Index of Species Information
SPECIES: Rumex acetosella
SPECIES: Rumex acetosella
AUTHORSHIP AND CITATION:
Esser, Lora L. 1995. Rumex acetosella. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
On 5 June 2018, the common name of this species was changed in FEIS
from: sheep sorrel
to: common sheep sorrel. Images were also added.
Acetosella vulgaris Fourr.
NRCS PLANT CODE:
common sheep sorrel
The scientific name of common sheep sorrel is Rumex acetosella L.
[29,34,51,95]. It is in the family Polygonaceae. There are no
recognized infrataxa [34,44].
FEDERAL LEGAL STATUS:
No special status
DISTRIBUTION AND OCCURRENCE
SPECIES: Rumex acetosella
Common sheep sorrel is a forb of Eurasian origin that has naturalized
throughout much of temperate North America [46,75,95].
|Distribution of common sheep sorrel. Map courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [2018, June 5] .
Common sheep sorrel is found in most FRES ecosystems.
AK AZ AR CA CO CT DE FL GA HI
ID IL IN IA KS KY ME MD MA MI
MN MO MT NE NV NH NJ NM NY NC
ND OH OK OR PA RI SC SD TN TX
UT VT VA WA WV WI WY AB BC MB
NB NS ON PQ SK
BLM PHYSIOGRAPHIC REGIONS:
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper 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
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
KUCHLER PLANT ASSOCIATIONS:
SAF COVER TYPES:
Common sheep sorrel is found in most SAF Cover Types.
SRM (RANGELAND) COVER TYPES:
101 Bluebunch wheatgrass
102 Idaho fescue
103 Green fescue
108 Alpine Idaho fescue
110 Ponderosa pine-grassland
201 Blue oak woodland
203 Riparian woodland
204 North coastal shrub
215 Valley grassland
216 Montane meadows
304 Idaho fescue-bluebunch wheatgrass
409 Tall forb
411 Aspen woodland
601 Bluestem prairie
804 Tall fescue
809 Mixed hardwood and pine
HABITAT TYPES AND PLANT COMMUNITIES:
Common sheep sorrel occurs mainly in grassland, mixed-grass prairie, and
montane meadow communities of western North America, but is also common
in forested communities throughout temperate North America.
Common sheep sorrel is common in floodplain and riparian habitats. In western
Washington common sheep sorrel is found on gravel bars and floodplains
dominated by Scouler willow (Salix scouleriana). Other associates
include Virginia strawberry (Fragaria virginiana), velvetgrass (Holcus
lanatus), white clover (Trifolium repens), curly dock (Rumex crispus),
and bog rush (Juncus effusus) . In Oregon common sheep sorrel occurs in a
riparian mountain meadow community dominated by cheatgrass (Bromus
tectorum) . In California common sheep sorrel occurs in a freshwater marsh
community dominated by tall fescue (Festuca arundinacea), sedge (Carex
spp.), and narrow-leaved cattail (Typha angustifolia) .
Common sheep sorrel is commonly found in old fields, annual grassland, and
montane meadow communities. In Connecticut common sheep sorrel occurs in a
postagricultural little bluestem (Schizachyrium scoparium) grassland.
Associates include redtop (Agrostis alba) and yellow sedge (Carex
pensylvanica) . In New Jersey common sheep sorrel is a member of an
old-field plant community dominated by Canada goldenrod (Solidago
canadensis) . Common sheep sorrel is commonly found in southern Appalachian
grassy bald communities dominated by mountain oatgrass (Danthonia
compressa). Other associates include thornless blackberry (Rubus
canadensis), hillside blueberry (Vaccinium pallidum), and violet (Viola
spp.) [56,60]. In Indiana common sheep sorrel occurs in a little bluestem
community with hackberry (Celtis occidentalis) and smooth horsetail
(Equisetum laevigatum) . In Montana common sheep sorrel occurs in
mixed-grass prairie communities .
