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Medusahead

Taeniatherum caput-medusae (L.) Nevski

Broad-scale Impacts of Plant Response to Fire

provided by Fire Effects Information System Plants
More info for the terms: controlled burn, cover, dough stage, fire exclusion, seed

Attempts have been made to destroy medusahead by
prescribed burning in soft-dough stage to destroy the seed crop. Medusahead stands in the milk or early
dough stage (late May or early June) are
cured enough that they can carry a "light" fire that burns through the slender culms
and arrests seed development [42]. However, a "substantial" number of seeds
are not killed by fire [52]. Burning followed by seeding of perennial
grasses may suppress medusahead [17]. If postfire revegetation efforts of
medusahead-infested areas are not timely, erosion will expose the clay subsoil
that the species frequently inhabits [11].  A controlled burn in early June on a ranch in the
Redwood Valley, California, almost completely eliminated medusahead, and the area was still
"relatively" free of medusahead 2 years later [42]. Another California
study found that medusahead cover was significantly reduced (p=0.03) by 74% with
prescribed burning in ungrazed prairie. Coverage was greatest with either summer
grazing or no
grazing and fire exclusion (p=0.013) [71].
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bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Common Names

provided by Fire Effects Information System Plants
medusahead

medusahead wildrye
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bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Conservation Status

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California - C list (noxious weed) [111]

Colorado - A list (noxious weed); C list (noxious weed; not yet widespread or causing economic impact) [110]

Nevada - Y list (noxious weed) [112]

Oregon - B list (noxious weed of economic importance that is regionally abundant but may have limited distribution in some counties) [112]

Utah - noxious weed [113]
license
cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Cover Value

provided by Fire Effects Information System Plants
Medusahead-dominated areas have very low species diversity and low value for
wildlife habitat [79].





OTHER USES AND VALUES:





No entry
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cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Description

provided by Fire Effects Information System Plants
More info for the terms: cool-season, seed, spikelet

Medusahead is a nonnative, cool-season annual grass [49]. Plant
height ranges from 8 to 20 inches (20-50 cm), depending on the site. Plants
produce tillers, but very few leaves [79,83]. Medusahead has a
distinctive flowerhead. The inflorescence contains 2 to 3 spikelets per node, and each spikelet contains 1
seed. Plants produce an average of 7.1 seeds per spike [79,83]. Medusahead has 2 types of awns: both are flat, but the longer of
the 2 contains barbs that point upward [79]. Plants in dense stands usually produce
1 spike; in open areas the number of spikes per plant typically increases
to 3 to 5. An exceptional plant in Idaho produced 133 spikes.
Medusahead-dominated
stands usually have more than 100
plants/ft2. Densities of 1,500 to 2,000 plants/ft2 have been found
on a valley bottom in southern Idaho [99,106].
license
cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Distribution

provided by Fire Effects Information System Plants
Medusahead is native to the Mediterranean region of Europe.
It was introduced into the U.S. in the 1880s [25,29,42,45] but did not spread
rapidly until the 1950s [49]. Medusahead is now established throughout the
U.S. and Canada [66]. It is most common in the western U.S. from British
Columbia south to California and east to Idaho [16,36,57,98,99,105,118,123]. The PLANTS database provides a distributional map of
medusahead in the United States.
license
cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Fire Ecology

provided by Fire Effects Information System Plants
More info for the terms: ecotype, fire regime, frequency, fuel, grassland, herbaceous, litter, seed, severity, shrub, shrubs, stand-replacement fire, succession, wildfire, xeric

Fire adaptations: Medusahead establishes after
fire from
the seed bank and from seed dispersed from off-site sources [10,62,99]. Bioassays
of burned soil after a rapidly spreading, wind-driven fire in California found
viable medusahead fruits within lightly charred litter [10].

FIRE REGIMES: The expansion of exotic annual
grasses such as medusahead has substantially increased frequency of fire in the
western United States [69]. Medusahead has a fine
structure and its herbage dries completely; therefore, its standing dead biomass
is extremely flammable. The hazard of wildfire is further increased by
considerable litter
[41].
Medusahead litter decomposes more slowly than that of most plants [108], therefore
making stands of this annual grass a fire hazard [84]. Slow decomposition
is a result of its high silica content [77,104]: total ash content of
medusahead contains 72 to 89% silica [104]. The long-lasting litter formed by medusahead
is easily ignited and burns readily [79].
Invasion can initiate a cycle where a non-native grass colonizes an
area and provides the fine fuel necessary for the initiation and propagation of
fire. Fires then increase in frequency, area, and possibly severity. Following
these grass-fueled fires, non-native grasses recover more rapidly than native species
and cause a further increase in fire [27]. Frequent fires destroy the shrub component of the
plant community, and
potentially part of the bunchgrass community, without destroying
"significant" amounts of medusahead seed [79].


The non-native grasses cheatgrass and medusahead have invaded the low sagebrush
communities on the volcanic tablelands of northeastern California and northwestern
Nevada. When precipitation is adequate, the interspaces
between sagebrush plants are completely covered by these invasive grasses. The fine fuels of these
plants, and the accumulation of litter of highly
siliceous medusahead, create conditions in which fire is easily
carried. Negative effects of wildfires in this region include erosion of the thin, coarse-textured,
eolian veneer soils
[11]. For example, the herbaceous vegetation of a ponderosa pine/Sandberg bluegrass
in Modoc County, California, included many other native herbaceous species. After a
wildfire, medusahead
excluded almost all other understory species [22].

Historically, the Snake River Plains of Idaho was vegetated with shrub-bunchgrass
communities. The
primary disturbance was patchy stand-replacement fire, occurring every few
decades. Fire usually occurred where sagebrush or other shrubs had grown dense, since bunchgrasses
did not often provide adequate
continuous fuels. With invasion of exotic annuals and increase such as medusahead, historical
patterns of postfire succession have been altered. Fire-free
intervals have been reduced, and shrub-bunchgrass lands are being converted
to annual grassland.
According to Peters and Bunting [88], "the landscape has become more homogenous,
species diversity has decreased, and burns are larger and more continuous."

Xeric big sagebrush (Artemisia tridentata ssp. xericensis), a subspecies with limited
distribution that is sometimes referred to as an ecotype of mountain big sagebrush, is found primarily in western Idaho
and eastern Oregon and is restricted to a zone where the annual precipitation exceeds 12 inches,
the elevation is less than 4,500 feet, and the summers are relatively warm. Many of these
communities are on relatively steep slopes and have a higher potential for human and
lightning-caused fires, resulting in repeated burns. These frequently burned areas are often
dominated by cheatgrass and medusahead [72].

The range of fire intervals reported for some species that dominate
communities in which medusahead occurs are listed below. Find further 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".

