Regularity: Regularly occurring
Regularity: Regularly occurring
Global Range: Mahonia nervosa ranges from British Columbia, Canada, and south through California, U.S.
Occurrence in North America
Nevada from southern British Columbia through Washington and Oregon to
central California .
Regional Distribution in the Western United States
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
Dwarf Oregon-grape is a low-growing rhizomatous evergreen shrub which
typically reaches 4 to 24 inches in height [28,69]. On exceptional
sites, plants may grow to 7 feet (2.1 m) . The simple stems are
ascending to erect and generally occur in loose colonies of several
stems [69,46,71]. Compound leaves are borne in terminal tufts [66,69].
Coarsely serrate to spinose, ovate to lance-ovate or acute leaflets
occur in groups of 7 to 21 [46,69,95]. Leaflets are dark green, thick,
and leathery [71,95]. Yellow flowers are borne in erect clusters or
racemes up to 8 inches (21 cm) in length [66,69,71]. The fruit is a
large, dark blue, globose berry with grayish or whitish bloom
[28,69,71,95]. Berries are 0.3 to 0.4 inch (8-10 mm) in diameter, occur
in clusters , and contain a number of black seeds .
Catalog Number: US 2853455
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Preparation: Pressed specimen
Collector(s): J. Roof
Year Collected: 1969
Locality: Hardy Creek bank N of Hardy Creek bridge along state highway 1; alt. ca. 100 ft., Mendocino, California, United States, North America
Elevation (m): 30 to 30
- Isotype: Roof, J. B. 1969. Four Seasons. 3 (1): 8.
Comments: An understory plant in western North American coniferous forests, typically growing only on the western side of the Cascades Range below 2200 m. Relatively shade tolerant and common in second-growth Douglas-fir forests (Vance et al in press).
Dwarf Oregon-grape occurs across a wide range of habitats in submontane
to montane forests of the Pacific Northwest [35,54]. It is a
characteristic shrub of spruce-fir forests  but also occurs in
northern coastal coniferous forests and in redwood, mixed evergreen, and
bottomland forests [30,69,78]. In Pacific silver fir communities, dwarf
Oregon-grape is generally restricted to warm, dry sites. In old-growth
Douglas-fir stands of northwestern Oregon, it reaches greatest abundance
on relatively dry sites . This shrub occurs on dry to fairly moist
sites in western hemlock types but reaches greatest abundance on warmer
sites [42,85]. Dwarf Oregon-grape is also common in the warmer
Port-Orford-cedar communities .
Dwarf Oregon-grape commonly grows as scattered, or abundant, individuals
but can dominate the understory of semiopen forests . It frequently
forms "lush carpets" in open meadows bordering coniferous stands 
and commonly persists in coastal brushfields created by timber harvest
[33,43,51]. Dwarf Oregon-grape grows well in sun or shade [54,87].
Plant associates: Common overstory associates in addition to those
mentioned above include Pacific yew (Taxus brevifolia), Sitka spruce
(Picea sitchensis), and tanoak (Lithocarpus densiflora)
[2,31,42,74,84,89]. In spruce-fir forests, dwarf Oregon grape grows
with understory species such as twinflower, rhododendron (Rhododendron
spp.), and queencup beadlily (Clintonia uniflora). Beargrass
(Xerophyllum tenax) occurs on drier sites . Common associates in
Douglas-fir or western hemlock forests include oceanspray, trailing
blackberry (Rubus ursinus), red huckleberry (Vaccinium parvifolium),
Alaska huckleberry, salal, Pacific rhododendron, vine maple, broadleaf
starflower (Trientalis latifolia), and mosses such as Kindbergia oregana
[21,32,44,54,67]. Old-growth stands are often characterized by a
depauperate understory . In redwood (Sequoia sempervirens)
communities, western sword fern, salal, Oregon oxalis, and redwood violet
(Viola sempervirens) are common associates .
Soils: Dwarf Oregon-grape grows well on a variety of soil types 
including coarse, shallow rocky soils, coarse alluvium, or glacial
outwash . Soils are well drained to poorly drained, and dry to
fresh [28,54,70]. Soils are derived from a wide range of parent
material including basalt and metavolcanics, sandstone, siltstone,
diorite, and gabbro [3,7,44,90]. Good growth has been reported on
acidic to moderately alkaline or even somewhat saline soils .