In California common sheep sorrel is common in annual grassland, montane
meadow, and perennial bunchgrass communities. Associates include ripgut
brome (Bromus rigidus), soft chess (B. hordeaceus), silver hairgrass
(Aira caryophyllea), Kentucky bluegrass (Poa pratense), Sandberg
bluegrass (P. nevadensis), Italian thistle (Carduus pycnocephalus), wild
oat (Avena fatua), and Italian ryegrass (Lolium multiflorum)
At Point Reyes National Seashore, California, common sheep sorrel occurs in a
coastal grassland community with coast rock cress (Arabis
blepharophylla), poison-oak (Toxicodendron diversiloba), California
barberry (Berberis pinnata), and the endangered Sonoma spineflower
(Chorizanthe valida) [11,12].
Common sheep sorrel is a common understory species in forested habitats
throughout North America. In Pennsylvania common sheep sorrel occurs in
eastern white pine (Pinus strobus)-poverty oatgrass (D. spicata)
communities; associates include Canada goldenrod, fireweed (Epilobium
angustifolium), whorled yellow loosestrife (Lysimachia quadrifolia),
Virginia springbeauty (Claytonia virginica), trout lily (Erythronium
americanum), mountain wood sorrel (Oxalis montana), and violet
[3,49,93]. In Alberta common sheep sorrel is a member of an 80-year-old white
spruce (Picea glauca)-jack pine (Pinus banksiana)-feathermoss
(Pleurozium spp.) community . In Idaho common sheep sorrel occurs in
grand fir (Abies grandis)/wild ginger (Asarum caudatum), grand
fir/pachistima (Pachistima myrsinites), and grand fir/ninebark
(Physocarpus malvaceus) habitat types [30,53,54,99]. In California
common sheep sorrel occurs in redwood (Sequoia sempervirens), Douglas-fir
(Pseudotsuga menziesii), and Oregon white oak (Quercus garryana)
In Montana and Wyoming, common sheep sorrel is found in alpine tundra
SPECIES: Rumex acetosella
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
In Arizona common sheep sorrel is grazed by cattle and sheep, but has little
forage value . Common sheep sorrel contains oxalic acid which can be
In California and Ohio common sheep sorrel is grazed by mule deer [50,70]. In
Idaho, Montana, and Wisconsin sharp-tailed grouse and ruffed grouse eat
common sheep sorrel seed [40,41,76,86].
In Utah palatability ratings for common sheep sorrel are fair for cattle and
poor for sheep and horses .
Common sheep sorrel nutritional levels are adequate to meet the requirements of
mule deer . Energy and protein content ratings of common sheep sorrel are
poor. Nutritional values are rated as poor for waterfowl and fair for
elk, mule deer, upland game birds, small nongame birds, and small
In Utah common sheep sorrel cover values are rated as fair for small mammals
and small nongame birds and poor for upland game birds and waterfowl
VALUE FOR REHABILITATION OF DISTURBED SITES:
Common sheep sorrel colonizes disturbed sites such as clearcuts, streambanks,
and surface mined lands. It has been used for revegetation of disturbed
lands, although it is rated low for erosion control, and short- and
long-term revegetation potential . In a mining and smelting region
of Sudbury, Ontario, common sheep sorrel established when a thin sprinkling
of limestone was applied to the soil .
In east-central Texas revegetation of eight unreclaimed mine sites
occurred naturally. These sites and an adjacent unmined site were
sampled to determine vegetational changes over time. The percent
frequency of common sheep sorrel was as follows :
3m* 6m 5y 10y 15y 20y 30y 50y control
0 11 4 6 4 3 0 0 0
*m=months since first sampling, y=years since first sampling
In Pennsylvania an attempt was made to transplant rootstocks of sheep
sorrel on black waste sites created by anthracite mining. All emergent
vegetation was subsequently heat killed .
OTHER USES AND VALUES:
Common sheep sorrel leaves are used in salads [4,51]. The Nuxalk Indians of
British Columbia eat common sheep sorrel .