Community or Ecosystem Dominant Species Fire Return Interval Range (years)
California chaparral Adenostoma and/or Arctostaphylos spp. < 35 to < 100
sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [86]
basin big sagebrush Artemisia tridentata var. tridentata 12-43 [96]
mountain big sagebrush Artemisia tridentata var. vaseyana 20-60 [3,21]
Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (40)** [115,122]
blue grama-needle-and-thread grass-western wheatgrass Bouteloua gracilis-Hesperostipa comata-Pascopyrum
smithii < 35
cheatgrass Bromus tectorum < 10
California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100
western juniper Juniperus occidentalis 20-70
Rocky Mountain juniper Juniperus scopulorum < 35
wheatgrass plains grasslands Pascopyrum smithii < 35
pinyon-juniper Pinus-Juniperus spp. < 35 [86]
Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-300+ [1,2,95]
Sierra lodgepole pine* Pinus contorta var. murrayana 35-200
Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [2]
mountain grasslands Pseudoroegneria spicata 3-40 (10)** [1,2]
Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [2]
coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [2,82,91]
California mixed evergreen Pseudotsuga menziesii var. m.-Lithocarpus
densiflorus-Arbutus m. < 35 [2]

*fire return interval varies widely; trends in variation are noted in the
species summary

**(mean)
license
cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Fire Management Considerations

provided by Fire Effects Information System Plants
More info for the terms: competition, cover, density, dough stage, fuel, fuel moisture, herbaceous, litter, seed, shrub, shrubs

Wildfires facilitate replacement of native grasses with
these annual grasses [38,80]. However, burning may be an effective means of reducing dominance if
plants are burned early enough in the season to scorch culms and seeds, preventing seed
maturation [30]. Compared to chemical or cultivation treatments, burning provides a relatively
economical, although highly variable, means of controlling medusahead [83].
Preliminary results from Oregon indicate that glyphosate treatment and mowing 1 year
following summer prescribed burning were equally effective at reducing medusahead and
cheatgrass cover [89]. The heat of
the fire should be concentrated to burn as many seeds in the head as
possible. This can be achieved by having the fire move slowly so as to
obtain complete fuel consumption. Slow, "hot" fires kill the greatest number of
seeds, and this can be achieved by burning downhill or into the wind [75,77,83].

Early-season burns, conducted before medusahead seeds have ripened, are effective if
associated plants have dried enough to provide fuel for a fire [75]. Burning
medusahead during the soft dough stage is effective because the high moisture content in the seed
increases the effects of burning
[77]. Dense patches of green medusahead will often remain unburned unless previously sprayed
with oil. Some recommend later-season burns, after medusahead seeds have ripened
but before they drop. Seeds of most herbaceous species will have dropped by
then,
and will be less susceptible to fire damage [75]. An
effective management strategy in central Oregon is burning medusahead in late
spring or early summer before the seeds have dropped off the plant, and
following the next spring with an herbicide treatment of glyphosate after remaining seeds have
germinated. However, this herbicide treatment is not recommended when reseeding is required since
it is a broad-spectrum non-specific treatment [79]. It is recommended that reburning
not occur more than once every 2 to 3 years if an adequate stand of forage
plants is to be established [75]. A California study found medusahead burned
well at relative humidity of 40 to 50% and temperature 60 to 70 degrees
Fahrenheit (16-21 oC); however, a temperature of 90 degrees Fahrenheit (32
oC) and relative
humidity of 30% was considered too severe [42]. In another test, best burning
conditions for consuming medusahead were experienced around noon with air
temperature of 99 degrees Fahrenheit (37 oC), relative humidity 23%, and wind
speed of 11 mph (17 km/hr). Other California studies suggest that relative humidity of about
40% is not optimal for igniting dry grass [42,77].

Fire's effectiveness in reducing stands of medusahead on rangeland depends
on burning conditions, including time of day and season of burn. Fire
can be an effective tool in removing old medusahead litter, reducing density of medusahead stands, reducing the medusahead
seed bank, and
minimizing damage to desirable associated species. The following are
conditions present during burns of medusahead-infested rangeland at the R. E.
Shellhammer Ranch in Solano County, California 1959 [77].

Date and time
oF (oC)
Relative  humidity (%)
Wind velocity (mph)
Fuel moisture (% )
Type of burn
Speed of fire (ft/min)
Duration of fire
at pyrometer(sec)
Aug. 26

7:15 am
12:45 pm
8:50 pm


 

65(18)
102 (39)
70(21)


 

75
20
57


 

5
10
15


 

8.9
3.0
5.2


 

slow/fast
slow/fast
slow/fast


 

1.2/20
6/40
6/80


 

50/22
20/15
25/10



Aug. 28

7:20 am
12:30 pm
  6:45 pm


 

62(17)
94(34)
84(29)


 

92
28
30


 

2
5
15


 

16.4
3.3
3.1


 

slow/fast
slow/fast
slow/fast


 

1/9
6/20
3/40


 

35/25
40/10
50/20



Aug. 31

7:10 am
12:45 pm
  6:45 pm


 

53(12)
102(39)
95(35)


 

93
21
20


 

3
18
10


 

8.0
5.0
2.0


 

slow/fast
slow/fast
slow/fast


 

3/18
6/144
5/105


 

35/20
25/30
27/30



Mean

7:15 am
12:40 pm
7:10 pm


 

60(16)
99(37)
83(28)


 

87
23
39


 

3
11
13


 

11.3
3.5
3.5


slow/fast 4/53 53/18

Slow, hot fires are most desirable for reducing medusahead. In this
study, the most effective control of medusahead was obtained by late
afternoon fires that burned slowly (into a mild wind), ignited when seed was in the soft-dough
stage [77].

Blaisdell and others [9] suggest that each situation be carefully examined and evaluated before
burning can be prescribed as a plant control measure, and emphasize that areas with a poor stand
of desirable perennials prior to burning will probably require seeding to provide satisfactory
forage production and delay return of sagebrush or other unwanted species such as medusahead,
cheatgrass, or halogeton (Halogeton glomeratus) [71]. Young and Evans [120,121] determined that 2 perennial grass plants per square foot
(2.5 per m2) is the minimum necessary to preempt invasion by nonnative annual species and/or
shrub seedlings.

Small roadside burns in southeastern Los Angeles
ponderosa pine woodlands often become dominated by medusahead and cheatgrass. These
communities often accumulate fuel contributing to repeated and increasingly
larger fires. These cycles can be interrupted by immediate seeding
in the burned areas with perennials.
However, if the annuals are established, competition must be reduced before
desirable perennial herbs, shrubs, and/or trees can establish. On
sites marginal for conifers, a combination of all 3 is often desirable [22].
license
cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Growth Form (according to Raunkiær Life-form classification)

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More info for the term: therophyte

RAUNKIAER [90] LIFE FORM:




Therophyte
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Habitat characteristics

provided by Fire Effects Information System Plants
More info for the terms: competition, grassland, herbaceous, mesic

Medusahead grows in areas
that have relatively mild to cold temperatures in winter but are hot in summer [75,79].
It is generally found
in areas that receive fall, winter, and spring moisture followed by dry summers
[108]. It occurs in areas with annual precipitation
of 10 to 40 inches (250-1,000 mm), with an
upper limit of precipitation approximately 50 inches (1,270 mm) [75,79,99]. Infestations
primarily occur in former sagebrush-grass or bunchgrass communities that
receive 10 to 20 inches (250-500 mm) of precipitation [79,99]. Areas above 4,500 feet (1,370 m) elevation, and well-drained
coarse soils, may be less susceptible to invasion. 


