Index of Species Information

SPECIES:  Wyethia amplexicaulis
Photo by Mary Ellen Harte,



SPECIES: Wyethia amplexicaulis
AUTHORSHIP AND CITATION : Matthews, Robin F. 1993. Wyethia amplexicaulis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: []. Revisions : Photos added on 17 December 2014. ABBREVIATION : WYEAMP SYNONYMS : NO-ENTRY SCS PLANT CODE : WYAM COMMON NAMES : mule-ears mules ears wyethia mule ear dock black sunflower TAXONOMY : The currently accepted scientific name of mule-ears is Wyethia amplexicaulis (Nutt.) Nutt. It is in the family Asteraceae [12,32]. Mule-ears apparently hybridizes with W. arizonica Gray [12] and with arrowleaf balsamroot (Balsamorhiza sagittata) [35]. LIFE FORM : Forb FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


SPECIES: Wyethia amplexicaulis
GENERAL DISTRIBUTION : Mule-ears is distributed from Washington to Montana and south to Colorado and Nevada [12,16,32]. ECOSYSTEMS : FRES20 Douglas-fir FRES21 Ponderosa pine FRES23 Fir - spruce FRES28 Western hardwoods FRES29 Sagebrush FRES34 Chaparral - mountain shrub FRES35 Pinyon - juniper FRES36 Mountain grasslands FRES37 Mountain meadows STATES : CO ID MT NV OR UT WA WY BLM PHYSIOGRAPHIC REGIONS : 5 Columbia Plateau 6 Upper Basin and Range 7 Lower Basin and Range 8 Northern Rocky Mountains 9 Middle Rocky Mountains 10 Wyoming Basin 11 Southern Rocky Mountains 12 Colorado Plateau 13 Rocky Mountain Piedmont KUCHLER PLANT ASSOCIATIONS : K010 Ponderosa shrub forest K011 Western ponderosa forest K012 Douglas-fir forest K015 Western spruce - fir forest K018 Pine - Douglas-fir forest K020 Spruce - fir - Douglas-fir forest K021 Southwestern spruce - fir forest K023 Juniper - pinyon woodland K024 Juniper steppe woodland K037 Mountain-mahogany - oak scrub K038 Great Basin sagebrush K050 Fescue - wheatgrass K051 Wheatgrass - bluegrass K055 Sagebrush steppe K056 Wheatgrass - needlegrass shrubsteppe K063 Foothills prairie SAF COVER TYPES : 206 Engelmann spruce - subalpine fir 210 Interior Douglas-fir 217 Aspen 220 Rocky Mountain juniper 237 Interior ponderosa pine 238 Western juniper 239 Pinyon - juniper SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Mule-ears has a wide ecological amplitude, occurring in many plant communities. It is most abundant in mesic sagebrush (Artemisia spp.)-grassland habitats. It is also common in woodlands and seral coniferous forests above the elevational limits of sagebrush [28,35].
A ponderosa pine/mule-ears savanna in Malheur NF, OR. Photo by Dave Powell, USDA Forest Service,
Trembling aspen (Populus tremuloides)/mule-ears community types in the
Intermountain region are minor and mostly confined to the north [17].
In the Bridger-Teton, Caribou, and Targhee National Forests, these types
usually result from severe overgrazing.  These communities generally
have an open canopy of trembling aspen with the herbaceous layer
completely dominated by mule-ears [18,37].  Other species sometimes
cooccurring include mountain snowberry (Symphoricarpos oreophilus),
Saskatoon serviceberry (Amelanchier alnifolia), western stickseed
(Hackelia floribunda), common dandelion (Taraxacum officinale), western
coneflower (Rudbeckia occidentalis), cinquefoil (Potentilla spp.),
lupine (Lupinus spp.), butterweed groundsel (Senecio serra), California
brome (Bromus carinatus), slender wheatgrass (Elymus trachycaulus), blue
wildrye (E.  glaucus), and Kentucky bluegrass (Poa pratense) [17,18,37].
Trembling aspen/mule-ears community types in the Intermountain region
are fairly stable [17,18,36].  Mueggler and Campbell [18] suggested that
they should be recognized as distinct habitat types on the Caribou and
Targhee National Forests.

