors. Their global or state rarity and the inherent risks associated with rarity make them imperiled species. Type 4: Species of Concern. These are generally rare in Idaho with small populations or localized distribution, and currently have low threat levels. However, due to the small populations and habitat area, certain future land uses in close proximity could significantly jeopardize these species. 2 NatureServe Conservation Ranks NatureServe conservation ranks are assessed at both the global and subnational (e.g., state) scales. G = Global rank indicator; denotes rank based on rangewide conservation status. T = Trinomial rank indicator; denotes global conservation status of infraspecific taxa. S = State rank indicator; denotes rank based on conservation status within Idaho. NatureServe Global Conservation Status Ranks GX: Presumed Extinct. GH: Possibly Extinct. G1: Critically Imperiled - at very high risk of extinction due to extreme rarity, very steep declines, or other factors. G2: Imperiled - at high risk of extinction or elimination due to very restricted range, very few populations, steep declines, or other factors. G3: Vulnerable - at moderate risk of extinction due to a restricted range, relatively few populations, recent and widespread declines, or other factors. G4: Apparently Secure - uncommon but not rare, some cause for long-term concern due to declines or other factors. G5: Secure - common, widespread and abundant. G#G#: Range Rank—range rank (e.g., G2G3, G1G3) is used to indicate uncertainty about the conservation status. T#: Infraspecific Taxon (subspecies or varieties) status is indicated by a “T-rank” following the species’ global rank. Rules for assigning T-ranks follow the same principles for global conservation status ranks. For example, the global rank of a critically imperiled subspecies of an otherwise widespread and common species would be G5T1. 3 NatureServe State Conservation Status Ranks SX: Presumed Extirpated. SH: Possibly Extirpated. S1: Critically Imperiled - at very high risk of extirpation in the jurisdiction (state) due to a very restricted range, very few populations or occurrences, very steep declines, severe threats, or other factors. S2: Imperiled - at high risk of extirpation in the jurisdiction (state) due to a restricted range, few populations or occurrences, steep declines, severe threats, or other factors. S3: Vulnerable - at moderate risk of extirpation in the jurisdiction (state) due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors. S4: Apparently Secure - at a fairly low risk of extirpation in the jurisdiction (state) due to an extensive range and/or many populations or occurrences, but with possible cause for some concern as a result of local recent declines, threats, or other factors. S5: Secure - at very low or no risk of extirpation in the jurisdiction (state) due to a very extensive range, abundant populations or occurrences, with little to no concern from declines or threats. S#S#: range rank (e.g. S2S3) used to indicate uncertainty about the conservation status. U.S. Fish and Wildlife Service— Endangered Species Act Status Categories Taxonomy Listed Endangered: Taxa in danger of extinction throughout all or a significant portion of their range. Listed Threatened: Taxa likely to be classified as Endangered within the foreseeable future throughout all or a significant portion of their range. Proposed Endangered: Taxa proposed to be listed as Endangered (formal rulemaking in progress). 4 Proposed Threatened: Taxa proposed to be listed as Threatened (formal rulemaking in progress). Candidate species: Taxa for which the USFWS has on file sufficient information on biological vulnerability and threats to support issuance of a proposed rule to list, but issuance of the proposed rule is precluded. BLM DISTRICT AND FIELD OFFICE SPECIES GUIDE For the species location table on the following page, the field office acronyms are listed as follows: Boise District Office FR = Four Rivers Field Office BP = Morley Nelson Snake River Birds of Prey National Conservation Area BR = Bruneau Field Office OW = Owyhee Field Office Twin Falls District Office JB = Jarbidge Field Office BU = Burley Field Office CR = Craters of the Moon National Monument