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SPECIES: Grayia spinosa
Tirmenstein, D. A. 1999. Grayia spinosa.
In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
No special status
Spiny hopsage grows east of the Cascade Range and Sierra Nevada from central Washington to southern California, eastward to southwestern Montana and western Colorado [6,23,54]. It is scattered throughout the Great Basin and northern Mojave Desert .
FRES21 Ponderosa pine
FRES30 Desert shrub
FRES40 Desert grasslands
AZ CA CO ID MT NM NV OR UT WA WY
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
K017 Black Hills pine forest
K023 Juniper-pinyon woodland
K037 Mountain mahogany-oak shrub
K038 Great Basin sagebrush
K041 Creosote bush
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe
K057 Galleta-threeawn shrubsteppe
K063 Foothills prairie
237 Interior ponderosa pine
107 Western juniper/big sagebrush/bluebunch wheatgrass
211 Creosotebush scrub
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
316 Big sagebrush-rough fescue
320 Black sagebrush-bluebunch wheatgrass
321 Black sagebrush-Idaho fescue
408 Other sagebrush types
414 Salt desert shrub
Spiny hopsage is well adapted to sagebrush deserts, juniper-pinyon (Pinus-Juniperus spp.) woodlands, and salt desert shrublands [6,8]. It grows in association with such species as ponderosa pine (P. ponderosa), Utah juniper (J. osteosperma), and singleleaf pinyon (P. monophylla) . Spiny hopsage commonly occurs in fairly pure stands  or in large extensive tracts with big sagebrush (Artemisia tridentata) . Spiny hopsage often grows in association with budsage (A. spinescens), black greasewood (Sarcobatus vermiculatus), fourwing saltbush (Atriplex canescens), Gardner's saltbush (A. gardneri), winterfat (Krascheninnikovia lanata), creosotebush (Larrea tridentata), horsebrush (Tetradymia spp.), green rabbitbrush (Chrysothamnus viscidiflorus), galleta (Hilaria jamesii), needle-and-thread grass (Hesperostipa comata), and Sandberg bluegrass (Poa secunda) [6,15,80].
Spiny hopsage is dominant in a number of desert shrub communities. It is often codominant with big sagebrush, black sagebrush (Artemisia nova), green rabbitbrush, shadscale (Atriplex confertifolia), and Sandberg bluegrass [2,5,9]. Publications describing spiny hopsage as a dominant or indicator species include:
Presettlement vegetation of part of northwestern Moffat County, Colorado, described from remnants 
Vegetation and soils of the Cow Creek Watershed 
Vegetation and soils of the Churchill Canyon Watershed 
Steppe vegetation of Washington 
Vegetation and plant communities of southern California deserts--a functional view 
Sagebrush steppe 
Spiny hopsage is tolerant of grazing and where abundant is a valuable browse plant for many species of wildlife and livestock [6,9,45,67]. Spiny hopsage provides a palatable and nutritious food source for big game and livestock, particularly during late winter through spring . Its relative forage value may be less during the fall when it has been described as "useless." However, Stubbendieck and others  describe spiny hopsage as being browsed by livestock in the fall, winter, and spring. Spiny hopsage is used as forage to at least some extent by domestic sheep and goats, deer, pronghorn, and rabbits .
On bighorn sheep ranges in east-central Idaho, Lauer and Peek  reported heavy use of spiny hopsage. It receives at least some winter pronghorn use in Utah . Spiny hopsage provides food for the mountain cottontail in south-central Idaho . In northeastern California, spiny hopsage is a major food of the black-tailed jackrabbit . Spiny hopsage seedlings are eaten by a variety of small mammals including Botta's pocket gopher, Merriam's kangaroo rat, southern grasshopper mouse, deer mouse, and desert cottontail .
Spiny hopsage provides browse for domestic sheep in parts of Wyoming  and is described as a ?good? forage species for domestic sheep in Utah. Domestic sheep browse the succulent new growth in late winter and early spring [25,26]. In north-central Wyoming, spiny hopsage occurs with greasewood and winterfat and provides forage for winter livestock . In Utah, spiny hopsage is important in the diet of domestic sheep only during early spring . In the Mojave Desert, domestic sheep browse spiny hopsage late in the growing season . The large quantities of seeds produced are valuable for fattening domestic sheep . Minor damage to livestock may result from the spines [6,67].
Van Dyke and others  reported moderate fall use of spiny hopsage by bighorn sheep in southeastern Oregon.
Spiny hopsage is considered one of the most palatable of the salt desert shrubs, particularly during the spring. However, overall value is limited in most areas since leaves and fruits are shed by early summer . Early spring growth is very palatable, but by mid-summer palatability is very poor.