Medusahead often dominates disturbed areas on soils with high moisture-holding
capacities and slow percolation rates [33]. Sites particularly susceptible to medusahead invasion
in the more arid portions of Idaho are either those with well-developed soil
profiles, particularly with high clay content either at or near the surface; or
those occupying topographic positions that receive additional run-off from
adjacent sites. In more mesic climates, moderately well-developed soils are as susceptible
to invasion as well-developed soils. Conversely,
soils with little profile development, particularly those that are well
drained, remain dominated by cheatgrass in early seral stages regardless of
whether they are in a more arid or mesic area [28].



In a northwestern California site where medusahead is prevalent, 60% of the vegetation is grassland
or woodland/grass. The climate is mediterranean, with cool wet winters and hot
dry summers. Mean annual rainfall is 39 inches (980 mm). Soil is fine sandy loam
2 to 3.3 feet (0.6-1.0 m) deep with rapid surface drainage; slope is 10% on a southeast aspect [5,6].
Foothills in southwestern Oregon where medusahead is found have silty clay loam
soil, with 1,600 feet (500 m) elevation and 20-30% slope on a west aspect. On southwest aspects,
medusahead occurs on
5-20% slopes at 2,000 feet (600 m) elevation. The climate has a
mediterranean/maritime pattern with cool, wet winters and hot dry summers and annual
precipitation of 20 inches (500 mm) [14].


Medusahead and cheatgrass are often in
competition with each other, and soil and topographic factors affect
their distribution [28,39]. Each can replace other herbaceous vegetation and
share dominance with the other. Cheatgrass occupies a
larger geographical area than medusahead, extending to drier areas of the
semiarid western U.S. than does medusahead [29].
Cheatgrass will grow in almost any type of soil, although it does best on deep, loamy or
coarse-textured soils and it does not grow as well on fine textured soils (e.g. [32,73,125]).
Medusahead may be more likely to dominate on fine-textured soils in the Intermountain region [118].
In arid conditions, medusahead is more dependent on additional moisture for
survival. This may be because cheatgrass matures when soil moisture is still
plentiful in May, and medusahead does not mature until 3 weeks later when
moisture is more confined to depressions and clay soils [28,39]. Because medusahead matures
approximately 1 month later than cheatgrass, it initially only replaces cheatgrass on soils with
sufficient moisture holding capacity, such as clay textured soils, so that some
soil moisture remains after cheatgrass matures. Medusahead's root system can exploit all soil moisture in the soil profile
[117]. In the Columbia River Basin, medusahead is dominant on
soils high in montmorillonite clay within 10 to 12 inches (25-30 cm) of the surface,
and on soils low in clay but on with favorable topographic positions.
Cheatgrass is dominant on weakly developed soils low in montmorillonite clay.

license
cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Habitat: Cover Types

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the term: cover

SAF COVER TYPES [37]:




218 Lodgepole pine

219 Limber pine

220 Rocky Mountain juniper

237 Interior ponderosa pine

238 Western juniper

239 Pinyon-juniper

245 Pacific ponderosa pine

247 Jeffrey pine
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cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Habitat: Ecosystem

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

ECOSYSTEMS [43]:




FRES21 Ponderosa pine

FRES22 Western white pine

FRES23 Fir-spruce

FRES24 Hemlock-Sitka spruce

FRES25 Larch

FRES26 Lodgepole pine

FRES29 Sagebrush
FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper
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bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Habitat: Plant Associations

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

KUCHLER [70] PLANT ASSOCIATIONS:




K001 Spruce-cedar-hemlock forest

K002 Cedar-hemlock-Douglas-fir forest

K003 Silver fir-Douglas-fir forest

K004 Fir-hemlock forest

K008 Lodgepole pine-subalpine forest

K011 Western ponderosa forest

K012 Douglas-fir forest

K013 Cedar-hemlock-pine forest

K014 Grand fir-Douglas-fir forest

K015 Western spruce-fir forest

K025 Alder-ash forest

K038 Great Basin Sagebrush

K055 Sagebrush steppe
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bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Habitat: Rangeland Cover Types

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: cover, shrubland, woodland

SRM (RANGELAND) COVER TYPES [101]:




101 Bluebunch wheatgrass

102 Idaho fescue

104 Antelope bitterbrush-bluebunch wheatgrass

107 Western juniper/big sagebrush/bluebunch wheatgrass

109 Ponderosa pine shrubland

110 Ponderosa pine-grassland

401 Basin big sagebrush

402 Mountain big sagebrush

403 Wyoming big sagebrush

406 Low sagebrush

408 Other sagebrush types

412 Juniper-pinyon woodland

606 Wheatgrass-bluestem-needlegrass

607 Wheatgrass-needlegrass

608 Wheatgrass-grama-needlegrass
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Immediate Effect of Fire

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More info for the term: density

Fire kills mature medusahead plants. Immature plants may be only top-killed by
early-season fire, and regenerate by tillering [79,83]. Fire also destroys many viable medusahead seeds, but sufficient numbers remain uninjured
that reduction in plant density is usually temporary [76,99].
license
cc-publicdomain
bibliographic citation
Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Importance to Livestock and Wildlife

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More info for the terms: cover, herbaceous, litter, seed, wildfire

Medusahead is a major concern to the range livestock industry because it can
suppress desirable vegetation. It is
unpalatable to livestock. When dry, dead vegetation
decomposes slowly and forms a persistent dense litter on the soil
surface. As the plant matures it develops long barbed awns
that can cause injury to the eyes, noses, and mouths of grazing animals
[16,51]. Medusahead has little to no feed value to livestock at any stage of growth
[13,16,83,106]. However, it has been noted that livestock utilize it when
other feed is
limited [83].


Medusahead is not important to wildlife forage [13].
It has invadesd and replaced dense stands of cheatgrass [48,78]
over large areas in California, Idaho, Oregon, and Washington during the past 40 years [124].
Medusahead herbage is less palatable to ungulates than cheatgrass, and reduces grazing capacity
where it replaces cheatgrass [47]. Its seeds are not digestible by upland game birds, which
are large consumers of cheatgrass seeds [92]. Medusahead seed appears to be largely indigestible to chukar and other wild birds
[79,97]. In a controlled study, chukar in medusahead- infested areas ingested
medusahead fruits. However, when diet was limited to medusahead seeds, dramatic weight loss
occurred [97]. Rabbits may occasionally
graze medusahead [99].


Mule deer generally use medusahead very little. A northeastern
Oregon medusahead-rattail fescue (Festuca myuros)-soft chess (Bromus
mollis) community received some spring
and summer use. However, despite the extensive
stands available, medusahead was still the least preferred forage of mule deer
in winter, summer, and fall, and it ranked low in spring. Communities dominated by medusahead
were of little value to mule deer, while cheatgrass-dominated communities receive substantial
use [14]. The dwarf sagebrush species such as low sagebrush and black sagebrush (Artemisia nova)
are
preferred mule deer browse. Medusahead has established in some dwarf sagebrush communities,
and the invasion of such sites by
medusahead has increased the incidence of wildfire as reduced cover of dwarf
sagebrushes. These sites
had previously been considered "fireproof" because of
reduced herbaceous vegetation caused by excessive grazing [23].