and Preserve SH = Shoshone Field Office Idaho Falls District Office US = Upper Snake Field Office PO = Pocatello Field Office CH = Challis Field Office SA = Salmon Field Office Coeur d’Alene District Office CD = Couer d’Alene Field Office CW = Cottonwood Field Office 5 BLM DISTRICT AND FIELD OFFICE SPECIES GUIDE SPECIES NAME COMMON NAME Abronia mellifera var. pahoveorum Allium aaseae Astragalus amblytropis Astragalus amnis-amissi Astragalus anserinus Astragalus aquilonius Astragalus asotinensis Astragalus atratus var. inseptus Astragalus packardiae Astragalus sterilis Astragalus jejunus var. jejunus Astragalus mulfordiae Astragalus oniciformis Calamagrostis tweedyi Carex aboriginum Carex idahoa Chaenactis cusickii Eriogonum capistratum var. welshii Howellia aquatilis Lepidium papilliferum Mentzelia mollis Mirabilis macfarlanei Monardella angustifolia Oenothera psammophila Oxytropis besseyi var. salmonensis Phacelia inconspicua Physaria didymocarpa var. lyrata Pinus albicaulis Polemonium elusum Silene spaldingii Spiranthes diluvialis Stanleya confertiflora Thelypodium repandum Trifolium owyheense 6 Boise sand-verbena Aase’s onion Challis milkvetch Lost River milkvetch Goose Creek milkvetch Lemhi milkvetch Asotin milkvetch Camas milkvetch Packard’s milkvetch barren milkvetch starveling milkvetch Mulford’s milkvetch Picabo milkvetch Cascade reedgrass Indian Valley sedge Idaho sedge Cusick’s pincushion Welsh’s buckwheat Water howellia slickspot peppergrass smooth stickleaf Macfarlane’s four-o’clock narrow-leaf monardella Saint Anthony evening primrose Challis crazyweed obscure phacelia Salmon twin bladderpod whitebark pine elusive Jacob’s-ladder Spalding’s catchfly Ute ladies-tresses Malheur princesplume wavy-leaf thelypody Owyhee clover Boise Twin Falls Idaho Falls Coeur d’Alene FR BP BR OW JB BU CR SH US PC CH SA CD CW X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 7 Idaho Location Map: Boise sand-verbena BOUNDARY ia m ron b A BONNER a var. pahoveorum, hea ellifer d-li ke i nfl ore sce nc e ,B b ar ar a KOOTENAI Er t ter SHOSHONE BENEWAH LATAH CLEARWATER NEZ PERCE LEWIS IDAHO LEMHI ADAMS VALLEY WASHINGTON CLARK CUSTER PAYETTE GEM FREMONT BOISE JEFFERSON MADISON BUTTE CANYON CAMAS ADA BONNEVILLE BLAINE ELMORE TETON BINGHAM LINCOLN GOODING MINIDOKA OWYHEE TWIN FALLS 8 CARIBOU POWER JEROME CASSIA BANNOCK BEAR LAKE ONEIDA FRANKLIN BOISE SAND-VERBENA Abronia mellifera Douglas ex Hook. var. pahoveorum Ertter & Nosratinia Nyctaginaceae (Four-o’clock family) Conservation ranks: NatureServe G4T1/T2 S1/S2; BLM Type 2 Description Perennial herb with decumbent to more often ascending stems up to 55 cm long. Well-developed plants form mounds 10+ dm in diameter. Leaves green, flexible, narrowly to broadly elliptic-lance shaped, 1-8 cm long and 0.5-2.5 cm wide. Inflorescence with abundant (sometimes sparse) glandular hairs, consisting of 25-35 mildly fragrant, whitish to pinkish flowers in a showy, head-like arrangement. Flowers with a slender tube 12-25 mm long and an abruptly spreading limb. Bracts subtending the inflorescence usually broadly ovate to nearly round, sometimes narrowly ovate in older plants, usually strongly overlapping, and mostly 10-25 mm long and 8-12 mm wide. Fruits with welldeveloped wings, except the outermost wingless or with only irregular rudimentary wings. The winged fruits more or less with glandular hairs. Field Identification Tips Flowers for Abronia are borne in sessile (stalkless) heads subtended by 4-5 distinct (not fused) involucral bracts. The funnel-shaped flowers abruptly expand to a 5-lobed limb. Mature to near-mature fruits are often required for positive identification of Abronia species because of the variation of vegetative structures within each taxon. Similar Species Differs from other components of the Abronia mellifera complex in the larger inflorescence bracts that are often broadly ovate or even nearly round, and in the combination of lack of rhizomes, relatively narrow, green, flexible leaves, glandular-septate hairs in the inflorescence, and moderately hairy fruit with relatively large wings. Phenology Flowers April to September. 9 Habitat Hills and slopes on sand and lake bed sediment substrates below 1100 m.