Spiny hopsage retains very little edible forage over the fall and winter . However, Wasser  reports fair to good palatability for deer and domestic sheep and goats in the late fall, winter, and spring. Palatability to cattle is described as ?fair to poor? and palatability to horses is rated as ?poor to useless? . The degree of preference shown by browsing animals apparently varies greatly according to ecotypic variability by stand . Thorns may keep spiny hopsage from being utilized [6,67].
The degree of use shown by livestock and wildlife species for spiny hopsage in several western states is rated as follows :
CO OR UT WY Cattle Fair ____ Fair Fair Domestic sheep Good ____ Good Good Horses Fair ____ Good Good Pronghorn ____ ____ Fair Fair Bighorn ____ Fair ____ ____ Elk ____ ____ Fair ____ Mule deer ____ ____ Fair Poor White-tailed deer Poor ____ ____ ____ Small mammals Fair ____ Good Good Small nongame birds ____ ____ Poor ____ Upland game birds ____ ____ Fair ____ Waterfowl ____ ____ Poor ____
Spiny hopsage is rated "fair" in energy and protein value . In southwestern Idaho, crude protein of foliage averages 18% during late winter and 11.8% in the summer months . Nutritional content of spiny hopsage, expressed as a percentage of dry matter, is as follows :
Aerial Part, Aerial Part, Pods, Fresh Leaves, Fresh Dormant Ash (%) 5.1 30.0 23.0 Crude Fiber (%) 38.3 9.2 22.2 Ether Extract (%) 2.0 1.7 1.2 N-Free Extract (%) 45.7 48.3 44.8 Protein (N ? 6.25) (%) 8.9 10.2 8.8 cattle: digestible protein (%) 5.5 6.2 5.0 cheep: digestible protein (%) 5.3 6.5 5.2 Phosphorus % 0.19 --- ---The following nutritional values have been reported for spiny hopsage in the northern Mojave Desert :
N(%) P(%) Na(%) K(%) Ca(%) Mg(%) leaf 2.23 0.09 0.175 10.13 4.25 2.15 stem ---- 0.08 0.009 6.06 1.23 0.51 Si(mg/g) Zn(mg/g) Cu(mg/g) Fe(mg/g) leaf 0.07 37 5 150 stem 0.01 16 3 20
The degree to which spiny hopsage provides environmental protection for wildlife species in two western states is as follows :
Pronghorn Poor Fair
Bighorn ____ ____
Elk Poor Poor
Mountain goat ____ ____
Mule deer Poor Poor
White-tailed deer ____ Poor
Small mammals Fair ____
Small nongame birds Fair ____
Upland game birds Fair Fair
Waterfowl Poor ____
Spiny hopsage has moderate potential for erosion control and low to high potential for long-term revegetation projects . It can improve forage, control wind erosion, and increase soil stability on gentle to moderate slopes [27,54]. Spiny hopsage is suitable for highway plantings on dry sites in Nevada . Generalized characteristics for use in rehabilitation are as follows :
Adaptation attribute Rating establishment by seed medium establishment by transplant medium seed production & handling medium natural spread by seed medium growth rate good soil stability medium natural vegetative spread very poor adaptability to disturbance mediumIn Idaho, spiny hopsage seedlings produced from bareroot stock were of marginal quality . Larger stock (size class 2-0 or larger, that is grown 2 years indoors and 0 years outdoors) typically produces better results than 1-0 size stock (grown 1 year indoors, 0 years outdoors) . Spiny hopsage has been successfully transplanted onto mine spoils in Wyoming and Utah [17,35]. The following results were reported after spiny hopsage was transplanted onto replaced topsoil in southeastern Wyoming :
# of individuals # of individuals survival transplanted surviving (%) 25 10 40 First-year survival of front-end loader transplants (soil pH 7.0-8.0): # of individuals # of individuals survival transplanted surviving (%) 90 64 71Five years after establishment, spiny hopsage transplanted onto processed oil shale at a Uinta Basin, Utah, site had a 56% survival rate with an average height of 12 inches (30 cm) . Spiny hopsage seedlings have been successfully transplanted onto arid roadsides in the eastern Sierra Nevada of California . Container stock has been successfully used for reclamation of reconstructed soils after mining activities .
Spiny hopsage can be seeded directly onto disturbed sites in northern shrub steppe communities . Best results are generally obtained when seeds are planted in late fall or early winter which provides stratification [57,54]. Seed remains viable up to 2 years in storage. Plummer  recommends selecting seed by matching an ecotype that grows under conditions similar to those where it is to be planted. According to Plummer , "plant characteristics such as growth form, rooting depth, palatability, ease of establishment, and resistance to grazing should be used." Spiny hopsage seed is commonly cleaned by hammermilling to remove appendages from the utricles and then fanned to remove debris . Seedling establishment for broadcast and planted seeds was as follows :
Seedbed Seeds with Seeds with characteristics entire bracts bracts removed (%) (%) loose surface 18 2 smooth surface 7 0 packed surface 4 0 seeds planted 0.5 cm deep 51 48Variable results have been reported for spiny hopsage cuttings . Fair success is reported for rooting of stem cuttings treated with 0.3 percent to 0.8 percent IBA powder in late winter and early spring [27,48].
