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Picrothamnus desertorum

• INTRODUCTORY
• DISTRIBUTION AND OCCURRENCE
• BOTANICAL AND ECOLOGICAL CHARACTERISTICS
• FIRE ECOLOGY
• FIRE EFFECTS
• MANAGEMENT CONSIDERATIONS
• REFERENCES

INTRODUCTORY

AUTHORSHIP AND CITATION FEIS ABBREVIATION SYNONYMS NRCS PLANT CODE COMMON NAMES TAXONOMY LIFE FORM FEDERAL LEGAL STATUS OTHER STATUS
	Photos © Larry Blakely

Bud sagebrush is not known to hybridize with other species [30,69].

DISTRIBUTION AND OCCURRENCE

• GENERAL DISTRIBUTION
• ECOSYSTEMS
• STATES
• BLM PHYSIOGRAPHIC REGIONS
• KUCHLER PLANT ASSOCIATIONS
• SAF COVER TYPES
• SRM (RANGELAND) COVER TYPES
• HABITAT TYPES AND PLANT COMMUNITIES

In the Surprise Valley of California, Young and others [40] list a community type of spiny hopsage (Grayia spinosa)/bud sagebrush/Indian ricegrass (Achnatherum hymenoides).

In the Churchill Canyon watershed of Nevada, Blackburn and others [7] describe a habitat type of black greasewood (S. vermiculatus)/bud sagebrush/desert needlegrass (A. speciosum) with a black greasewood/bud sagebrush community type as a component. They also delineate a shadscale (Atriplex confertifolia)/bud sagebrush community type in the same watershed. In Nevada's Cow Creek watershed there are several community types with bud sagebrush as a dominant. These are [6]:

shadscale/bud sagebrush/winterfat (Krascheninnikovia lanata)
shadscale/bud sagebrush/black greasewood
shadscale/bud sagebrush/bottlebrush squirreltail (Elymus elymoides)
black greasewood/shadscale/bud sagebrush

In the Great Salt Lake Desert of Utah, Vest [62] describes a shadscale/bud sagebrush community type, and bud sagebrush is a "subdominant" in saltbush, horsebrush (Tetradymia spp.), and winterfat communities in desert shrub of western Utah [20]. Wyoming's Red Desert has a cover type of bud sagebrush on alluvial flats [10].

Associates: Bud sagebrush occurs in several ecosystems. Its more common associates in some of these ecosystems include:

Desert shrub: shadscale, fourwing saltbush (A. canescens), valley saltbush (A. cuneata), Gardner's saltbush (A. gardneri), low rabbitbrush (Chrysothamnus viscidiflorus var. stenophyllus), green molly (Kochia americana), winterfat, spiny hopsage, and horsebrushes [3].

Sagebrush (Artemisia spp.): big sagebrush (Artemisia tridentata), birdfoot sagebrush (A. pedatifida), green rabbitbrush (C. viscidiflorus ), rubber rabbitbrush (C. nauseosus), granite prickly phlox (Leptodactylon pungens), western wheatgrass (Pascopyrum smithii), Indian ricegrass, and bluegrasses (Poa spp.) [13].

Sagebrush/grassland: big sagebrush, rubber rabbitbrush, western wheatgrass, and Indian ricegrass [14].

Salt-desert scrub: black greasewood, shadscale, Gardner's saltbush, fourwing saltbush, spiny hopsage, and winterfat [43].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

• GENERAL BOTANICAL CHARACTERISTICS
• RAUNKIAER LIFE FORM
• REGENERATION PROCESSES
• SITE CHARACTERISTICS
• SUCCESSIONAL STATUS
• SEASONAL DEVELOPMENT

Bud sagebrush is a native, summer-deciduous shrub [9]. It is small, round, and prickly with a height of 4 to 10 inches (10-25 cm) and a spread of 8 to 12 inches (20-30 cm) [30]. This low, spinescent, pungently aromatic shrub is profusely branched from the base [36,68]. After leaves and flowers fall from the plant, the flower stalks become woody, dry spines that may persist for several seasons [68]. Bud sagebrush's fruits are an oblong or ellipsoid hairy achene [56]. Dittberner and Olson [15] report bud sagebrush is endomycorrhizal.

Bud sagebrush is well adapted to xeric conditions. A layer of interxylary cork is formed annually over the last year's wood in both roots and stem. This layer of cork restricts upward movement of water to the very narrow zone of wood formed by the current year's growth and helps prevent water loss during the dormant season [36,68].