(3600 ft) elevation. Distribution Endemic to southwestern Idaho on the north side of the western Snake River Plain, extending in sporadic fashion along the lower foothills from Boise to Horseshoe Bend, and west in the sandy ridge complex separating the Boise and Payette river drainages. Taxonomy Boise sand-verbena was described as a new variety in 2016. It is included in the Flora of the Pacific Northwest, second edition published in 2018. However, plants would have keyed and been identified as Abronia fragrans using the earlier, 1973 edition of Flora of the Pacific Nortwest. As currently circumscribed, A. fragrans is absent from the Pacific Northwest. A full analysis and revision of the A. mellifera complex is in preparation. References Ertter, B., and S. Nosratinia. 2016. A new variety of Abronia mellifera (Nyctaginaceae) of conservation concern in southwestern Idaho. Phytoneuron 2016-20: 1–4. Published 3 March 2016. Spellenberg, R. 2012. Abronia. Pages 593–600. In: Intermountain Flora: Vascular Plants of the Intermountain West, U.S.A. Vol.2, Part A. By N.H. Holmgren, P.K. Holmgren, J.L. Reveal, and collaborators. The New York Botanical Garden, Bronx, NY. 10 Abronia mellifera var. pahoveorum, plant (above) and habitat (below), Barbara Ertter 11 Idaho Location Map: Aase’s onion BOUNDARY m Alliu aaseae, plant detail, BONNER Rob er tM ose le y( ID N H P) KOOTENAI SHOSHONE BENEWAH LATAH CLEARWATER NEZ PERCE LEWIS IDAHO LEMHI ADAMS VALLEY WASHINGTON CLARK CUSTER PAYETTE GEM FREMONT BOISE JEFFERSON MADISON BUTTE CANYON CAMAS ADA BONNEVILLE BLAINE ELMORE TETON BINGHAM LINCOLN GOODING MINIDOKA OWYHEE TWIN FALLS 12 CARIBOU POWER JEROME CASSIA BANNOCK BEAR LAKE ONEIDA FRANKLIN AASE’S ONION Allium aaseae Ownbey Amaryllidaceae (Amaryllis family) Conservation ranks: NatureServe G2 S2; BLM Type 2 Description Perennial from an underground bulb. Leaves 2 for each flowering stem, linear, 1-4 mm wide, at least twice as long as the flower stalk, and often arching towards or lying on the ground. The flower stalk only 1-3 cm above ground level, round to slightly flattened, and not winged. Inflorescence a tight umbel of a few to >20 flowers subtended by 2 or 3 bracts. Flowers pink, often vividly so, and consisting of 6 tepals 6-10 mm long, with margins that may or may not have tiny, irregularly distributed teeth. The flowers fade to white and become papery as the fruit matures. Stamens shorter than the tepals, the anthers and pollen yellow. Field Identification Tips The combination of its low stature, relatively long, narrow leaves, deep pink flowers, yellow anthers and pollen, and confinement to coarse sand soils generally below 1130 m (3700 ft) elevation help distinguish Aase’s onion. The leaves remain green during flowering, but tend to lose their color and become deciduous as the fruits mature. Aboveground plant parts break, blow away, and disappear after the seeds mature. Similar Species Several species of Allium occur within the range of Aase’s onion. The one most likely to cause confusion is A. simillimum. It differs by having white tepals with a green or reddish midvein, although some individuals or populations may be flushed with pink; tepal margins that have tiny, regularly distributed teeth when viewed under a hand lens; and anthers that are purple or mottled purple and with white or grayish pollen. Allium brandegeei is another small, low-growing onion. It differs in having whitish tepals with entire margins and shorter leaves mostly less than twice as long as the flowering stem. 13 Phenology Flowering as early as late February into April, depending on elevation and seasonal weather patterns. Middle March is often peak flowering, but this can vary year to year. Habitat Coarse sandy soil on dry, open, gentle to steep slopes, often along upper slopes near ridgelines, most commonly on southerly exposures, but ranging from east to west aspects. Usually associated with open, relatively sparsely vegetated bitterbrush/bunchgrass or bitterbrushsagebrush/bunchgrass communities. Much of this habitat within the range of Aase’s onion has been altered by wildfire and weed invasion. Associated species may include Purshia tridentata, Artemisia tridentata, Aristida purpurea var. longiseta, Pseudoroegneria spicata, Hesperostipa comata, Bromus