OTHER MANAGEMENT CONSIDERATIONS:
Common sheep sorrel is classified as a noxious weed in 23 states . It is a
serious weed in pastures and rangelands. Control is difficult because
of its perennial, creeping rhizomes [4,52]. Common sheep sorrel is a common
weed in West Virginia, except in limestone regions; liming the soil may
help eradicate common sheep sorrel .
Common sheep sorrel presence and abundance are indicative of poor and "sour"
soils [82,87]. It reaches peak abundance at low soil nitrogen levels
. Common sheep sorrel is potentially poisonous to livestock because of the
presence of soluble oxalates ; however, it is grazed by sheep and
cattle . In Idaho common sheep sorrel is an increaser species under heavy
grazing regimes, and a decreaser species under light grazing regimes
. In Oregon percent frequency of common sheep sorrel was not affected by
late season cattle grazing in a riparian mountain meadow .
In Novia Scotia common sheep sorrel is one of the most common weed species in
lowbush blueberry fields. Control with hexazinone was attempted but
after the activity of the herbicide decreased, common sheep sorrel grew and
produced a large number of seeds . In Pennsylvania in a goldenrod
(Solidago spp.)-aster (Aster spp.) community, common sheep sorrel was dominant
in 1- and 3-year-old plowed, disked, prometone-treated plots .
Control Methods: Repeat cultivation during dry weather gradually
weakens rootstalks of common sheep sorrel . According to Fitzsimmons 
several herbicides can selectively control common sheep sorrel.
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Rumex acetosella
GENERAL BOTANICAL CHARACTERISTICS:
Common sheep sorrel is an introduced rhizomatous perennial herb that sometimes
forms dense colonies by adventitious shoots from widely spreading roots
and rhizomes [19,29,35,52,92]. Stems are erect, slender, and 4 to 24
inches (10-60 cm) tall [33,72,95]. Leaves are 0.8 to 4 inches (2-10 cm)
long and 0.4 to 0.8 inch (1-2 cm) wide [33,34,72]. The fruit is an
achene [25,29,38,72,95]. Roots are slender, almost fibrous and
penetrate to a depth of 5 feet (1.5 m) .
RAUNKIAER LIFE FORM:
Sexual: Common sheep sorrel reproduces by seed. It is wind pollinated and
seed is dispersed by wind and insects [37,91]. Common sheep sorrel regularly
colonizes from buried seed following disturbance [14,21,26]. In
Massachusetts common sheep sorrel was not present in the ground cover of most
eastern white pine and red pine (Pinus resinosa) stands, but seeds were
contained in soil samples from 1-to 80-year-old stands. In the
laboratory soil-stored seeds from all stands germinated .
Vegetative: Common sheep sorrel reproduces from creeping roots and rhizomes
[2,16,48,77]. Shoots develop from stem buds that arise adventitiously
at irregular intervals on horizontal roots. Adventitious buds are
usually found in the top 8 inches (20 cm) of soil .
Common sheep sorrel is common in fields, pastures, meadows, waste places, and
along roadsides [4,29,39,46,72,95]. In Olympic National Park,
Washington, common sheep sorrel is commonly found on lower terraces and gravel
bars of the riparian zone [1,13,63]. Common sheep sorrel is generally found in
open, unshaded areas on disturbed sites [29,92,95]. It thrives on
acidic soils with low fertility, but is adapted to a variety of soil
types [19,29,96]. Common sheep sorrel is commonly found on sandy loam, fine
sandy, silty, and gravelly soils [6,7,14,58,99].