Climate: Dwarf Oregon-grape grows in maritime to submaritime climates.
Growing seasons are fairly long . Some sites experience summer
Elevation: Dwarf Oregon-grape grows at low to middle elevations
[35,90]. In California, it is restricted to sites below 6,000 feet
(1,829 m) .
Key Plant Community Associations
Dwarf Oregon-grape is an understory dominant in montane to submontane
coniferous and mixed evergreen forests of the Pacific Northwest.
Oceanspray (Holodiscus discolor), Alaska huckleberry (Vaccinium
alaskaense), salal (Gaultheria shallon), pachistima (Pachistima
myrsinites), western sword fern (Polystichum munitum), Pacific
rhododendron (Rhododendron macrophyllum), Sadler oak (Quercus
sadleriana), twinflower (Linnaea borealis), deerfoot vanillaleaf (Achyls
triphylla), Oregon oxalis (Oxalis oregana), and vine maple (Acer
circinatum) occur as codominants within the forest understory. Dwarf
Oregon-grape is listed as an indicator or dominant in the following
Forest types of the North Cascades National Park Service Complex 
The tanoak series of the Siskiyou region of southwest Oregon (Part 2) 
Preliminary plant associations of the Siskiyou Mountain Province 
Plant association and management guide for the Pacific silver fir zone:
Gifford Pinchot National Forest 
Natural vegetation of Oregon and Washington 
Understory development in Pseudotsuga forests: multiple paths of
Forest succession on alluvial landforms of the MacKenzie River Valley,
Plant communities in the old-growth forests of north coastal Oregon 
Forest ecosystems of Mount Rainier National Park 
Mixed evergreen forest .
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):
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir - spruce
FRES24 Hemlock - Sitka spruce
FRES28 Western hardwoods
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
207 Red fir
211 White fir
213 Grand fir
215 Western white pine
221 Red alder
224 Western hemlock
225 Western hemlock - Sitka spruce
226 Coastal true fir - hemlock
227 Western redcedar - western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir - western hemlock
231 Port-Orford cedar
233 Oregon white oak
234 Douglas-fir - tanoak - Pacific madrone
244 Pacific ponderosa - Douglas-fir
246 California black oak
247 Jeffrey pine
249 Canyon live oak
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K002 Cedar - hemlock - Douglas-fir forest
K003 Silver fir - Douglas-fir forest
K005 Mixed conifer forest
K006 Redwood forest
K007 Red fir forest
K013 Cedar - hemlock - pine forest
K026 Oregon oakwoods
K029 California mixed evergreen forest
K030 California oakwoods
Berries and leaves are browsed by ungulates and rodents (Tilford1998). Also, provides significant forage for the white-footed vole in coastal Oregon (Vance et al. in press). This plant aerates and stabilizes soils.
Fire Management Implications
Dwarf Oregon-grape and others shrubs are more likely to dominate early
seral stages after fires of low intensity. Damage or destruction of
underground regenerative structures is more probable after severe fires
and can result in a slow recovery. Shrubs in general are less severely
harmed by fires in early spring or late fall when carbohydrate reserves
are still concentrated in the roots than by fires occurring during
Parent materials - bedrock was composed of quartz diorite and diorite,
overlain with glacial till, outwash, and minor
lacustrine and aeolian deposits.
Soils - mixture of colluvium, loess, and ablation till; loamy with mixed
Climate - marine and cool. no distinct dry season.
average of 203 frost-frees days per year.