Other species commonly associated with mule-ears include ninebark
(Physocarpus malvaceus), Oregon-grape (Mahonia repens), Gambel oak
(Quercus gambelii), Wood's rose (Rosa woodsii), antelope bitterbrush
(Purshia tridentata), rubber rabbitbrush (Chrysothamnus nauseosus), low
rabbitbrush (C. viscidiflorus), curlleaf mountain-mahogany (Cercocarpus
ledifolius), Rocky Mountain maple (Acer glabrum), arrowleaf balsamroot,
western yarrow (Achillea millefolium), slenderleaf collomia (Collomia
linearis), duncecap larkspur (Delphinium occidentale), buckwheat
(Eriogonum spp.), sticky geranium (Geranium viscosissimum), bluebunch
wheatgrass (Pseudoroegneria spicata), Idaho fescue (Festuca idahoensis),
cheatgrass (Bromus tectorum), prairie junegrass (Koeleria cristata), and
bluegrass (Poa spp.) [2,3,11,14].

Publications listing mule-ears as a dominant herbaceous-layer species
are as follows:

Subalpine forb community types of the Bridger-Teton National Forest,
  Wyoming [11]
Aspen community types on the Caribou and Targhee National Forests in
  southeastern Idaho [18]
Aspen community types of the Intermountain Region [17]
The vegetation of the Wasatch Mountains, Utah and Idaho [22]
Aspen community type classifications in the Intermountain West [36]
Aspen community types on the Bridger-Teton National Forest in western
  Wyoming [37].


SPECIES: Wyethia amplexicaulis
IMPORTANCE TO LIVESTOCK AND WILDLIFE : Mule deer prefer mule-ears early in the growing season [5,19,24]. Sheep forage new leaves in spring and early summer. Mature foliage is coarse and harsh, and plants dry out by mid-summer, so it is little used after early summer. Elk, deer, and all classes of livestock eat the flower heads [26,28,35]. PALATABILITY : Mule-ears is generally unpalatable [1,8,19,37]. However, the leaves may be moderately palatable in the spring, and flower heads are relished by livestock, deer, and elk [11,28]. NUTRITIONAL VALUE : Mule-ears is generally poor in energy and protein value [8]. July estimates for crude protein and in-vitro dry matter digestiblity for mule-ears collected in a moist meadow were 11.1 percent and 75.7 percent, respectively [27]. COVER VALUE : Mule-ears often forms dense stands [22,28,30,37] and may provide good cover for birds and small mammals [8]. Blue grouse nests in Utah are commonly located in sagebrush-mule-ears vegetation near trees or tall shrubs [23]. VALUE FOR REHABILITATION OF DISTURBED SITES : In the Wasatch Mountains of Utah and Idaho, mule-ears forms dense cover and its well-developed root system aids in preventing erosion [22]. Mule-ears may be useful in revegetating mine spoils [35]. OTHER USES AND VALUES : Native Americans fermented the roots of mule-ears for 2 days in a pit heated with hot stones to make a sweet flavored food [26,28]. OTHER MANAGEMENT CONSIDERATIONS : Mule-ears-dominated understory communities in the Intermountain region have relatively high production levels, but the production is mainly from unpalatable mule-ears [11,17]. These stands are poor livestock range and poor wildlife habitat because of a lack of structural and species diversity [17]. The understory of many trembling aspen/mule-ears stands has been altered due to severe grazing pressure, as evidenced by the overwhelming dominance of mule-ears in environments that could support palatable grasses and forbs [17]. When grazing pressure is less intense and a shrub layer is present, such as in trembling aspen/mountain snowberry-mule-ears community types, ground-level shading may be too intense to support a dominant cover of mule-ears [17]. Mule-ears dominates some mountain meadows in northeastern Oregon that are in poor condition due to grazing. It is less abundant in meadows that have been improved by seeding with desirable forage [27]. Mule-ears has a negative effect on available soil moisture because it uses large amounts of moisture early in the season [19,37]. If grazing was restricted, mule-ears would probably still dominate many sites to the exclusion of other plants because of this factor [37]. Triclopyr or 2,4-D applied early in the blooming period effectively controls mule-ears [20,30,33].


