Agrostis exarata Trin.

spike bentgrass
spike redtop
spike bent
western bentgrass

Spike bentgrass is a native, perennial bunchgrass. Culms are slender
and erect, usually 3.3 to 5 feet (1-1.5 m) tall [1,11,20,24]. The
blades are ascending to spreading, 0.08 to 0.4 inch (2-10 mm) wide, and
up to 8 inches (20 cm) long [9,11,16]. The panicle is narrow, open to
spikelike, and 4 to 10 inches (10-25 cm) tall [1,9]. Spike bentgrass
occasionally develops slender rhizomes [11,16].

Spike bentgrass is mostly a western grass. It occurs from Manitoba,
South Dakota, Nebraska, Texas, and Mexico west to the Pacific states and
provinces, including Alaska [8,12,18]. Spike bentgrass is widely
distributed in the mountains of northern California and occurs on Santa
Cruz Island, off the coast of southern California [5]. Zifka [30]
discovered an adventive colony of spike bentgrass (Agrostis exarta var.
monolepis) in Rutland County, Vermont, in 1982.

More info for the term: fire regime

No information was available in the literature concerning spike
bentgrass fire ecology or adaptations. However, a similar species,
ticklegrass (Agrostis scabra), colonizes bare mineral soil on recently
burned sites and may store seeds in the soil for short durations,
allowing for early establishment of areas burned in the spring (see the
FEIS write-up for Agrostis scabra).

FIRE REGIMES :
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".

Since spike bentgrass is considered a decreaser species when overgrazed
[21], fire plans may have to be coordinated with grazing management to
ensure seedling establishment.

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More info for the term: hemicryptophyte

Hemicryptophyte

More info for the term: forest

Spike bentgrass occurs in a wide variety of habitats including
woodlands, forest openings, grasslands, shrublands, meadows, marshes,
and stream and lake margins [9,18,24,29]. It is most commonly found in
moist open places [1,12,20] but is also found in dry habitats such as
semiarid grasslands [10,19]. Spike bentgrass grows on disturbed sites
such as ditches and along roadsides [11,30]. Spike bentgrass occurs
from sea level to alpine zones [5,10,18,20,29]. It occupies sites as
high as 10,500 feet (3,150 m) in Utah [29].

Spike bentgrass grows well on soils derived from schists, limestones,
sandstones, and conglomerates [32].

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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):

42 Bur oak
201 White spruce
203 Balsam poplar
206 Engelmann spruce - subalpine fir
209 Bristlecone pine
210 Interior Douglas-fir
216 Blue spruce
217 Aspen
218 Lodgepole pine
219 Limber pine
222 Black cottonwood - willow
233 Oregon white oak
235 Cottonwood - willow
237 Interior ponderosa pine
238 Western juniper
239 Pinyon - juniper
250 Blue oak - Digger pine
252 Paper birch
256 California mixed subalpine

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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

FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES23 Fir - spruce
FRES26 Lodgepole pine
FRES28 Western hardwoods
FRES29 Sagebrush
FRES34 Chaparral - mountain shrub
FRES35 Pinyon - juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES41 Wet grasslands
FRES44 Alpine

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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 terms: forest, shrub, woodland

K002 Cedar - hemlock - Douglas-fir forest
K005 Mixed conifer forest
K008 Lodgepole pine - subalpine forest
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K015 Western spruce - fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine - Douglas-fir forest
K020 Spruce - fir - Douglas-fir forest
K022 Great Basin pine forest
K023 Juniper - pinyon woodland
K024 Juniper steppe woodland
K026 Oregon oakwoods
K030 California oakwoods
K033 Chaparral
K035 Coastal sagebrush
K047 Fescue - oatgrass
K049 Tule marshes
K051 Wheatgrass - bluegrass
K052 Alpine meadows and barren
K055 Sagebrush steppe
K056 Wheatgrass - needlegrass shrubsteppe
K063 Foothills prairie
K064 Grama - needlegrass - wheatgrass
K065 Grama - buffalograss
K066 Wheatgrass - needlegrass
K068 Wheatgrass - grama - buffalograss

Grasses are generally top-killed by fire so spike bentgrass is probably
top-killed by fire. Specific fire effects, however, are not described
in the literature.

Spike bentgrass is an important source of montane forage for livestock
in the summer [24,27,29,32]. Herbage stays green and palatable
throughout the summer [24,27,29].

More info for the terms: association, forest, grassland, tree, tundra

Spike bentgrass occurs in a wide variety of habitat types including
pinyon-juniper (Pinus-Juniperus spp.), aspen (Populus spp.), fir-spruce
(Abies-Picea spp.), ponderosa pine (Pinus ponderosa), lodgepole pine (P.
contorta), subalpine forest, coastal sage scrub, meadow, alpine, and
tundra [3,5,19,27,28].

In Utah, spike bentgrass is a common grass in wet meadows and parklands
in mountain grassland communities and moist, semishaded sites in aspen
communities. It is also is found in sagebrush (Artemisia spp.)
communities [29].

In the Black Hills of western South Dakota, spike bentgrass is a common
understory species in quaking aspen (Populus tremuloides) communities
[32].

In northwestern Oregon, spike bentgrass is a component of the
Douglas-fir (Pseudotsuga menziesii) forest [17].