Fire Management Considerations
Timber harvest: Dwarf Oregon-grape commonly exhibits dramatic
reductions soon after timber harvest and subsequent slash fires in
western hemlock-western redcedar-Douglas-fir forests of the Cascade
Ranges, but then often undergoes a dramatic recovery . In some
areas, dwarf Oregon-grape cover has tripled during the first 5 years
after logging and slash fires . However, initial recovery may be
fairly slow on some sites . Posttreatment cover is presumably
related to a number of factors including fire intensity and severity,
season of fire, and site characteristics. Dwarf Oregon-grape commonly
reaches greatest abundance during secondary succession . Abundance
peaked at 30 to 40 years after clearcutting, broadcast burning, and
planting in western hemlock-Douglas-fir forests of the western Cascades
. Posttreatment recovery was as follows :
years since treatment
2 5 10 15 20 30 40 undisturbed old growth
1.88 5.04 4.22 9.48 6.98 22.18 20.97 11.52
Posttreatment response of dwarf Oregon-grape has been documented in a
number of other studies [7,16,17,27,79,91].
Fuels: Many dwarf Oregon-grape communities are characterized by low to
medium fuel levels .
Prescribed fire: Prescribed fire in Pacific rhododendron-dwarf
Oregon-grape communities can greatly increase herb and shrub production
Broad-scale Impacts of Plant Response to Fire
Cascades National Park was as follows :
1971 1972 1974
freq. cover freq. cover freq. cover
site 1 44 -- 40 .1 32 .6
site 2 82.6 1.6 82.6 2.3 82.6 3.4
site 3 90.3 .16 83.9 2.2 83.9 4.9.
Plant Response to Fire
Dwarf Oregon-grape often sprouts from underground rhizomes after
aboveground portions of the plant are killed [74,91]. However, response
varies with fire intensity, severity [33,58], and season. Atzet and
Wheeler  noted sprouts after light-severity fires but did not observe
sprouting after moderate-severity fires. Seedling establishment after
fire has not been documented  and may be insignificant.
Postfire recovery: Postfire reestablishment and growth of dwarf
Oregon-grape is often rapid . In western Washington, sprouts are
commonly observed soon after fire . Under some circumstances cover
may equal or exceed that of prefire levels within several years .
Dwarf Oregon-grape cover 9 years after slash burning near Oakridge,
Oregon, surpassed that of adjacent unburned plots .
Dwarf Oregon-grape abundance may not peak until mid- to late seral
stages, particularly after hot fires . Recovery can be slow after
moderate to hot fires that damage or kill portions of underground
rhizomes. Few dwarf Oregon-grape were present by the third growing
season after a moderate fire in coastal British Columbia .
long fire-free intervals. However, as a residual survivor, it is also
well-adapted to a regime of "relatively frequent surface fires" such as
those common in certain Douglas-fir-western hemlock/dwarf Oregon-grape
types of Oregon . Fire intervals in Douglas-fir-western hemlock
forest inhabited by dwarf Oregon-grape commonly range from 137 to 320
years [1,71]. Fire intervals in other forest types occupied by dwarf
Oregon-grape have been estimated as follows in Desolation Peaks,
ponderosa pine-Douglas-fir 52 years
lodgepole pine-Douglas-fir 76 years
Douglas-fir-grand fir 93 years
Douglas-fir-Pacific silver fir 108 years
Fire can produce gaps in old-growth redwood forests which are conducive
to dwarf Oregon-grape growth .
Dwarf Oregon-grape commonly sprouts and grows vigorously after fire .
Reestablishment through seed may occur, although vegetative regeneration
is the dominant mode of postfire establishment .
More info for the terms: climax, cover, eruption, succession
Dwarf Oregon-grape is an important component of both seral and climax
communities of the Pacific Northwest. It occurs in recent clearcuts as
well as in stands 300 to 600 years or older [20,82]. It is a woody
survivor or residual colonizer, generally increasing dramatically after
low intensity disturbances such as light fires [32,91]. It commonly
persists on cutover  or lightly burned sites. Residual survivors
sprouted soon after the eruption of Mount St. Helens  and were
particularly evident in protected microsites such as near the bases or
rootwads of trees. The intensity of disturbance, and of fires in
particular, exerts a great influence on dwarf Oregon-grape [33,58]. In
many areas, it codominates a site soon after light-severity disturbance
but may decline in early seral stages when it is overtopped by rapidly
growing conifer seedlings [33,49].