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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Key Plant Community Associations

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More info for the terms: association, forbs, herbaceous, wildfire

Medusahead and cheatgrass (Bromus tectorum), another invasive non-native
species, overlap in distribution and habitat requirements. Each can replace other herbaceous vegetation and
share dominance with the other. Cheatgrass occupies a
larger geographical area than medusahead, which extends to drier areas of the
semi-arid western U.S. [29]. Medusahead maintain its dominance on sites where native
vegetation has been eliminated or severely reduced by overgrazing, cultivation,
or frequent fires [102]. It has invaded seral communities in eastern
Oregon and Idaho and replaced cheatgrass as the dominant alien grass [57]. It has invaded fields, dry roadsides,
and disturbed sagebrush slopes
in British Columbia, Washington, Idaho, Oregon, and California [26,58,60].

Great Basin:
On sagebrush (Artemisia spp.)-dominated habitats in western Great Basin, medusahead usually invades
sites already infested with cheatgrass
[77,93,109,117,118]. In
California, medusahead colonies often border low sagebrush (Artemisia
arbuscula ssp. longicaulis) communities [11]. Associated grasses
in sagebrush-dominated communities with a medusahead component include bottlebrush squirreltail (Elymus
elymoides), Sandberg bluegrass
(Poa secunda) [118], foxtail fescue (Festuca megalura), bluebunch wheatgrass
(Pseudoroegneria spicata), and crested wheatgrass (Agropyron desertorum)
[7,46,49,51,81,99]. Forbs
associated with medusahead in the Great Basin include sunflower (Helianthus annuus) [98,118],
panicle willowweed (Epilobium paniculatum), and gumweed (Grindelia
nana) [118].


A Nevada study found that sites
with sparse native plants are more susceptible to medusahead invasion
than more diverse low sagebrush (Artemisia arbuscula) or woodland/low
sagebrush
communities. If the more diverse communities are degraded
to a "low" seral state, medusahead can invade and occupy the site. Young and
others [119] determined that low sagebrush communities are most susceptible to medusahead
invasion, while big sagebrush (A. tridentata) communities are more resistant [118].



Pacific Northwest:
Forbs commonly associated with medusahead
in this region include yellow starthistle (Centaurea solstitialis), western
yarrow (Achillea millefolium), and arrowleaf balsamroot (Balsamorhiza
sagittata) [7,94,100]. Grasses associated with medusahead include bluebunch
wheatgrass and crested wheatgrass [49]. A
bristly dogstail grass (Cynosurus schinatus)/medusahead association has
been described for cattle and domestic sheep rangelands in the Umpqua River Basin
of Oregon. Medusahead is also
described as a dominant understory species in Oregon white oak/poison-oak (Quercus
garryana/Toxicodendron diversilobum)/medusahead woodlands of the
Umpqua River Basin [102]. Northern California study sites from Fall River Mills to Davis
Creek, established after a wildfire, showed that medusahead formed
extensive colonies on sites formerly dominated by ponderosa pine
(Pinus ponderosa) or western juniper (Juniperus occidentalis) [118].
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Life Form

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More info for the term: graminoid

Graminoid
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Management considerations

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More info for the terms: competition, fire tolerant, prescribed fire, seed, wildfire

The introduction and subsequent rapid spread of
medusahead has caused serious management concern because of its rapid migration,
vigorous competitive nature, and low forage value. A study by the BLM found
that on public lands administered by the
agency, 3.3 million acres of rangeland are classified as cheatgrass and/or medusahead
monocultures; nearly 14 million acres are infested with 1 or both; and 62.1
million acres are at risk of invasion by these 2 grasses if disturbance occurs
[87]. In some infested areas of southwestern Idaho, it
has reduced grazing capacity as much as 80% [28].
Medusahead invasion has shifted the balance from a
shrub/perennial grass ecosystem to an annual grass-dominated ecosystem [11].

A healthy stand of
perennial vegetation appears to be the best barrier to medusahead invasion [28].
Medusahead invasions are most common on ranges in poor condition. Poor grazing management practices may accelerate the rate of
spread, but proper management alone may not prevent invasion [42]. Cultivated areas are susceptible to
invasion by medusahead, especially old fields. Livestock avoid medusahead when
more palatable forage is available, leading to an abundance of soil-stored
medusahead seed [83]. A combination of treatments including grazing, burning,
mechanical manipulation, herbicide such as atrazine or glyphosate, and/or reseeding are generally necessary to reduce
established stands of medusahead [22,75,79,106].


Mechanical:
Spring
plowing after most medusahead has germinated has given some control, with optimal
results reaching 95% reduction. Besides removing
weeds and preparing a seedbed for native herbs, cultivation may bury some medusahead seeds so
deeply that they cannot emerge. Spring cultivation eliminates medusahead seedlings, and
legumes can then be drilled at a rate of at least 10 pounds per acre [75]. It is best to
sow in late autumn or early spring, using a rangeland drill if possible. Killing
2 successive crops of annual weeds helps ensure the survival of seeded species
[79]. Cultivation method may not be practical in some terrain, such as the generally steep
and rocky terrain of Idaho's medusahead-infested rangelands [79,106].


Grazing and fire:
Vegetative
manipulation, including fire, may benefit cattle and mule deer on
medusahead-dominated sites  [77]. Burning
medusahead can destroy large amounts of seeds if the seedhead has not
disseminated, reducing the stand by 60 to 95% in the next growing season [51]. A slow
burn in dense medusahead stands that occur on well-developed soil profiles may reduce seed production. On less developed soil
profiles where prescribed fire is not feasible, grazing livestock when plants are
actively
growing, herbicide treatment, reseeding, or a combination of these methods may be tried
[14,77]. See the "Fire management" section of the Fire Effects section of this
report for further information on controlling medusahead with prescribed
fire.


Reseeding: Revegetation with natives may prevent medusahead from
regaining dominance after control treatments [75]. Reseeding of treated sites should be done with
species that are competitive, have high vigor, and are adapted to the area [79]. The following may be effective: bottlebrush squirreltail, bluebunch wheatgrass, intermediate wheatgrass (Elytrigia
intermedia), Thurber needlegrass (Achnatherum
thurberianum),
needle-and-thread grass (Hesperostipa comata), Indian ricegrass (A.
hymenoides),
Sandberg bluegrass, and sheep fescue (Festuca ovina) [79,106,107].
Bottlebrush squirreltail may be an especially promising candidate for restoring
rangeland dominated by undesirable exotic grasses such as medusahead. It germinates readily, self pollinates, rapidly reaches reproductive
maturity, and is capable of growth in cool temperatures [4,63]. Bottlebrush squirreltail seedlings appear better able to store
sufficient carbohydrate root reserves under competition with annuals than most
other perennial grass species in the Intermountain region
[56]. Bottlebrush squirreltail is also fire
tolerant and has excellent seed dispersal. Since bottlebrush squirreltail
typically occurs in early seres, wildfire or prescribed burns may provide
opportunities for it to establish [63].