Along montane forest river valleys in Colorado, spike bentgrass occurs
in cottonwood-willow (Populus-Salix spp.) and red-osier dogwood (Cornus
sericea) associations [2].

Spike bentgrass is a member of the pink mountain heather-white mountain
heather (Phyllodoce empetriformis-Cassiope mertensiana) meadow community
in northwestern Washington [3].

In the annual grasslands of California, spike bentgrass is a member of
the fescue-oatgrass (Festuca-Danthonia) community [10]. In southern
California, it is also a member of coastal sage scrub, particularly the
purple sage (Salvia leucophylla) association [28].

Spike bentgrass occurs in tundra on the northeastern arctic slope of
Alaska [19].

The following publication lists spike bentgrass as a community dominant:

The chaparral vegetation of Santa Cruz Island, California [5]

Species not previously mentioned but commonly associated with spike
bentgrass in the Rocky Mountain states include American hazel (Corylus
americana), thinleaf alder (Alnus incana ssp. tenuifolia), Rocky
Mountain maple (Acer glabrum), common chokecherry (Prunus virginiana),
Saskatoon serviceberry (Amelanchier alnifolia), shinyleaf spiraea
(Spiraea lucida), silver buffaloberry (Shepherdia argentea), Kentucky
bluegrass (Poa pratense), bluejoint reedgrass (Calamagrostis
canadensis), beaked sedge (Carex rostrata), water sedge (C. aquatilis),
field horsetail (Equisetum arvense), hairy willowweed (Epilobium
ciliatum), Richardson geranium (Geranium richardsonii), smooth aster
(Aster laevis), cream peavine (Lathyrus ochroleucus), wild sarsaparilla
(Aralia nudicaulis), white clover (Trifolium repens), and
false-Solomon's-seal (Smilacina stellata) [2,32].

Species not previously mentioned but commonly associated with spike
bentgrass in California include California scrub oak (Quercus dumosa),
chamise (Adenostoma fasciculatum), toyon (Heteromeles arbutifolia),
hollyleaf cherry (Prunus ilicifolia), sugar sumac (Rhus ovata), tree
poppy (Dendromecon rigida), coyote brush (Baccharis pilularis), Catalina
bedstraw (Galium catalinense), southern bush monkeyflower (Mimulus
longiflorus), tufted hairgrass (Deschampsia cespitosa), nodding trisetum
(Trisetum cernuum), Geyer oniongrass (Melica geyeri), soft chess (Bromus
mollis), red brome (B. rubens), wild oat (Avena fatua), foxtail barley
(Critestion jubatum), naked sedge (Calamagrostis nutkaensis), and
prairie junegrass (Koeleria macrantha) [5,10].

More info for the term: graminoid

Graminoid

More info for the terms: climax, cover, fuel

Spike bentgrass is considered the most valuable native redtop (Agrostis
spp.) on California rangelands because of its abundance and wide
distribution [24]. Spike bentgrass decreases with overgrazing in climax
meadows of the Sierra Nevada [21].

In the spring of 1972, there was a spill of diesel fuel in a subalpine
meadow on Mount Baker, Washington. The estimated prespill cover of
spike bentgrass was minute. All plants were killed by the diesel fuel.
Spike bentgrass was not found in a survey of the area conducted in 1980
[3].

AK AZ CA CO ID HI MT NE NV NM
OK OR SD TX UT VT WA WY AB BC
MB SK MEXICO

Spike bentgrass is rated good for cattle, horses, and elk, and fair to
good for sheep and deer [29].

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More info for the term: seed

Spike bentgrass flowers from June to August [16,20]. Seed ripens and
sheds during August and September, depending on altitude [24].

No specific information on spike bentgrass response to fire is available
in the literature. Ticklegrass, a similar species, increases in
abundance in response to fire (see the FEIS write-up for Agrostis
scabra).

More info for the term: graminoid

Tussock graminoid
Initial-offsite colonizer (off-site, initial community)

More info for the term: seed

Spike bentgrass reproduces primarily by seed but may also spread
laterally by rhizomes [11,24]. Seeds colonize recently disturbed sites
that have exposed mineral soil seedbeds [13].

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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):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

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More info for the terms: climax, seed

Facultative Seral Species

Spike bentgrass is generally a pioneer species. It is relatively shade
intolerant and thrives in open, sunny locations [13]. Seed becomes
established on bare mineral soil. Seedlings of spike bentgrass become
established on old-growth forests that have been recently harvested
[13]. Once spike bentgrass becomes established, it may remain important
throughout the early seral stages [13]. Spike bentgrass is a component
of relatively undisturbed riparian communities in Colorado [2]. In the
Sierra Nevada, spike bentgrass may occur in climax meadow vegetation
[21].

The currently accepted scientific name of spike bentgrass is Agrostis
exarata Trin. [1,9,11,20,27]. It is a member of the Poaceae family.
There are three recognized varieties:

A. e. var. exarata
A. e. var. pacifica Vasey [14,20]
A. e. var. monolepis (Torrey) Hitchc. [11,20,27]

Spike bentgrass apparently hybridizes with ticklegrass (A. scabra) and
bentgrass (A. stolonifera) [27].

Spike bentgrass has been used as a soil stabilizer in degraded areas
[27].