Elevations for common sheep sorrel are as follows:
Arizona 5,500-8,000 1,650-2,400 
California 0-9,900 0-3,000 
Colorado 4,000-11,200 1,200-3,360 [33,100]
Connecticut 1,020-1,050 310-320 
Idaho 2,800-6,000 853-1,830 [65,99]
Montana 3,300-6,200 990-1,860 
New York 900-1,700 270-510 
Oregon <4,000 <1,200 
Utah 4,500-9,100 1,350-2,730 [95,100]
Washington <4,000 <1,200 
Wyoming 6,000-9,000 1,800-2,700 
Common sheep sorrel invades disturbed sites and may move onto undisturbed sites
when growing conditions are ideal [1,16,52,77]. It is commonly found on
clearcut, burned, and flood-disturbed riparian sites [1,13,27,94]. It
colonizes rapidly by seed and may persist for 15 to 20 years through
vegetative growth and propagation . Competition from other species
on good soils may reduce its abundance .
In South Carolina common sheep sorrel is found in the early seral stages of a
disturbed old-field broomsedge bluestem (Andropogon virginicus)
In the Pacific Northwest common sheep sorrel seed generally remains viable in
the soil long enough to provide a source of new infestations when the
soil is disturbed . In Massachusetts buried common sheep sorrel seed
germinated from soil samples from eastern white pine and red pine stands
1 to 80 years old .
Common sheep sorrel is moderately shade tolerant. In the foothills of the
Sierra Nevada and Coast Ranges, California, common sheep sorrel was more
abundant under dead blue oak (Quercus douglasii) trees (5.7%) than in
open grassland (5.2%) or live blue oak stands (<0.1%) .
Common sheep sorrel flowering dates are as follows:
California Mar-Aug 
Idaho May-Sept 
Georgia Mar-Jun 
Kansas Apr-July 
Montana May-Aug 
North Carolina Mar-July [72,98]
North Dakota May-Jun 
Oregon May-Sept 
South Carolina Mar-July [72,98]
Tennessee Mar-Jun 
Virginia Mar-Jun 
Washington May-Sept 
West Virginia May-Sept 
Great Plains Apr-Aug 
SPECIES: Rumex acetosella
FIRE ECOLOGY OR ADAPTATIONS:
Common sheep sorrel probably survives fire by sprouting from rhizomes and
roots [47,72]. It probably regenerates from on-site buried seed.
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find Fire Regimes".
POSTFIRE REGENERATION STRATEGY:
Rhizomatous herb, rhizome in soil
Ground residual colonizer (on-site, initial community)
Secondary colonizer - off-site seed
FIRE MANAGEMENT CONSIDERATIONS:
SPECIES: Rumex acetosella
IMMEDIATE FIRE EFFECT ON PLANT:
Common sheep sorrel is probably top-killed by fire.
PLANT RESPONSE TO FIRE:
Common sheep sorrel probably sprouts from rhizomes following fire and
establishes from on-site seed [14,21,26]. Several studies describe
establishment or increase of common sheep sorrel after fire. Very severe fire
may kill common sheep sorrel.
In New Brunswick a woodlot was clearcut in the fall of 1949 and
prescribed burned in April 1951. The number of stems of common sheep sorrel
per area present in June 1949, 1950, 1951, and 1952 were 0, 0, 18, and
28, respectively . In New Brunswick understory layers of 11 mixed
hardwood stands representing an age sequence of 7 to 57 postfire years
were examined. Sampling occurred in July and August 1973 and 1974.
Common sheep sorrel was found in stands 7, 10, 13, 17, and 25 years old. It
did not occur in some 7-year-old stands, or in stands 18, 20, 29, and 37
years old .