Annuals and weedy invaders commonly dominate early seral stages where
disturbance has been intense . Fireweed and wood groundsel (Senecio
sylvaticus) assume dominance during the first 1 to 3 years on many
intensely disturbed sites . Perennials such as dwarf Oregon-grape
may not become prominent on intensely burned sites until midsuccessional
stages. In some areas, 30 to 40 years or more may be required before
maximum abundance of dwarf Oregon-grape is reached . It does not
attain maximum cover until later seral stages in many western
redcedar-western hemlock-Douglas-fir forests of thge Cascade Ranges of
Oregon and Washington [18,49].
Dwarf Oregon-grape can assume importance in shrub-dominated stages which
develop 4 to 5 years after disturbance in western hemlock forests of the
Pacific Northwest , and can achieve peak abundance within 5 to 10
years after fire in many parts of this region . In the central
Oregon Coast Ranges, is exhibits rapid regrowth and shares understory
dominance in 7- to 50-year-old forests .
Dwarf Oregon-grape is tolerant of shade and can complete its life cycle
even in dense forests of the Pacific Northwest . In the Coast
Ranges of central Oregon, it dominates many old-growth western
hemlock-western redcedar forest understories . It is also an
important component of many climatic or topoedaphic climax western
hemlock communities [4,38,39]. Many seral Douglas-fir/dwarf
Oregon-grape communities ultimately give rise to climax western hemlock
types [38,39] as Douglas-fir declines late in succession . Late
seral Douglas-fir/vine maple-dwarf Oregon-grape communities become
climax western hemlock-Pacific rhododendron-dwarf Oregon-grape
Dwarf Oregon-grape can reproduce from seed or by vegetative means.
Seed: Seed of most Oregon-grapes exhibit internal dormancy and require
cold stratification for germination. However, in certain laboratory
tests, dwarf Oregon-grape seed did not germinate after 90 days of cold
stratification . Results of other studies indicate that seed will
germinate if sown immediately or if stratified and planted in the spring
. Maximum germination capacity in laboratory tests was estimated at
77 percent . Under natural conditions, seeds of most species within
the genus germinate during the spring . The role of sexual
reproduction on disturbed sites is poorly known .
Vegetative regeneration: Dwarf Oregon-grape is rhizomatous  and
gradually expands laterally in the absence of disturbance. Layering has
also been reported . Plants generally sprout from rhizomes or
"creeping rootstocks" after aboveground portions of the plant are
destroyed [47,74,87,91]. Vegetative regeneration appears to be the
dominant mode of regeneration after fire or other disturbances .
Growth Form (according to Raunkiær Life-form classification)
Immediate Effect of Fire
fires . Underground regenerative structures often survive even if
aboveground portions are consumed by fire [74,91].
Plot 7 - September 9, 1968/moderate
Life History and Behavior
Plants flower in early to late spring. Fruit ripens during July and
August . Generalized flowering and fruiting dates are as follows
location flowering fruit ripe
Northwest March-June --
CA April-June --
OR (300 ft [91 m]) early April mid-August
OR (3,250 ft [991 m]) mid-May late August
w OR, sw WA March-June --
WA May September
Molecular Biology and Genetics
Statistics of barcoding coverage: Mahonia nervosa
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
Statistics of barcoding coverage: Berberis nervosa
Public Records: 0
Specimens with Barcodes: 3
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Rounded National Status Rank: NNR - Unranked
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Mahonia nervosa ranges from British Columbia south through California in coniferous forests typically only on the western side of the Cascades Range. It is relatively abundant throughout its range. This species is traded in the medicinal, herbal, and landscaping markets, but to a lesser degree than Mahonia aquifolium, because its roots are relatively smaller. However, it may be threatened by increased demand as it is considered to be interchangeable with Mahonia aquifolium by some sources familiar with the medicinal plants industry.
Comments: Mahonia species are reportedly used as a substitute for goldenseal (Tilford 1998). Some experts in the medicinal plant industry have suggested that trade is medium to large and demand has increased over the past ten years (Robbins 1999). Thus, although current demand is modest, increased interest is possible. Therefore, trends in commercial interest and collecting activities should be monitored even though it is relatively common in its native range. This species is traded in the medicinal, herbal, and landscaping markets, however it may be less viable for large-scale commercial harvest than Mahonia aquifolium because its roots are relatively smaller (Vance et al. in press). Disturbance reduces this species' ability to spread through rhizomes (Vance et al. in press). See Vance et al. (in press) for suggested guidelines for sustainable harvesting techniques.