SPECIES: Wyethia amplexicaulis
GENERAL BOTANICAL CHARACTERISTICS : Mule-ears is a native, perennial, cool-season forb with stems up to 32 inches (80 cm) tall. The leaves are alternate and are 8 to 16 inches (20-40 cm) long and 2 to 6 inches (5-15 cm) wide. There are usually several flower heads but flower heads may occasionally be solitary. The fruits are achenes [12,16,32]. Mule-ears has a stout taproot up to 9 inches (22 cm) in circumference. The taproot may reach depths of over 6 feet (180 cm). Strong lateral roots run 3 to 4 feet (90-120 cm) from the main root [31]. Mule-ears is strongly aromatic [1,19]. RAUNKIAER LIFE FORM : Hemicryptophyte Geophyte REGENERATION PROCESSES : Mule-ears reproduces by seed [19,26,30,35]. Seeds germinate without stratification, but a cool-moist stratification greatly enhances germination. Best germination occurs when seeds are stratified for 4 weeks at 35 to 41 degrees Fahrenheit (2-5 deg C) [35]. Mule-ears sprouts from underground rootstalks or from the root crown following damage to aboveground portions of the plant [20,37]. SITE CHARACTERISTICS : Mule-ears is found in moist draws, meadows, open woods, and open grasslands [12,13,19,26]. Elevational limits of mule-ears are from 4,500 to 11,000 feet (1,360-3,300 m) [8]. Mule-ears requires 10 to 18 inches (25.4-45.7 cm) of annual precipitation [19]. It grows well on sandy loam, loam, and clay-loam textured soils [8], but is apparently most aggressive in heavy clay soils [11,18]. Mule-ears grows well on gentle to moderately steep slopes [8]. The trembling aspen/mule-ears community types of the Bridger-Teton, Caribou, and Targhee National Forests are usually found below 7,000 feet (2,120 m). They most often occur in heavy clay soils with slopes seldom exceeding 25 percent [17,18,37]. Mule-ears-dominated subalpine forb communities also occur in heavy clay soils on the Bridger-Teton National Forest. The forb communities are characterized by large stands of mule-ears surrounded by trembling aspen or subalpine fir (Abies lasiocarpa). They are found at the lower elevations of the subalpine zone (average elevation 7,296 feet [2,210 m]). Average soil pH of these stands is 6.4 [11]. SUCCESSIONAL STATUS : Mule-ears is highly competitive and aggressive and often occurs in large, dense, almost pure stands [26,28,30]. Its aggression on some sites may be partly attributed to its ability to dominate heavy clay soils [28] and its tendency to monopolize soil moisture [19,37]. It excludes other species in some heavily grazed areas [11,17,35]. Even when grazing pressure is eliminated, mule-ears persists for a long time [22]. Mule-ears is common in seral coniferous forests within its range [35]. SEASONAL DEVELOPMENT : Mule-ears begins growth in March or April and flowers from April until June [26]. Annual growth usually dries up by July [31].


SPECIES: Wyethia amplexicaulis
FIRE ECOLOGY OR ADAPTATIONS : Mule-ears probably sprouts after fire damage. Postfire sprouting has not been documented, but sprouting was noted following top-kill by disking on the Targhee National Forest. Mule-ears apparently sprouted from damaged roots [37]. Mule-ears is covered with a varnish-like resin [16] that may make it fairly flammable when cured. POSTFIRE REGENERATION STRATEGY : Geophyte, growing points deep in soil


SPECIES: Wyethia amplexicaulis
IMMEDIATE FIRE EFFECT ON PLANT : Information on the effect of fire on mule-ears is not available in the literature. Moderately severe or severe fires probably at least top-kill mule-ears. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Young and Evans [34] reported that mule-ears density generally increases after rangeland fires. Postfire frequencies (percent) for mule-ears in seral big sagebrush (Artemisia tridentata)/Thurber needlegrass (Stipa thurberiana) communities after three summer wildfires in Nevada follow: Postfire Year Location 1 2 3 4 __________________________________________________________ Red Rock 3 2 2 4 Hallelujah Junction 2 1 T --- Seven Lakes 2 2 --- --- At the Red Rock site, mule-ears was present within 1 month following the fire. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Predictions of fire behavior and suggested guidelines for management with prescribed fire have been formulated for trembling aspen/mule-ears community types in southeastern Idaho and western Wyoming. It has been suggested that fires in these communities are likely to be of low intensity and will usually spread slowly. Fuel loadings are marginal for sustained spread. Fires may occasionally crown but prescribed fires could be easily controlled in trembling aspen/mule-ears communities [7]. Brown [6] determined that the moisture content of mule-ears in trembling aspen stands is approximately 300 percent when green, but may be as low as 25 percent when cured.