In Idaho seral brushfields in a grand fir/pachistima habitat type were
prescribed burned on May 14, 1975, and a portion was seeded on May 15,
1975. Common sheep sorrel was present on the burn-only area, but did not occur
on the burn-and-seed site. Frequency (out of 10 possible plots) of
common sheep sorrel was as follows :
Prefire Postfire year
July 3, 1974 1 2 4
control 1 2 3 3
burn only 0 0 5 4
burn and seed 0 0 0 0
In Idaho a wildfire burned a ponderosa pine (Pinus ponderosa) forest and
adjacent montane grassland on August 10, 1973 for 43 days. Fourteen
sites were examined in June 1974 and June 1976. Percent cover and
frequency of common sheep sorrel on burned and unburned sites were as follows
burned unburned burned unburned
cover +/- SD t* +/- 1 t +/- t 2 +/- 3 1 +/- 2
frequency +/- SD 1 +/- t t +/- 1 2 +/- 4 1 +/- 2
*t = trace
In Washington on the Mount Adams huckleberry (Vaccinium spp.) fields,
an experimental area was prescribed burned from October 3-7, 1972.
Average understory cover (%) of common sheep sorrel from 1972 to 1977 was as
1972 (before treatment) 1973 1974 1975 1977
unburned, uncut 0.2 0.2 0.3 0.3 0.2
thin, underburn 0.2 0.6 0.9 1.2 1.5
clearcut and burn 0.2 0.9 1.9 1.0 1.6
In Great Britain severe fires in late summer 1976 killed all surface
vegetation. Common sheep sorrel first appeared in burned areas in October
1985, postfire year 9 .
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
Some research describes no change in cover or frequency in common sheep sorrel
after fire. In California the effects of a late fall burn on a mountain
meadow in Grover Hot Springs State Park were evaluated. Both wet and
dry meadow plots were prescribed burned by a low- to moderate-intensity
fire in mid-November 1987. Common sheep sorrel was found only on dry plots
before burning and did not increase following fire .
In Connecticut experimental tracts were set up in a little bluestem
grassland in 1967. Tract A was prescribed burned annually from
1968-1976, and in 1978, 1980, 1983, and 1985. Tract B was prescribed
burned annually from 1968-1975, and in 1978, 1980, 1983, and 1985.
Common sheep sorrel percent cover and frequency in two burns and 2 control
plots on each tract were as follows :
Tract A Tract B
1967 1985 1967 1985
cover freq cover freq cover freq cover freq
Burn <1 9 2 6 <1 29 <1 5
Control <1 22 0 0 1 65 <1 27
The following Research Project Summaries provide information on prescribed
fire use and postfire response of plant community species, including common sheep sorrel,
that was not available when this review was originally written:
SPECIES: Rumex acetosella
1. Agee, James K. 1988. Successional dynamics in forest riparian zones. In:
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plasticity and survival following burial by volcanic tephra. Canadian
Journal of Botany. 63: 2083-2090. 
3. Auchmoody, L. R.; Walters, R. S. 1988. Revegetation of a brine-killed
forest site. Soil Science Society of America Journal. 52: 277-280.
4. Bare, Janet E. 1979. Wildflowers and weeds of Kansas. Lawrence, KS: The
Regents Press of Kansas. 509 p. 
5. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals,
reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's
associations for the eleven western states. Tech. Note 301. Denver, CO:
U.S. Department of the Interior, Bureau of Land Management. 169 p.
6. Biswell, H. H. 1956. Ecology of California grasslands. Journal of
Forestry. 9: 19-24. 
7. Blewett, Thomas. 1978. Prairie and savanna restoration in the Necedah
National Wildlife Refuge. In: Glenn-Lewin, David C.; Landers, Roger Q.,
Jr., eds. Proceedings, 5th Midwest prairie conference; 1976 August
22-24; Ames, IA. Ames, IA: Iowa State University: 154-157. 
8. Boyd, Robert S.; Woodward, Roy A.; Walter, Gary. 1993. Fire effects on a
montane Sierra Nevada meadow. California Fish and Game. 70(3): 115-125.
9. Carson, Walter P.; Pickett, S. T. A. 1990. Role of resources and
disturbance in the organization of an old-field plant community.
Ecology. 71(1): 226-238. 
10. Clampitt, Christopher A. 1993. Effects of human disturbances on prairies
and the regional endemic Aster curtus in western Washington. Northwest
Science. 67(3): 163-169. 