Timber harvest: Dwarf Oregon-grape commonly persists on cutover sites
[54,58]. In many parts of British Columbia and the Pacific Northwest, it
assumes prominence in brushfields made up of such species as salal,
bracken fern (Pteridium aquilinum), blackberries and raspberries (Rubus
spp.), fireweed (Epilobium angustifolium), huckleberries (Vaccinium
spp.), and willows (Salix spp.) [43,54]. Brushfield species may compete
with conifer regeneration in some locations .
Biomass: The green weight of dwarf Oregon-grape has been estimated at
130 pounds per acre (145 kg/ha) in certain western hemlock types of
Grazing: Grazing by domestic sheep apparently has little effect on
dwarf Oregon-grape .
Chemical control: Percent frequency following herbicide applications
combined with mechanical treatment or fire in central coastal Oregon was
as follows :
glyphosate spray and burn spray and crush
pretreatment 13 13 9
posttreatment -- 3 --
The effects of various herbicides on Berberis spp. have been considered
in detail .
Relevance to Humans and Ecosystems
Uses: MEDICINE/DRUG, LANDSCAPING
Production Methods: Cultivated, Wild-harvested
Value for rehabilitation of disturbed sites
or stem cuttings [15,75,80]. However, plants may be slow to establish
. Detailed information on propagation techniques is available
Dwarf Oregon-grape presumably provides cover for small birds and
mammals. The diverse structure of western hemlock/dwarf
Oregon-grape-salal types provides good big game hiding cover .
Pacific silver fir/dwarf Oregon-grape and western hemlock/dwarf
Oregon-grape-Oregon oxalis communities offer good thermal cover for deer
and elk [41,43].
documented as follows :
average percent by weight -
N P Mg Ca Na K
stem .44 .10 .05 .29 .0040 .51
foliage .85 .12 .09 .24 .0020 .87
Nutrient content of fruit is listed below [70,94]:
nutrient content per gram dry weight
kjoule cal. protein carbo. ash lipid Ca Fe Mg Zn
x 1,000 (g) (g) (g) (g) (mg) (mg) (mg) (mg)
15.86 3.79 0.18 0.71 0.04 0.08 1.91 0.03 0.85 0.05
carbo. fat ash N P K Ca Mg Na
(percent dry weight)
78.0 1.70 7.40 1.60 0.50 2.70 0.20 0.30 0
Importance to Livestock and Wildlife
In many parts of the Pacific Northwest, Douglas-fir-western
hemlock/dwarf Oregon-grape and western hemlock/dwarf Oregon-grape-salal
habitat types provide important big game wintering areas [43,85].
Stands often offer good structural diversity and remain relatively
snow-free . However, where dense shrub thickets develop, big game
use may be limited . Western hemlock/dwarf Oregon-grape-Oregon
oxalis and western hemlock/dwarf Oregon-grape-deerfoot vanillaleaf types
serve as big game summer range .
Browse: In some areas, dwarf Oregon-grape is browsed by black-tailed
deer [12,87]. In other locations it is seldom used . Harcombe 
reported moderate use of dwarf Oregon-grape by Roosevelt elk during
winter but not in the spring or summer . Various small mammals feed
extensively on the foliage. It is, for example, an extremely important
dietary component of the white-footed vole in the Coast Ranges of Oregon
. Dwarf Oregon-grape comprised 32 percent of the vole's diet in
February but declined to 17 percent by June. The value of dwarf
Oregon-grape browse to domestic livestock is apparently low in most
locations. Utilization by domestic sheep in the Cascade Ranges in
Washington may reach 6.8 to 23.7 percent . The fruits are readily
eaten by many small birds  and mammals. In some areas, black-tailed
deer also eat the fruits . The nectar of several species within the
genus Berberis is favored by the Anna's hummingbird .