SPECIES: Wyethia amplexicaulis
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Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434] 5. Bodurtha, Timothy S.; Peek, James P.; Lauer, Jerry L. 1989. Mule deer habitat use related to succession in a bunchgrass community. Journal of Wildlife Management. 53(2): 314-319. [6677] 6. Brown, James K. 1985. Fire effects and application of prescribed fire in aspen. In: Sanders, Ken; Durham, Jack; [and others], eds. Rangeland fire effects: Proceedings of a symposium; 1984 November 27-29; Boise, ID. Boise, ID: U.S. Department of the Interior, Bureau of Land Management, Idaho State Office: 38-47. [3658] 7. Brown, James K.; Simmerman, Dennis G. 1986. Appraising fuels and flammability in western aspen: a prescribed fire guide. Gen. Tech. Rep. INT-205. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 48 p. [544] 8. Dittberner, Phillip L.; Olson, Michael R. 1983. The plant information network (PIN) data base: Colorado, Montana, North Dakota, Utah, and Wyoming. 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Aspen community types on the Caribou and Targhee National Forests in southeastern Idaho. Res. Pap. INT-294. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 32 p. [1713] 19. Parker, Karl G. 1975. Some important Utah range plants. Extension Service Bulletin EC-383. Logan, UT: Utah State University. 174 p. [9878] 20. Plummer, A. Perry; Hull, A. C., Jr.; Stewart, George; Robertson, Joseph H. 1955. Seeding rangelands in Utah, Nevada, southern Idaho and western Wyoming. Agric. Handb. 71. Washington, DC: U.S. Department of Agriculture, Forest Service. 73 p. [11736] 21. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843] 22. Ream, Robert Ray. 1964. The vegetation of the Wasatch Mountains, Utah and Idaho. Madison, WI: University of Wisconsin. 178 p. Ph.D. thesis. [5506] 23. Schroeder, Richard L. 1984. Habitat suitability index models: blue grouse. FWS/OBS-82/10.81. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 19 p. [11718] 24. Smith, Arthur D. 1953. Consumption of native forage species by captive mule deer during summer. Journal of Range Management. 6: 30-37. [2161] 25. Stickney, Peter F. 1989. Seral origin of species originating in northern Rocky Mountain forests. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT; RWU 4403 files. 7 p. [20090] 26. Stubbendieck, J.; Hatch, Stephan L.; Hirsch, Kathie J. 1986. North American range plants. 3rd ed. Lincoln, NE: University of Nebraska Press. 465 p. [2270] 27. Svejcar, Tony; Vavra, Martin. 1985. Seasonal forage production and quality on four native and improved plant communities in eastern Oregon. Technical Bulletin 149. Corvallis, OR: Oregon State University, Agricultural Experiment Station. 24 p. [2298] 28. U.S. Department of Agriculture, Forest Service. 1937. Range plant handbook. Washington, DC. 532 p. [2387] 29. U.S. Department of Agriculture, Soil Conservation Service. 1982. National list of scientific plant names. Vol. 1. List of plant names. SCS-TP-159. Washington, DC. 416 p. [11573] 30. U.S. Department of Agriculture, U.S. Department of the Interior; Range Seeding Equipment Committee. 1959. Handbook: Chemical control of range weeds. Washington, DC: [Publisher unknown]. 93 p. [12129] 31. Weaver, John Ernst. 1915. A study of the root-systems of prairie plants of southeastern Washington. Plant World. 18(9): 227-248, 273-292. [3758] 32. Welsh, Stanley L.; Atwood, N. Duane; Goodrich, Sherel; Higgins, Larry C., eds. 1987. A Utah flora. Great Basin Naturalist Memoir No. 9. Provo, UT: Brigham Young University. 894 p. [2944] 33. Williams, M. Coburn; Ralphs, Michael H. 1987. Effect of herbicides on miserotoxin concentration in Wasatch milkvetch (Astragalus miser var. oblongifolius). Weed Science. 35: 746-748. [3006] 34. Young, James A.; Evans, Raymond A. 1978. Population dynamics after wildfires in sagebrush grasslands. Journal of Range Management. 31(4): 283-289. [2657] 35. Young, James A.; Evans, Raymond A. 1979. Arrowleaf balsamroot and mules ear seed germination. Journal of Range Management. 32(1): 71-74. [2658] 36. Youngblood, Andrew P. 1981. Aspen community type classifications in the Intermountain West. In: DeByle, Norbert V., ed. Symposium proceedings--situation management of two Intermountain species: aspen and coyotes. Volume 1. Aspen; 1981 April 23-24; Logan, UT. Logan, UT: Utah State University, College of Natural Resources: 40-57. [10437] 37. Mueggler, Walter F.; Blaisdell, James P. 1951. Replacing wyethia with desirable forage species. Journal of Range Management. 4(3): 143-150. [22169]

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