A study in Washington found that 'Secar' bluebunch wheatgrass did not
successfully compete with medusahead seedlings on semiarid range sites.
The perennial wheatgrass seeds germinate more slowly and the seedlings grow more slowly
both in length and mass [44].
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Nutritional Value

provided by Fire Effects Information System Plants
Medusahead has very low forage value, except for a short period in the spring
[49,106]. The plant has extremely high silica content, making it unpalatable to livestock [11]. This high silica content may be
partially if not entirely responsible for medusahead's unpalatability to
livestock and its resistance to decomposition. The total ash of the entire
plant contains 72-89% silica [104].
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Occurrence in North America

provided by Fire Effects Information System Plants
AL AK AZ AR CA CO CT DE FL GA
HI ID IL IN IA KS KY LA ME MD
MA MI MN MS 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
DC PR VI


AB BC MB NB NF NT NS NU ON PE

PQ SK YK


MEXICO

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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Palatability

provided by Fire Effects Information System Plants
Palatability of medusahead is apparently variable. Some researchers conclude that the annual
grass is unpalatable at all times [11,24,104], while others determine it may be
"reasonably palatable" in early vegetative stages with rapid decline
in palatability as it matures [42,51,74]. A study in California found that domestic sheep
eat medusahead at every growth stage, but use decreases at plant
maturity. Percentage of medusahead eaten by sheep dropped
from 52% in February to 24% in June [74]. When given free choice, some domestic
sheep will eat medusahead when it is green, and when confined to the plant,
sheep will eat some even when headed out and dry [68]. In early spring medusahead is grazed limitedly by
all classes of livestock, especially if medusahead is associated with more
desirable forage. However, infested areas
are avoided by livestock as soon as flowerheads appear [42]. Although medusahead remains green and succulent
approximately 2 weeks longer than cheatgrass, it is less palatable
[24,31,49,50,51], often
reducing grazing capacity 50-75% where it replaces cheatgrass [50].
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Phenology

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More info on this topic.

More info for the terms: cool-season, dough stage, mesic, phenology, seed

Medusahead is a cool-season annual, and temperature is an important factor in controlling
its phenology. Medusahead germinates during autumn, late winter, or
early spring [25,79]. It usually germinates in October and continues to grow
through the winter in mesic climates. During winter, growth is slowed markedly
with low temperatures, and the plant resumes active growth when the temperature
increases at the beginning of spring [25]. Leaves, stems and roots increase in number through
the winter and roots can reach 40 inches (100 cm) depth by early February [51]. This allows
medusahead to outcompete desirable grasses such as bluebunch wheatgrass [44,51].
Growth accelerates in the spring; by late May or early June, seeds are in the
milk or early dough stage [42]. Seed are generally mature by late June to early July, a few weeks
later than most annual grasses [79]. Seeds remain in spikes until dispersal in late summer
or early fall [99]. Late maturity and greater availability of
soil moisture late in the growing season allow medusahead to reach
maturity and produce large amounts of seeds, which might enhance
site occupation in subsequent generations [29]. Medusahead phenology was as
follows in northern Idaho [16]:

Date Development
May 9 Leaf
May 23 Flowerbud
June 6 Flower
June 21 Late Dough
July 3 Mature
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Plant Response to Fire

provided by Fire Effects Information System Plants
More info for the terms: fuel, litter, seed, wildfire

Medusahead increases under frequent fires at the expense of native species and
sometimes, cheatgrass. It promotes further frequent fire by increasing fuel
loads [27,76]. Accumulated medusahead litter enables stand-replacement fires to occur in
ecosystems such as low sagebrush sites that,
under "pristine" conditions, may have been fire-resistant
[11,116,119,122]. Wildfires in medusahead-infested
areas usually minimally damage
soil surfaces and soil erosion is limited, but enough medusahead seed survives to
produce thinned, vigorous stand of multiculmed medusahead plants the following year. Within
a few years, stand densities approach prefire levels [54].

In cheatgrass and medusahead wildfires, accumulation of litter and the rapidity at which the litter
combusts lead to soil heating of
such short duration that nitrate levels may increase. Wildfire-induced increases
in soil nitrate in cheatgrass and medusahead-dominated areas are undesirable: Medusahead is nitrophilic
and readily germinates in seedbeds with high nitrate levels. Near Alturas, California, a wind-driven wildfire
rapidly spread across a medusahead-dominated area. The litter did not completely
ash and there were still viable medusahead fruits in the lightly
charred litter. Bioassays of the burned soil found over 6.2x106
germinable seeds of medusahead per acre (unpublished data; R. R. Blank, USDA/ARS,
Reno, NV) [10].



Fire eliminates some medusahead seed and removes medusahead litter. It also places the
remaining seed in contact with mineral soil where it can germinate and
subsequently be destroyed by future treatments such as tillage and herbicide use
[108]. Contact with aqueous slurries of heated soil significantly (p<0.05) reduced the rate
and success of emergence of medusahead
seedlings compared with a control [12].

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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Post-fire Regeneration

provided by Fire Effects Information System Plants
More info for the terms: ground residual colonizer, initial off-site colonizer

POSTFIRE REGENERATION STRATEGY [103]:




Ground residual colonizer (on-site, initial community)

Initial off-site colonizer (off-site, initial community)
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Regeneration Processes

provided by Fire Effects Information System Plants
More info for the terms: duff, floret, litter, seed

Medusahead is
entirely dependent upon seed production for regeneration. It is an extremely capable
seeder because of its large annual
production of viable seed, and because its seed maintains viability in
litter and soil for at least 1 year [99]. Medusahead maintains a
short-lived seedbank [10,62,99]. Plants produce up to 6,000 seeds/ft2
of soil, propagating dense
stands in succeeding years [75]. Medusahead is principally self fertile. Most of the
pollen grains are dispersed within the floret and only a moderate number of
pollen grains are produced in each of the short anthers [41]. Some
cross-pollination is effected by wind [18]. 


Animals, wind, and water disperse the seed, and spread is rapid
[42]. A long, rough awn aids in animal dispersal of seed, and medusahead often 1st establishes along
domestic sheep and cow trails [83]. Seeds are dispersed primarily from the coats
and intestinal tracts of grazing animals [42,75,99,109]. Germinable seeds have been recovered in fecal material 4
to 9 days after ingestion by rabbits and domestic sheep, respectively [99]. Stiff barbs pointing in
1 direction enable the
seeds to work into the duff and top layers of the soil. Seeds may germinate in fall, winter, or
spring;
fall germination is most common [6,99,116]. Seedlings
from all seasons produce seeds by early summer [116]. Seeds germinating
in the top layer of litter without soil contact may die during the 1st dry
spell [61,75]. Medusahead usually germinates faster than its competitors. Germination
has been observed 8 to 10 hours after moistening at 50 degrees
Fahrenheit (10 oC) [49]. Germination rates are often over 90% [99]. Awn removal
increases the percentage of germination [85].

A Nevada study found that medusahead seedling emergence and growth
is favored by soil movement and pitting of the soil surface because these
conditions maintain favorable soil temperatures and moisture levels [35]. Favorable microsites for germination and
establishment of medusahead are created when plant litter covers the soil
surface. In Nevada, emergence of medusahead germinants under litter was 47 times greater
than emergence of germinants on bare ground by the end of March. By the end of the growing season,
medusahead yield was 4 times greater under litter than on bare soil [34].


Moderate temperatures may encourage medusahead growth and yield. Maximum dry matter production of medusahead was
achieved at a moderate day/night temperature regime of 75/52 degrees Fahrenheit (24/11
oC). Its yield was
reduced by 75% with a high day/night temperature regime of 90/61 degrees Fahrenheit (32/16
oC), and reduced by 50% with a
low day/night temperature regime of 61/41degrees Fahrenheit (16/5 oC) [29].