Other uses and values
the Pacific Northwest traditionally ate the fruits and made medicinal
teas from the boiled roots [35,70]. Dyes for baskets were also obtained
from the roots .
Dwarf Oregon-grape is a popular ornamental. It is well suited for shady
locations and is widely planted in gardens throughout the Pacific
Northwest. Its attractive foliage and short stature make it a
particularly effective border plant . Although it multiplies well
under cultivation, it does not form dense thickets. Foliage often turns
a striking reddish-purple in winter after exposure to cold temperatures
Mahonia nervosa, commonly known as dwarf Oregon-grape, Cascade Oregon-grape, or dull Oregon-grape, is a flowering plant native to the northwest coast of North America from southern British Columbia south to central California, with an isolated population inland in northern Idaho. It is especially common in second growth, Douglas-fir or western redcedar forests, making use of those pools of sunlight that intermittently reach the ground.
It is an evergreen shrub with short vertical stems, mostly under 30 cm (12 in), while the leaves reach higher, rarely up to 2 m (6 ft 7 in) tall. The leaves are compound, with 9-19 leaflets; each leaflet is strongly toothed, reminiscent of holly, and somewhat shiny, but less so than tall Oregon-grape. The leaflets do not have a single central vein as in that species, but several veins arranged fan-like, branched from the leaflet base, hence the epithet nervosa. The flowers and fruit are like those of other Oregon-grapes, and are equally bitter-tasting.
- Roof, James B. Four Seasons 3(1): 8–10, f. s.n. [p. 9, upper right]. 1969.
- Roof, James B. Changing Seasons 1(3, Suppl.): 14. 1981.
- Hickman, J. C. 1993. The Jepson Manual: Higher Plants of California 1–1400. University of California Press, Berkeley.
- Munz, P. A. & D. D. Keck. 1959. California Flora 1–1681. University of California Press, Berkeley.
- Hitchcock, C. H., A.J. Cronquist, F. M. Ownbey & J. W. Thompson. 1984. Salicaceae to Saxifragaceae. Part II: 1–597. In C. L. Hitchcock et al. Vascular Plants of the Pacific Northwest. University of Washington Press, Seattle.
- Pojar, Jim; MacKinnon, Andy, eds. (1994). Plants of Coastal British Columbia: including Washington, Oregon & Alaska, rev. ed. Vancouver: Lone Pine Publishing. p. 95. ISBN 978-1-55105-532-9.
- Loconte, H., & J. R. Estes. 1989. Phylogenetic systematics of Berberidaceae and Ranunculales (Magnoliidae). Systematic Botany 14:565-579.
- Marroquín, Jorge S., & Joseph E. Laferrière. 1997. Transfer of specific and infraspecific taxa from Mahonia to Berberis. Journal of the Arizona-Nevada Academy of Science 30(1):53-55.
- Laferrière, Joseph E. 1997. Transfer of specific and infraspecific taxa from Mahonia to Berberis. Bot. Zhurn. 82(9):96-99.
- Fl. Amer. Sept. (Pursh) 219. 1814 [Dec. 1813]. Collectors: M.Lewis, W.Clark s.n. "Plant Name Details for Berberis nervosa". IPNI. Retrieved November 27, 2009.
- GRIN (November 10, 2005). "Berberis nervosa information from NPGS/GRIN". Taxonomy for Plants. National Germplasm Resources Laboratory, Beltsville, Maryland: USDA, ARS, National Genetic Resources Program. Retrieved November 27, 2009.
- Hunn, Eugene S. (1990). Nch'i-Wana, "The Big River": Mid-Columbia Indians and Their Land. University of Washington Press. p. 352. ISBN 0-295-97119-3.
Berberis nervosa is resistant to infection by Puccinia graminis .
The Skagit tribe used Berberis nervosa medicinally in a root preparation to treat venereal disease (D. E. Moermann 1986).
Names and Taxonomy
Comments: Varieties in Mahonia nervosa are not recognized by Kartesz (1999); in 1994, he had recognized vars. mendocinensis and nervosa. These plants have also been treated in the genus Berberis. LEM 18Feb01.
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