tectorum, Balsamorhiza sagittata, and Erodium cicutarium. Most populations occur between 820-1310 (2700-4300 ft) elevation, with the majority below 1130 (3700 ft). Distribution Endemic to southwestern Idaho, occurring in the lower foothills from the Boise to Emmett area and also near Weiser in Ada, Boise, Gem, Payette, and Washington counties. Taxonomy No synonyms. Hybridization is suspected between Aase’s onion and A. simillimum in places. References McNeal, D.W. 1993. Taxonomy of Allium aaseae – Allium simillimum in Idaho. Report prepared for Idaho Conservation Data Center, Idaho Department of Fish and Game, Boise, ID. 10 pp. Moseley, R.K., M. Mancuso, and J. Hilty. 1992. Rare plant and riparian vegetation inventory of the Boise Foothills, Ada County, Idaho. Idaho Conservation Data Center, Idaho Department of Fish and Game, Boise, ID. 20 pp. Smith, J.F., and T. Vuong Pham. 1996. Genetic diversity of the narrow endemic Allium aaseae (Alliaceae). American Journal of Botany 83(6):717-726. 14 Allium aaseae, plant habitat, Michael Mancuso 15 Idaho Location Map: Challis milkvetch alus amblytropis, fl Astrag owe r de BOUNDARY tail , Je ssi ca Ir n wi BONNER KOOTENAI SHOSHONE BENEWAH LATAH CLEARWATER NEZ PERCE LEWIS IDAHO LEMHI ADAMS VALLEY WASHINGTON CLARK CUSTER PAYETTE GEM FREMONT BOISE JEFFERSON MADISON BUTTE CANYON CAMAS ADA BONNEVILLE BLAINE ELMORE TETON BINGHAM LINCOLN GOODING MINIDOKA OWYHEE TWIN FALLS 16 CARIBOU POWER JEROME CASSIA BANNOCK BEAR LAKE ONEIDA FRANKLIN CHALLIS MILKVETCH Astragalus amblytropis Barneby Fabaceae (Pea or Legume family) Conservation ranks: NatureServe G3 S3; BLM Type 3 Description Low herbaceous perennial with stems 10-30 cm long, often prostrate, and with a divaricate branching pattern. Leaves pinnately compound, divided into 7-13 oblong-ovate leaflets, each 5-10 mm long and usually with a small notch at the tip. Leaves have a grayish cast due to a dense covering of minute, appressed hairs. Flowers pea-like, pale yellow to cream, often tinged with purple, 6-8 mm long. Fruit pods inflated, membranous, 2-celled, up to 4 cm long, not red-mottled, but with numerous minute appressed hairs. Field Identification Tips The divaricately branching stems, neat silvery-gray leaves, small flowers with petals of nearly equal length, and, bladdery, 2-celled pods distinguish this species. The pods are initially pale green suffused with purple, then become straw-colored and somewhat lustrous when ripe, and seem oversized in proportion to the leaves and flowers. Similar Species Multiple species of Astragalus occur within the range of Challis milkvetch, with most being readily distinguished from Challis milkvetch by some combination of a taller more upright habit, larger or different color flowers, or much different fruit pods. Challis milkvetch may be confused with A. aquilonius because of their similar habit and greatly swollen fruit pod. Astragalus aquilonius differs by having greenish-white flowers and a one-chambered pod that is hairless or minutely pubescent with soft hairs. Astragalus platytropis and A. whitneyi are two other low-growing milkvetches with inflated fruit pods found in east-central Idaho. However, the pods are red- to purple-mottled for both species. Phenology Flowering begins as early as mid-May and may extend into early August. Fruit pods may be found from late May into early September. 17 Habitat Usually associated with salt desert shrub or Wyoming big sagebrush communities; often on relatively unstable volcanic ash, talus, or shaley substrate that have low vegetation cover. Sites are often steep, with southerly to west aspects being most common. Associated species may include Atriplex confertifolia, Artemisia tridentata spp. wyomingensis, Leymus salina spp. salmonis, Pseudoroegneria spicata, Cryptantha spiculifera, Penstemon eriantherus, Phacelia glandulosa, Chaenactis douglassii, and Hymenopappus filifolius var. idahoensis. Distribution Endemic to east-central Idaho in Custer and Lemhi counties, centered along the Salmon River Canyon and its tributaries from the Clayton area northward. Populations are also known from sites south of Challis on the west slope of the Pahsimeroi Mountains. Elevations at known populations range from approximately 1400-2200 m (4600-7220 ft), with most located between 1675-1980 m (5500 - 6500 ft). Taxonomy No synonyms. References Rittenhouse, B. and R. Rosentreter. 