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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Regional Distribution in the Western United States

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More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

BLM PHYSIOGRAPHIC REGIONS [8]:




2 Cascade Mountains

3 Southern Pacific Border

4 Sierra Mountains

6 Upper Basin and Range

8 Northern Rocky Mountains

16 Upper Missouri Basin and Broken Lands
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Successional Status

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More info for the terms: association, climax, forbs, litter

Medusahead occurs in seral and late-successional plant communities. It has invaded vast
areas formerly dominated by perennial
grasses. Medusahead often colonizes
portions of range previously dominated by cheatgrass [27,57]. The growth
habits, life cycles, and ecological adaptations of medusahead and cheatgrass are
similar, and the annuals typically grow in association until medusahead
becomes dominant and eventually exclusive [16]. Southwestern Idaho stands in which medusahead was sparse were all seral. In
virtually all cases studied, the sites invaded by medusahead had been occupied
previously by seral species, mainly annuals, which had replaced perennial
bunchgrasses depleted by overgrazing, fire, or cultivation [64,79,102].
Medusahead has potential
for successionally
replacing cheatgrass in the 11-inch (280 mm) and above precipitation zone in the northern
Great Basin and elsewhere [54]. Medusahead litter impedes cheatgrass establishment, and may do better in low nitrogen environments
than does cheatgrass [50,51]. Coexistence of cheatgrass and medusahead is most likely in habitats
low in both nitrogen and phosphorus. Cheatgrass is likely to have
the competitive advantage in more fertile habitats unless other environmental factors
(e.g. high clay content) favor
medusahead [29]. In the sagebrush steppe of northeastern California,
Russian-thistle (Salsola kali), tumblemustard
(Sisymbrium altissimum), and cheatgrass form a seral continuum that closes many sagebrush
communities to the establishment of perennial seedlings. Medusahead has extended the seral
continuum by replacing cheatgrass on some low sagebrush sites on the Modoc Plateau [118,124].
Cheatgrass usually grows in dense stands
and readily ignites and carries fire. After
fire strikes a cheatgrass-infested community, cheatgrass usually
flourishes. However, medusahead can thrives in the wake of cheatgrass-driven fires
[31].

Medusahead is a seral invader after disturbance [102].
Medusahead often grows in dense stands on disturbed
sites where climax perennial grasses have been removed, often to the exclusion
of other species [51]. The abundance of bluebunch wheatgrass has "significantly" decreased
in the Great Basin because of the invasion of
introduced annuals such as medusahead [81]. Past heavy grazing of
foothills, pastures, and rangelands of southeastern Oregon has resulted in
dominance by annual grasses such as medusahead and annual forbs including
yellow starthistle [15].

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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Taxonomy

provided by Fire Effects Information System Plants
The currently accepted scientific name of medusahead is Taeniatherum caput-medusae
(L.) Nevski. There are 3 subspecies found in Europe: Taeniatherum caput-medusae ssp. caput-medusae,
Taeniatherum caput-medusae ssp. cinitum (Schreb.) Meldris, and
Taeniatherum caput-medusae ssp. asperum (Simk.) Meldris. The
entity occurring the United States is Taeniatherum caput-medusae ssp. asperum [40,53,65].
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Archer, Amy J. 2001. Taeniatherum caput-medusae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/taecap/all.html

Physical Description

provided by USDA PLANTS text
Annuals, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blade auriculate, Leaf blades 2-10 mm wide, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Leaf blades glaucous, blue-green, or grey, or with white glands, Ligule present, Ligul e an unfringed eciliate membrane, Inflorescence terminal, Inflorescence simple spikes, Inflorescence a dense slender spike-like panicle or raceme, branches contracted, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence spike linear or cylindric, several times longer than wide, Inflorescence single raceme, fascicle or spike, Inflorescence spikelets arranged in a terminal bilateral spike, Flowers bisexual, Spikelets sessile or subsessile, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets paired at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the florets, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glume equal to o r longer than spikelet, Glumes displaced, side by side, Glumes awn-like, elongated or subulate, Glume awns divergent, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 5-7 nerved, Lemma glabrous, Lemma rugose, with cross wrinkles, or roughened, Lemma apex acute or acuminate, Lemma distinctly awned, more than 2-3 mm, Lemma with 1 awn, Lemma awn 2-4 cm long or longer, Lemma awned from tip, Lemma awns straight or curved to base, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Palea keels winged, scabrous, or ciliate, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear, Caryopsis hairy at apex.
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USDA PLANTS text

Taeniatherum caput-medusae

provided by wikipedia EN

Taeniatherum is a genus of Eurasian and North African plants in the grass family.[3][4][5]

The only recognized species is medusahead (Taeniatherum caput-medusae) which is native to southern and central Europe (from Portugal to European Russia), North Africa (Algeria, Morocco, Tunisia), and Asia (from Turkey and Saudi Arabia to Pakistan and Kazakhstan).[2][6][7][8][9] It is also naturalized in southern Australia, Chile, and parts of North America.[10][11][12][13]

This aggressive winter annual grass is changing the ecology of western rangelands in North America.[14] It was first observed in the United States in Oregon in 1903 by Thomas Howell. Forty-eight percent of the total land area of the United States is rangeland, pastureland, national parks, nature preserves, and other wildlands. These lands are essential for agriculture and for protecting the integrity of ecological systems. Natural areas contain many nonnative plant species that occur as self-sustaining populations in the continental United States, including medusahead. As of 2005, medusahead infested approximately 972,700 acres (3,936 km2) in the 17 western states (from North Dakota south to Texas and west to the Pacific coast), and spreads at an average rate of 12% per year.[15] As medusahead spreads, it can outcompete native vegetation in overgrazed rangelands, reduces land value, and creates a wildfire hazard.[16]

History and origin

Medusahead was first described Elymus caput-medusae by Carl Linnaeus. Nevski recommended in 1934 that the Russian types of medusahead should be classified in a separate genus, Taeniatherum. In the 1960s, it was suggested by Jack Major of the University of California that there are three geographic and morphologically distinct taxa: T. caput-medusae, T. asperum, and T. crinitum. After traveling in Russia, Major thought the proper classification for the plant introduced to North America was Taeniatherum asperum. The genus was revised in 1986 by the Danish scientist Signe Frederiksen. He made the previously mentioned distinct taxa into subspecies of Taeniatherum caput-medusae.[17]

The subspecies caput-medusae is a native species to Europe, and is mostly restricted to Spain, Portugal, southern France, Algeria, and Morocco. Subspecies crinitum is found from Greece and the Balkans east into Asia, and the range of subspecies asperum completely overlaps the other two subspecies.[17]

In Asia, medusahead is widespread in Turkmenistan, Iran, Syria, and in the northern portion of Israel, inhabiting low mountains and plateau areas. It is both an agronomic and rangeland weed. It prefers soils rich in nitrogen, and is often found on stony or gravelly soils. Carbonized seeds of this weed have been found in early agricultural archaeological sites in Iran. Seeds were first found in strata corresponding to the early days of sheep and goat husbandry.[17]