Some Native American peoples traditionally ground parched seeds of spiny hopsage to make pinole flour .
composition (%) cover (shrubs/m2) grazed 17 0.378 ungrazed 19* 0.533* _____________________________________________________ *significant difference between treatments (p<0.05)Spiny hopsage sprouts readily after roto-beating or light burning and is somewhat resistant to application of 2,4-D. It is easily killed by plowing with a heavy disk .
Spiny hopsage accumulates potassium in its leaves to such an extent that decay of the leaf litter may raise the surface soil pH beneath the canopy. These soil changes may affect future growth of spiny hopsage and other shrubs growing in association . However, according to Rickard and Keough , "whether these mineral concentrations will tend to make the soil more or less suitable for future generations of shrubs remains to be seen."
Spiny hopsage is a woody, erect, diffusely branched native shrub that reaches 1 to 5 feet (0.3-1.5 m) in height [7,23,27]. Branches are more or less spine-like at the tips . Spiny hopsage is evergreen in the southern deserts and deciduous in the summer in the northern deserts . Spiny hopsage is generally dioecious, although in some populations approximately 5% of the individuals are monoecious [7,8]. The fruit is a wing-margined utricle . The root system is shallow and spreading .
Spiny hopsage is relatively long-lived .
Spiny hopsage regenerates vegetatively by sprouting after top-killing disturbances such as fire . Spiny hopsage also regenerates from wind or gravity-dispersed winged seed, which is produced annually [37,46,66]. Seed production is variable. Plummer and others  describe seed production as "poor" in Utah whereas Daubenmire  reports that spiny hopsage produces an abundance of seed in Washington.
Persistent bracts apparently modify the microenvironment on the surface of the seedbed and aid in germination . Light has little effect on germination of spiny hopsage . However, habitat-correlated variation in germination patterns has been reported . Populations from the northern part of the species? range require cold temperatures to break dormancy . Seeds readily germinate without pretreatment . However, germination can be improved by cold stratification or dry storage [27,57]. Dormancy in spiny hopsage may represent an adaptation which delays germination until early spring when soil moisture conditions are most favorable . Detailed information on germination and seed characteristics is available [54,58]. Germination patterns reflect spiny hopsage's ability to germinate either late in the fall or early in the spring while moisture is available . Ecotypes apparently vary in germination response to temperature . Seed fill is variable, ranging from 18 to 95% . Spiny hopsage seed is reported to remain viable for 6 years in dry storage . However, Plummer  rates the seeds as having good viability for 2 years. Some limited 2nd and 3rd year germination has been reported .
Spiny hopsage accumulates seeds in states of primary or even secondary dormancy within the soil in the Mojave Desert. Secondary dormancy occurs when nongerminating seeds enter dormancy in response to environmental conditions. Shaw and others  report "determining whether spiny hopsage seeds are capable of entering secondary dormancy and affecting factors will require further investigation." Seedbanks can contribute to periodic episodes of good seedling establishment during moist years. Seedlings require chilling in order for the bud to break and growth to occur .
Spiny hopsage is fairly tolerant of alkaline and saline soils  and is typically found on highly calcareous alkaline soils. Its adaptation to alkalinity is low relative to other salt-desert chenopods such as shadscale and black greasewood . Some plants occur on neutral soils . Spiny hopsage occurs on a wide range of soil textures from gravel, sand, and sandy loams to heavy clay [10,27,66], but it prefers sandy soils that are free of salt and hardpans . Potassium is accumulated in spiny hopsage leaves and may comprise up to 63 to 73% of the total cations present. Spiny hopsage concentrates potassium in the surface soils beneath the canopy through decomposition of leaf litter .