11. Clark, Ronilee A.; Fellers, Gary M. 1986. Rare plants of Point Reyes
National Seashore. Tech. Rep. No. 22. Davis, CA: University of
California, Institute of Ecology; San Francisco, CA: U.S. Department of
the Interior, National Park Service, Western Region. 117 p. 
12. Davis, Liam H.; Sherman, Robert J. 1992. Ecological study of the rare
Chorizanthe valida (Polygonaceae) at Point Reyes National Seashore,
California. Madrono. 39(4): 271-280. 
13. DeFerrari, Collette M.; Naiman, Robert J. 1994. A multi-scale assessment
of the occurrence of exotic plants on the Olympic Peninsula, Washington.
Journal of Vegetation Science. 5: 247-258. 
14. Del Tredici, Peter. 1977. The buried seeds of Comptonia peregrina, the
sweet fern. Bulletin of the Torrey Botanical Club. 104(3): 270-275.
15. Dorn, Robert D. 1988. Vascular plants of Wyoming. Cheyenne, WY: Mountain
West Publishing. 340 p. 
16. Escarre, Josep; Houssard, Claudie; Thompson, John D. 1994. An experimental
study of the role of seedling density and neighbor relatedness in the
persistence of Rumex acetosella in an old-field succession. Canadian
Journal of Botany. 72(9): 1273-1281. 
17. Eyre, F. H., ed. 1980. Forest cover types of the United States and
Canada. Washington, DC: Society of American Foresters. 148 p. 
18. Fiedler, Peggy Lee; Leidy, Robert A. 1987. Plant communities of Ring
Mountain Preserve, Marin County, California. Madrono. 34(3): 173-192.
19. Fitzsimmons, J. P.; Burrill, L. C. 1993. Red sorrel: Rumex acetosella L.
Weeds. Corvallis, OR: Pacific Northwest Extension Publication; PNW 446:
20. Fonda, R. W. 1974. Forest succession in relation to river terrace
development in Olympic National Park, Washington. Ecology. 55(5):
21. Fyles, James W. 1989. Seed bank populations in upland coniferous forests
in central Alberta. Canadian Journal of Botany. 67: 274-278. 
22. Gardner, Robert A. 1958. Soil-vegetation associations in the redwood -
Douglas-fir zone of California. In: Proceedings, 1st North American
forest soils conference; [Date of conference unknown]; East Lansing, MI.
East Lansing, MI: Michigan State University, Agricultural Experiment
Station: 86-101. 
23. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others].
1977. Vegetation and environmental features of forest and range
ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of
Agriculture, Forest Service. 68 p. 
24. Gashwiler, Jay S. 1970. Plant and mammal changes on a clearcut in
west-central Oregon. Ecology. 51(6): 1018-1026. 
25. Gleason, Henry A.; Cronquist, Arthur. 1991. Manual of vascular plants of
northeastern United States and adjacent Canada. 2nd ed. New York: New
York Botanical Garden. 910 p. 
26. Granstrom, A.; Schimmel, J. 1993. Heat effects on seeds and rhizomes of
a selection of boreal forest plants and potential reaction to fire.
Oecologia. 94: 307-313. 
27. Granstrom, Anders. 1982. Seed banks in five boreal forest stands
originating between 1810 and 1963. Canadian Journal of Botany. 60:
28. Grant, S. A.; Torvell, L.; Smith, H. K.; [and others]. 1987. Comparative
studies of diet selection by sheep and cattle: blanket bog and heather
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29. Great Plains Flora Association. 1986. Flora of the Great Plains.
Lawrence, KS: University Press of Kansas. 1392 p. 
30. Green, Pat; Jensen, Mark. 1991. Plant succession within managed grand
fir forests of northern Idaho. In: Harvey, Alan E.; Neuenschwander, Leon
F., compilers. Proceedings--management and productivity of
western-montane forest soils; 1990 April 10-12; Boise, ID. Gen. Tech.