Life cycle and growing habits

Medusahead is a winter annual, germinating in the fall and undergoing root growth in the winter and early spring. Since its roots develop early and reach deep in the soil, it outcompetes native plants for moisture. It flowers in early spring, and by June or July its seeds, which are covered with tiny barbs, are mature. The barbs help the seeds attach to livestock, humans or vehicles that pass by. As the grass grows it accumulates silica, making it unpalatable to livestock except for early in its life cycle. It creates a dense layer of litter, and because of the silica content, the litter decomposes more slowly than that of other plants. This litter suppresses native plant growth while encouraging the germination of its own seed, and after a few years it creates an enormous load of dry fuel that can lead to wildfires.[14]

Stands of medusahead vary in density from several hundred to 2,000 plants per square foot. This variance is directly related to annual precipitation, soil type, and other vegetation in the area. Research has suggested that medusahead is highly adaptable and can produce more seeds at a density of one plant per square foot than 1,000 plants per square foot.[14] Since it matures later than most other annuals, it is easy to identify as it is often bright green when the other annuals are brown. As it matures, it turns shades of purple and eventually tan.[14] This unique phenological signature can be utilized in the management of this invasive species. A recently developed method of assessing greenness in aerial color infra-red (CIR) imagery using Normalized Difference Vegetation Index (NDVI) values to differentiate between medusahead and other more desirable species may help land managers determine where control methods are necessary.[18]

Medusahead seeds disperse relatively short distances and dispersal decreases as distance from the plant increases. Seeds are very well adapted for dispersal by adhesion to moving objects. The relatively long period of medusahead seed dispersal from July to October may be an adaptation to increase the likelihood of adhesion to animals.[19]

Identification

Medusahead ranges in height from 20 to 60 centimeters.[20] It has slender, weak stems that often branch at the base. It has spike inflorescences similar to those of wheat or rye. The lemmas have long awns and the glumes have shorter ones, giving the seed head a layered look.[21] As the awns dry, they twist and spread in all directions, similar to the snake-covered head of the mythological Medusa. The barbs on the awns help the seed drive into the soil.[22] The grainlike seed may remain viable in the soil for a number of years.[14]

Effects on wildlife and grazing

The grazing capacity of land infested with medusahead can be reduced by up to 80%.[23] Wildlife habitat and biodiversity also suffer, and the weed can eventually lead to alterations in ecosystem functions. The impact medusahead can have on species relying on sagebrush is rarely mentioned. It can exacerbate the decline of sage-grouse (genus Centrocercus) as it replaces plant communities that provide critical habitat for the bird.[23]

Other species, such as mule deer and chukar partridges, tend to avoid areas overrun with medusahead because it is not a good food source. In the case of mule deer, a study in Oregon found that even though extensive stands of medusahead were available, those areas (when compared to other plant communities) were least preferred by feeding mule deer in winter, summer, and fall; and they ranked low in the spring. This decrease in feeding was related back to the dominance of medusahead, which deer do not eat, and the subsequent lack of forbs.[24] Chukar partridges will ingest medusahead seeds (caryopses ) if given no other choice. However, if they are given free access to all the medusahead seeds they will eat, they suffered from a significant loss in body weight. Largely undamaged seeds were found in their droppings, suggesting that the digestibility of medusahead by the birds was low.[25]

Control methods

No single control method will eradicate medusahead. For best results, it is often necessary use a form of integrated pest management that combines two or more of the following methods.

Mechanical

Plowing and disking are two methods of mechanical control. Both methods can effectively control medusahead and can reduce infestation by 65% to 95% the next growing season. Eradication of medusahead by mechanical control by itself is nearly impossible, but when followed by chemical control or revegetation chances for eradication increase dramatically.[14]

Burning

Fire is often considered a low cost method of improving rangeland condition. It has been given attention in the control of medusahead because many of the areas infested with it are too rocky or steep for other treatments. Control of medusahead with fire had differing results in California. In some areas, more desirable plant communities came back after a fire, while in other areas medusahead continued to dominate after fire. There are a few guidelines that should be followed when burning medusahead. The burn should be conducted when the seed is in the soft dough stage (when the seeds exude a milky substance when squeezed) in the late spring. The initial fire should be one that is slow burning, something that is easily achieved by burning into the wind. This prevents the fire from advancing too rapidly and ensures that the current year's herbage is burned and periods of maximum temperature are long enough to kill medusahead caryopses. Viable medusahead caryopses are found almost entirely in the litter and on the soil surface.[26]

Past studies on the effectiveness of burning may have given researchers false hope. The caryopses have severe temperature dependent afterripening requirements which prevent seeds from germinating at temperatures above 10˚C for about 180 days after maturity. If these conditions are met, many medusahead caryopses from the litter and soil in burned plots were viable. Since the seeds did not germinate during the afterripening period, researchers were misled into believing they were accomplishing more by burning than was actually the case.[26]

Chemical

Chemical control can be effective if used in conjunction with other control methods. Glyphosate (Roundup) applied at 0.375 lbs/acre in the early spring before seeds are produced can provide good results. This timing will also limit the damage to nontarget species that develop later in the growing season. Research suggests that burning before chemical application is more effective than chemicals alone.[14] In the late 1960s, a study was conducted that determined the effectiveness of paraquat on medusahead control in different areas of the United States. This study found that paraquat was effective in controlling medusahead in California, but did not suppress the grass in Reno, Nevada. This was significant because it determined that there was no effective herbicide for the simultaneous spraying and reseeding of medusahead infestations.[27]

Biological

Medusahead was found to be susceptible to certain root rot fungi including crown rot and take-all, but it was not susceptible to barepatch, browning root rot, and common root rot. The diseases did not reduce the overall weight of the roots, but take-all significantly reduced the overall dry weight of the aboveground shoots. Soil-borne pathogens can have a severe effect on grasses as long as the environmental conditions for the diseases are optimized. Take-all is associated with plants growing in high soil moisture, and like crown rot, it affected medusahead. In contrast, crown rot had the greatest impact on water-stressed plants and therefore may be an effective biological control of grassy weeds in the arid regions of the western U.S. It is also promising because it did not have a significant negative impact on desirable grasses such as western wheatgrass.[28]

Grazing

Grazing alone is not a good method of medusahead control. For best results, grazing is used as part of an integrated program. It is an efficient management tool as long as the timing and duration of grazing are controlled properly. For example, if grazing is carried out in conjunction with revegetation, the desirable grasses must be established before the grazing can take place, otherwise the revegetation will be futile. In areas where desirable grasses have completed their life cycle by the winter or early spring, grazing during this time can help reduce medusahead. It should still be in a vegetative stage and therefore more palatable to livestock. Grazing in the late spring, summer, and fall is not recommended because it will give medusahead a competitive advantage as cattle graze species other than medusahead. If livestock grazing is a method used to control mature stands of medusahead, the livestock must be moved to a holding area for 10 days to two weeks and fed weed-free feed before they are moved to weed-free areas. This will prevent the seeds that pass through the animals from germinating in areas that are free of medusahead.[14]

Restoration

Revegetation should be a part of any medusahead management plan. If medusahead is not first controlled, reseeding an infested area will not be successful. The existing medusahead has to be controlled and especially not allowed to produce more seed, and the seed bank in the soil also has to be reduced. This usually takes two or three years, depending on soil moisture and growing conditions. After this, seedling of desirable species can become established. Combining a tillage treatment followed by herbicide is most effective in controlling the weed and promoting desirable plant growth. Squirreltail, bluebunch wheatgrass, crested wheatgrass, intermediate wheatgrass, Thurber's needlegrass, needle and thread, Indian ricegrass, sandberg bluegrass, and sheep fescue are all competitive grasses that work well when renovating an area previously infested with medusahead in the western United States.[14]