Spiny hopsage grows from 524 feet to 9,514 feet (160-2900 m) in elevation . Elevational ranges are as follows [10,64]:
4,000 to 7,000 feet (1219-2134 m) in Colorado
2,500 to 7,500 feet (762-2286 m) in Nevada
2,000 to 5,500 feet (610-1676 m) in Utah
4,100 to 6,800 feet (1,250-2073 m) in Wyoming
Spiny hopsage grows in a number of undisturbed sagebrush and saltbush desert shrub communities. It grows on disturbed sites such as coppice dunes . According to Webb and others , it quickly reasserts dominance over colonizers on debris flows in the Panamint Mountains of California. The authors measured response rates of desert plants to disturbance in Death Valley National Monument. Plant assemblages were measured to quantify recovery rates and models developed to account for vegetative change based on principal component analysis following townsite abandonment, disturbances along a pipeline corridor, and on plant assemblages on new, several thousand-year old, and ancient (> 5,000-year-old) mud/debris flows. The following successional pathway has been proposed for mud/debris flows in Death Valley, California :
1) annuals - filaree (Erodium spp.) and brome (Bromus spp.) colonize
2) lupine (Lupinus spp.)/saltbush (Atriplex spp.)/penstemon (Penstemon spp.)/
buckwheat (Eriogonum spp.), and rabbitbrush (Chrysothamnus spp.) establish
3) wolfberry (Lycium spp.)/spiny hopsage/Nevada ephedra (Ephedra nevadensis) and blackbrush
4) spiny hopsage and Nevada ephedra dominate and initially colonizing species decline
5) blackbrush increases at the expense of Nevada ephedra, spiny hopsage, and wolfberry (may take more than 5,000 years)
6) blackbrush grows in nearly pure stands (may take 10,000 years to develop)
Leaves of spiny hopsage generally appear in late February and early March . In a Nevada study on the Great Basin-Mojave Desert interface, plants first leafed out from 2/2 to 3/20, with a mean date of 2/26 . At a second Nevada site within the Great Basin, average leaf bud break took place on March 19 .
Spiny hopsage sheds its leaves much earlier than are those of many other deciduous desert shrubs . In southern Nevada, leaves generally drop between mid-April and mid-May . Leaves are usually shed by mid-July in most locations , but there is an ecotype in northern Utah that retains a higher percentage of leaves after the growing season .
Flowering is hastened by rainfall . Most of the growth, including flowering and fruiting, is completed by midsummer . In southern Nevada, first dates of flowering ranged from 2/26 to 4/9, with a mean date of 3/17 . General flowering dates for four western states are as follows [1,10]:
State Beginning of Flowering Flowering End of Flowering CO May May July MT June June June NV February/March March April UT April May JuneFirst dates of fruiting ranged from 3/10 to 4/20, with a mean date of 4/2 . Fruit maturity is generally reached in mid-July, just before leaf fall, but this differs among ecotypes [6,37]. Bud formation, leaf fall, and the onset of summer dormancy usually occur after seed dispersal, but there is wide variation in this characteristic . In central Utah, seeds matured from June 15 to July 17 over the course of a 5-year study .
Dormancy in spiny hopsage is one of the longest of desert shrubs . Spiny hopsage remains dormant throughout the hot, dry summer months . In southern Nevada, Ackerman and others  found that spiny hopsage became dormant when daytime air temperatures exceeded 104 degrees Fahrenheit (40oC). Summer rains will not cause initiation of new leaf growth . Fall rains and/or periods of low temperatures ranging from 41 degrees Fahrenheit (5 oC) to below 32 degrees Fahrenheit (0 oC) usually break dormancy .
Spiny hopsage is considered to be somewhat fire tolerant and often survives fires that kill sagebrush [7,55]. Spiny hopsage often sprouts after fire [9,7]. However, in some instances sprouting does not occur [51,55]. Failure to sprout may be due to stressful conditions brought about by overgrazing and erosion .
The range of fire intervals reported for some species that dominate communities where spiny hopsage occurs are listed below. To learn more about the fire regimes in those communities refer to the FEIS summary for those species, under ?Fire Ecology or Adaptations.?
ponderosa pine (Pinus ponderosa) 2-42 years
basin big sagebrush (Artemisia tridentata ssp. tridentata)
mountain big sagebrush (A. tridentata ssp. vaseyana)
Wyoming big sagebrush (A. tridentata ssp. wyomingensis)
Small shrub, adventitious-bud root crown
Secondary colonizer - off-site seed
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".
Spiny hopsage is generally top-killed by fire . Plants often survive fires that kill adjacent sagebrush . Mature spiny hopsage generally sprout after being burned . Spiny hopsage is reported to be least susceptible to fire during summer dormancy .
Spiny hopsage often sprouts after plants are damaged by fire or mechanical injury . Sprouting may occur when mature plants are burned off at the soil surface. Fires in spiny hopsage sites generally occur in late summer when plants are dormant, and sprouting generally does not occur until the following spring . Holsinger  noted that apparently dead spiny hopsage plants resprouted several years after a wildfire in the Dautrich Memorial Desert Preserve near the Snake River in Canyon County, Idaho. These plants were located on the north-facing slopes of a basalt mesa .
Variation in sprouting among populations and possible relationships of sprouting to season and intensity of burn is possible, but has not yet been documented .
Fire may be most damaging to spiny hopsage when plants are actively growing . Mortality of spiny hopsage after a July wildfire in southeastern Washington was attributed to "stressed growing conditions imposed by an alkaline-sodic rooting substrate" . Several decimeters of soil had been lost due to earlier overgrazing and subsequent erosion and only a thin soil layer remained above a deep alkaline-sodic rooting substrate .
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