1994. The autecology of Challis milkvetch, and endemic of east-central Idaho. Natural Areas Journal 14 (1):22-30. Moseley, R.K. 1989. Field investigations of four astragali, all Region 4 sensitive species, on the Salmon National Forest, with notes on two others. Idaho Natural Heritage Program, Idaho Department of Fish and Game, Boise, ID. 19 pp plus appendices. 18 Allium amblytropis, fruits and foliage (above) and sprawling habit (below), Jessica Irwin 19 Idaho Location Map: Lost River milkvetch galus amnis-amissi, flowe rs, L Astra yn n BOUNDARY Kin ter ( ID N BONNER ) HP KOOTENAI SHOSHONE BENEWAH LATAH CLEARWATER NEZ PERCE LEWIS IDAHO LEMHI ADAMS VALLEY WASHINGTON CLARK CUSTER PAYETTE GEM FREMONT BOISE JEFFERSON MADISON BUTTE CANYON CAMAS ADA BONNEVILLE BLAINE ELMORE TETON BINGHAM LINCOLN GOODING MINIDOKA OWYHEE TWIN FALLS 20 CARIBOU POWER JEROME CASSIA BANNOCK BEAR LAKE ONEIDA FRANKLIN LOST RIVER MILKVETCH Astragalus amnis-amissi Barneby Fabaceae (Pea; Legume family) Conservation ranks: NatureServe G3 S3; BLM Type 3 Description Slender, weakly ascending, thinly pubescent, perennial forb up to 25 cm tall. Leaves pinnately compound with 7-13 leaflets, each 3-15 mm long, elliptic to broadly egg-shaped, thin-textured, medium to dark semiglossy green, and usually tipped with an apical notch. Inflorescence a loose raceme of spreading, pea-like white flowers faintly marked with purple and about 10 mm long. Calyx 4-6 mm long with black, or in part white, short appressed hairs. Fruit pods sessile, moderately inflated, about 15-17 mm long, green or purplish, and with short appressed hairs. Field Identification Tips Distinguished by its slender, weakly ascending habit, semi-glossy, relatively dark green, apically notched leaflets, small whitish flowers faintly marked with purple, moderately inflated pods, and limestone cliff and associated talus habitat. Similar Species Astragalus amblytropis differs in its more divaricately branched habit, thicker-textured, silvery leaflets, slightly smaller, dull yellowish flowers, and larger, more inflated fruit pods. Astragalus alpinus superficially resembles Lost River milkvetch, but has a slender, subterranean, adventitious root system, and narrower, pendulous, stipitate fruit pods. Phenology Flowering begins in early to mid-June and continues into July. Habitat Ledges, crevices, and outcrops on steep limestone cliffs, and talus along cliff bases; often in partial shade. Populations known from approximately 1675-2440 m (5500-8000 ft) elevation, with most between 1950-2195 m (6400-7200 ft). Associated species may include Cercocarpus ledifolius, Petrophytum caespitosum, Draba oreibata, Erigeron caespitosus, Leymus cinereus, and Pseudotsuga menziesii. 21 Distribution Endemic to Custer and Butte counties in east-central Idaho, on the eastern and western slopes of the southern half of the Lost River Range, the lower slopes of Hawley Mountain, and the southern end of the Lemhi Range. Taxonomy No synonyms. References Hitchcock, C.L. 1961. Astragalus amnis-amissi Barneby. Pages 219-221 In: Vascular Plants of the Pacific Northwest, Part 3: Saxifragaceae to Ericaceae, By C.L. Hitchcock, A. Cronquist, M. Ownbey, J.W. Thompson. University of Washington Press, Seattle, WA.. Moseley, R.K. 1989. Field investigations of four astragali, all Region 4 sensitive species, on the Salmon National Forest, with notes on two others. Idaho Natural Heritage Program, Idaho Department of Fish and Game, Boise, ID. 19 pp plus appendices. Astragalus amnis-amissi, habit with glossy leaves, Anne Halford (BLM) 22 Astragalus amnis-amissi, Fruits and foliage (above) and habitat (below), Lynn Kinter (IDNHP) 23 Idaho Location Map: Goose Creek milkvetch us anserinus, f l owe Astragal rs a nd fru i BOUNDARY t, I DN P H BONNER KOOTENAI SHOSHONE BENEWAH LATAH CLEARWATER NEZ PERCE LEWIS IDAHO LEMHI ADAMS VALLEY WASHINGTON CLARK CUSTER PAYETTE GEM FREMONT BOISE JEFFERSON MADISON BUTTE CANYON CAMAS ADA BONNEVILLE BLAINE ELMORE TETON BINGHAM LINCOLN GOODING MINIDOKA OWYHEE TWIN FALLS 24 CARIBOU POWER JEROME CASSIA BANNOCK BEAR LAKE ONEIDA FRANKLIN GOOSE CREEK MILKVETCH