Prevention

Since medusahead seeds are often spread by adhering to humans, animals, and vehicles, it is recommended to restrict these kinds of traffic in infestations to prevent the spread of medusahead. Narrow containment zones of around 3 meters would successfully suppress the invasion of medusahead to surrounding areas.[19]

Plant communities that have high densities of large perennial bunchgrasses are more resistant to medusahead invasion, so managing rangelands to promote and maintain large perennial bunchgrasses is critical to prevent the spread of medusahead. This will reduce the establishment of new infestations, but successful management will also require searching for and eradicating new infestations. Controlling new infestations is more effective, and often more feasible, than trying to control large infestations.[23]

Even if attempts to prevent and control new infestations are not entirely successful, these efforts will slow the rate of spread and give researchers and land managers more time to develop better prevention, restoration, and control methods. Also, slowing the rate of invasion helps promote rangeland health and productivity in areas that are most at risk of invasion. Without an active prevention program, this weed will continue to spread and increase its negative ecological and economical impacts. Managing medusahead may seem expensive per acre, but when all the acres that are protected by managing an infestation are considered, the price is very reasonable. And, when taking into account the rising land prices, the cost of medusahead management to the individual livestock producer is rapidly becoming more reasonable compared to purchasing additional acreage to offset production losses from medusahead invasion.[23]

References

  1. ^ In: Trudy Sredne-Aziatskogo Gosudarstvennogo Universiteta. Seriya 8b, Botanika 17: 38. 1934. "Name – Taeniatherum Nevski". Tropicos. Saint Louis, Missouri: Missouri Botanical Garden. Retrieved April 15, 2010. Type Specimens: Taeniatherum crinitum (Schreb.) Nevski
  2. ^ a b Kew World Checklist of Selected Plant Families
  3. ^ Nevski, Sergei Arsenjevic. 1934. Trudy Sredne-Aziatskogo Gosudarstvennogo Universiteta. Seriya 8b, Botanika 17: 38
  4. ^ Grassbase – The World Online Grass Flora
  5. ^ Frederiksen, S. 1986. Revision of Taeniatherum (Poaceae). Nordic Journal of Botany 6(4): 389–397
  6. ^ Altervista Flora Italiana genere Taeniatherum
  7. ^ Danin, A. (2004). Distribution Atlas of Plants in the Flora Palaestina area: 1–517. The Israel Academy of Sciences and Humanities, Jerusalem
  8. ^ Cope, T.A., Knees, S.G. & Miller, A.G. (2007). Flora of the Arabian peninsula and Socotra 5(1): 1–387. Edinburgh University Press
  9. ^ Dobignard, D. & Chatelain, C. (2010). Index synonymique de la flore d'Afrique du nord 1: 1–455. Éditions des conservatoire et jardin botaniques, Genève
  10. ^ Biota of North America 2013 county distribution map
  11. ^ Meghan Skaer, 24 Jan 2014, Global Invasions Network, New Kid on the Block: A novel invader in an invaded community
  12. ^ Ausgrass2, Grasses of Australia, Taeniatherum caput-medusae
  13. ^ Zuloaga, F.O., Morrone, O., Belgrano, M.J., Marticorena, C. & Marchesi, E. (eds.) (2008). Catálogo de las Plantas Vasculares del Cono Sur. Monographs in Systematic Botany from the Missouri Botanical Garden 107: 1–3348
  14. ^ a b c d e f g h i Zimmerman, J.R., et al. Medusahead: Economic Impact and Control in Nevada. University of Nevada-Reno Fact Sheet FS-02-37.
  15. ^ Duncan, C.A., et al. (2004). Assessing the economic, environmental, and societal losses from invasive plants on rangeland and wildlands. Weed Technology 18:1411–1416
  16. ^ Dremann, Craig C. Field Notebook No. 260, page 20, Soil samples from the U.C. Sierra Foothill Research & Extension Center, Browns Valley, CA. June 2016
  17. ^ a b c Kostivkovsky, V. and J. A. Young. (2000). Invasive exotic rangeland weeds: A glimpse at some of their native habitats. Rangelands 22:6 3–6.
  18. ^ Malmstrom, C.M., H.S. Butterfield, L. Planck, C.W. Long, and V.T. Eviner. (2017). Novel fine-scale aerial mapping approach quantifies grassland weed cover dynamics and response to management. PLOS ONE 12(10): e0181665.
  19. ^ a b Davies, K. W. (2008). Medusahead dispersal and establishment in sagebrush steppe plant communities. Rangeland Ecology and Management 61: 110–115.
  20. ^ Jepson Manual Treatment
  21. ^ Stubbendieck, J.L., et al. (2004). North American Wildland Plants: A Field Guide. University of Nebraska Press.
  22. ^ US Forest Service Fire Ecology
  23. ^ a b c d Davies, K.W. and D. D. Johnson. (2008). Managing medusahead in the intermountain west is at a critical threshold. Rangelands. 30:13–15
  24. ^ Bodurtha, T.S., et al. (1989). Mule deer habitat use related to succession in a bunchgrass community. Journal of Wildlife Management 53:2 314–319.
  25. ^ Savage, D.E., et al. (1969). Utilization of medusahead and downy brome caryopses by Chukar Partridges. The Journal of Wildlife Management 33:4 975–978.
  26. ^ a b Young, J.A., et al. (1972). Influence of repeated annual burning on a medusahead community. Journal of Range Management 25:5 372–375.
  27. ^ Young, J.A., et al. (1971). Response of medusahead to paraquat. Journal of Range Management 24:1 41–43.
  28. ^ Grey, W.E., et al. (1995). Potential for biological control of downy brome (Bromus tectorum) and medusahead (Taeniatherum caput-medusae) with crown and root rot fungi. Weed Technology 9:2 362–365.

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Taeniatherum caput-medusae: Brief Summary

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Taeniatherum is a genus of Eurasian and North African plants in the grass family.

The only recognized species is medusahead (Taeniatherum caput-medusae) which is native to southern and central Europe (from Portugal to European Russia), North Africa (Algeria, Morocco, Tunisia), and Asia (from Turkey and Saudi Arabia to Pakistan and Kazakhstan). It is also naturalized in southern Australia, Chile, and parts of North America.

This aggressive winter annual grass is changing the ecology of western rangelands in North America. It was first observed in the United States in Oregon in 1903 by Thomas Howell. Forty-eight percent of the total land area of the United States is rangeland, pastureland, national parks, nature preserves, and other wildlands. These lands are essential for agriculture and for protecting the integrity of ecological systems. Natural areas contain many nonnative plant species that occur as self-sustaining populations in the continental United States, including medusahead. As of 2005, medusahead infested approximately 972,700 acres (3,936 km2) in the 17 western states (from North Dakota south to Texas and west to the Pacific coast), and spreads at an average rate of 12% per year. As medusahead spreads, it can outcompete native vegetation in overgrazed rangelands, reduces land value, and creates a wildfire hazard.

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