Rep. INT-280. Ogden, UT: U.S. Department of Agriculture, Forest Service,
Intermountain Research Station: 232-236. 
31. Hall, I. V. 1955. Floristic changes following the cutting and burning of
a woodlot for blueberry production. Canadian Journal of Agricultural
Science. 35: 143-152. 
32. Hall, Ivan V.; Aalders, Lewis E.; Nickerson, Nancy L.; Vander Kloet, Sam
P. 1979. The biological flora of Canada. I. Vaccinium angustifolium
Ait., sweet lowbush blueberry. Canadian Field-Naturalist. 93(4):
33. Harrington, H. D. 1964. Manual of the plants of Colorado. 2d ed.
Chicago: The Swallow Press Inc. 666 p. 
34. Hickman, James C., ed. 1993. The Jepson manual: Higher plants of
California. Berkeley, CA: University of California Press. 1400 p.
35. Hitchcock, C. Leo; Cronquist, Arthur. 1973. Flora of the Pacific
Northwest. Seattle, WA: University of Washington Press. 730 p. 
36. Holland, V. L. 1980. Effect of blue oak on rangeland forage production
in central California. In: Plumb, Timothy R., technical coordinator.
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of California oaks; 1979 June 26-28; Claremont, CA. Gen. Tech. Rep.
PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service,
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37. Houssard, C.; Escarre, J. 1991. The effects of seed weight on growth and
competitive ability of Rumex acetosella from two successional
old-fields. Oecologia. 86(2): 236-242. 
38. Hulten, Eric. 1968. Flora of Alaska and neighboring territories.
Stanford, CA: Stanford University Press. 1008 p. 
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barley, oat, and wheat-straw mulches in eastern Quebec forest
plantations 1. Effects on red raspberry (Rubus idaeus). Forest Ecology
and Management. 29: 277-294. 
43. Juday, Glenn Patrick. 1992. Alaska Research Natural Areas. 3: Serpentine
Slide. Gen. Tech. Rep. PNW-GTR-271. Portland, OR: U.S. Department of
Agriculture, Forest Service, Pacific Northwest Research Station. 66 p.
44. Kauffman, J. Boone; Krueger, W. C.; Vavra, M. 1983. Effects of late
season cattle grazing on riparian plant communities. Journal of Range
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Elizabeth. 1960. Arizona flora. 2d ed. Berkeley, CA: University of
California Press. 1085 p. 
47. Keown, Larry D. 1978. Fire management in the Selway-Bitterroot
Wilderness, Moose Creek Ranger District, Nez Perce National Forest.
Missoula, MT: U.S. Department of Agriculture, Forest Service, Northern
Region. 163 p. 
48. Kiltz, B. F. 1930. Perennial weeds which spread vegetatively. Journal of
the American Society of Agronomy. 22(3): 216-234. 
49. Kolb, T. E.; Bowersox, T. W.; McCormick, L. H. 1990. Influences of light
intensity on weed-induced stress of tree seedlings. Canadian Journal of
Forestry Research. 20: 503-507. 
50. Krueger, William C.; Donart, Gary B. 1974. Relationship of soils to
seasonal deer forage quality. Journal of Range Management. 27(2):
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perspective. Saranac, NY: The Chauncy Press. 320 p. 
52. Lackschewitz, Klaus. 1991. Vascular plants of west-central
Montana--identification guidebook. Gen. Tech. Rep. INT-227. Ogden, UT:
U.S. Department of Agriculture, Forest Service, Intermountain Research
Station. 648 p. 
53. Leege, Thomas A.; Godbolt, Grant. 1985. Herebaceous response following
prescribed burning and seeding of elk range in Idaho. Northwest Science.
59(2): 134-143. 
54. Leege, Thomas A.; Herman, Daryl J.; Zamora, Benjamin. 1981. Effects of
cattle grazing on mountain meadows in Idaho. Journal of Range
Management. 34(4): 324-328. 
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