Astragalus anserinus Atwood, Goodrich & Welsh Fabaceae (Pea, Legume family) Conservation ranks: NatureServe G2 S1; BLM Type 2 Description Low perennial herb from a slender taproot that forms compact mats up to approximately 15 cm diameter. Herbage with dense, soft, bent to tangled hairs that gives the plant a grayish-green color. Leaves small, pinnately compound with 5-15 leaflets, each 3-6 mm long. Inflorescence a few-flowered raceme not elevated above the plant. Calyx 5-7 mm long with white hairs. Petals pink-purplish, the banner 9-11 mm long. Fruit pods reddish-brown, 9-12 mm long with a prominent beak and typically lying on the ground near or under the edge of the low-spreading stems. Thin hairs of the pods do not conceal the surface of the fruit. Field Identification Tips Distinguished by its low, tufted habit, densely hairy foliage, small leaves, small flowers, and beaked, reddish-brown pods with hairs not so dense as to conceal the fruit surface. Similar Species Most likely to be confused with varieties of Astragalus purshii, a species that usually has larger leaflets (2-14 mm long), flowers (9-25 mm long), and calyx (6-16 mm long); plus fruits with dense silky hairs that conceal the pod’s surface. Flower color is variable for Pursh’s milkvetch, ranging from whitish, to pale yellowish, to pink-purple. Two other similar-looking species are A. newberryi and A. calycosus. Astragalus newberryi differs from Goose Creek milkvetch by its larger leaflets (5-16 mm long), flowers (17-32 mm long), and calyx (9-20 mm long); plus fruits with dense silky hairs that conceal the pod’s surface. Astragalus calycosus has mostly appressed, straight, silvery hairs, usually larger leaflets (2-19 mm long), and usually larger flowers (10-15 mm long) that range from whitish to purple. Hairs on the 2-chambered pods do not conceal the fruit surface. Clear differences in habit, size, and features of the leaves, flowers, or fruits, readily distinguish other species of Astragalus that occur within the range of Goose Creek milkvetch. 25 Phenology Flowering occurs from middle or late May into most of June. Fruit set begins in early June, and pods can remain on the plants for several months. Astragalus anserinus, plant, Michael Mancuso Habitat Open, dry, relatively sparsely vegetated outcrops of silty to sandy soils weathered from tuffaceous rocks of the Salt Lake Formation. Soils are usually a light gray and often have abundant gravels and/or rocks at the surface. Plants may also occupy sandy loam and gravelly sandy loam soils surrounding these tuffaceous outcrops. Sites vary from flat to steep, and can include all aspects, although plants are uncommon on northerly-facing exposures. Goose Creek milkvetch occurs within or adjacent to Juniperus osteosperma or Artemisia tridentata ssp. wyomingensis plant communities. Other commonly associated species include Chrysothamnus viscidiflorus, Hesperostipa comata, Achnatherum hymenoides, Poa secunda, Chaenactis douglasii, Cryptantha humilis, Eriogonum ovalifolium, and Ipomopsis congesta. Elevations at known occurrences range from approximately 1495-1790 m (4900-5885 ft). 26 Distribution Goose Creek milkvetch is largely endemic to the Goose Creek drainage in Cassia County, Idaho; Elko County, Nevada; and Box Elder County, Utah. At least one population is located a short distance outside the watershed. Taxonomy No synonyms. References Barneby, R.C. 1989. Astragalus. Pages 39-176 In: Intermountain Flora. Vascular Plants of the Intermountain West, U.S.A. Vol. 3 Part B, by A. Cronquist, A.H. Holmgren, N.H. Holmgren, J.L. Reveal, P.K. Holmgren. The New York Botanical Garden, Bronx, NY. Mancuso, M., and R.K. Moseley. 1991. Report on the conservation status of Astragalus anserinus, in Idaho and Utah. Idaho Conservation Data Center, Idaho Department of Fish and Game, Boise, ID. 32 pp plus appendices. Astragalus anserinus, habitat, Michael Mancuso 27 Nevada Natural Heritage Program. 2001. Nevada rare plant atlas. Compiled by the Nevada Natural Heritage Program and edited by James D. Morefield. Available on-line: http://heritage.nv.gov/atlas U.S. Department of Interior. 2015. Conservation Agreement and Strategy for Goose Creek milkvetch (Astragalus anserinus). Prepared for Bur