Roots: Bud sagebrush's root system is more branched and penetrates the soil more deeply than its associated shrub species. This allows bud sagebrush more efficient utilization of limited spring moisture [9,69]. However, the Institute for Land Rehabilitation [30] describes bud sagebrush's root system as shallow and fibrous. Bud sagebrush's extensive root system has a short, thick, vertical taproot up to 6 inches (15 cm) with many small horizontal side branches [68,69]. Bud sagebrush's root system grows primarily in the top 6 to 21.7 inches (15-55 cm) of soil [36]; but in gravel-free sandy soils, roots may extend up to 6 feet (1.8 m) [68].

Occasionally bud sagebrush produces adventitious roots. This occurs when the lowest branches are completely covered by soil. Bud sagebrush growing in bottomlands produce adventitious roots more often than those growing on benches [69].

RAUNKIAER [44] LIFE FORM:
Chamaephyte

REGENERATION PROCESSES:
Breeding system: Bud sagebrush is monoecious [42].

Pollination: Bud sagebrush is wind pollinated [42].

Seed production: Good seed production occurs infrequently because bud sagebrush blooms so early in the spring developing embryos are frequently frozen [36].

Seed dispersal: Sagebrush seed in general has very poor dispersal. It lacks appendages for airborne transport by the wind or for attachment to animals. Most sagebrush seed falls beneath the parent plant and moves 3 feet (0.9 m) or less per generation [50]. There is no specific information about seed dispersal for bud sagebrush.

Seed banking: No information

Germination: Bud sagebrush has small seeds, 641,250/per ounce (2,250/gm) [4], and germination is low [30]. Flowerheads fall from the plant intact without breaking apart to release the seeds. Sometimes seed germinates while still in the head [36,68].

Seedling establishment/growth: Bud sagebrush was planted at the Black Butte mine in Wyoming as part of a wildlife improvement project and had 64% plant establishment the 1st year [51]. In an experiment at the Desert Experimental Range in southwestern Utah, West [66] compared survival of bud sagebrush plants in grazed and ungrazed plots. In 4 ungrazed plots, seedlings of bud sagebrush established in 1935 and 1936 were counted until 1968. The spring of 1936 was drier than average and had poor seed production; shrub seedlings were rare. West [66] speculates that difference in survival for the 2 cohorts may be a function of initial plant size, especially root structure, with the 1936 cohort being influenced by the dry spring. Percent survivorship was:

Wood [68] states soil must be wet for 30 days or bud sagebrush seedlings will not survive.

Asexual regeneration: Everett and others [17] tested propagation of Nevada shrubs by stem cuttings and found bud sagebrush to be one of the "...most easily propagated." Bud sagebrush also can regenerate by layering [69].

Elevation: Within the Great Basin bud sagebrush has an elevational range of 4,000 to 5,400 feet (1,219-1,646 m) [30]. Altitudinal ranges for individual states are:

Arizona: 5,500 to 6,000 feet (1,676-1,829 m) [33]
California: 2,953 to 5,249 feet (900-1,600 m) [28]
Colorado: 4,500 to 8,000 feet (1,372-2,438 m) [27]
Nevada: 2,300 to 6,800 feet (701-2,073 m)  [50]
Utah: 3,937 to 6,316 feet (1,200-1,925 m) [65]

Soils: Hutchings [29] states bud sagebrush ordinarily grows on slightly alkaline soil. The Institute for Land Rehabilitation [30] describes soils that bud sagebrush grows on as shallow, loamy, well-drained, and slightly alkaline. In a study of community types in the Great Salt Lake Desert of Utah, Vest [62] analyzed the soil in a shadscale/bud sagebrush community. His specific findings support the general statements of Hutchings [29] and The Institute for Land Rehabilitation [30]. The pH of the soil in a shadscale/bud sagebrush community in Utah was [62]:

Vest reported salt content, expressed as percent of the oven-dry weight of the samples as:

Soil texture in the same community was expressed as percent of oven-dry weight:

Early: Webb and others [64] characterize bud sagebrush as a pioneer species on disturbed sites in California's Death Valley National Monument.

Mid-successional: In the Great Salt Lake Desert of Utah, bud sagebrush is a mid-seral species on vegetated-dune communities [62].

Climax: Bud sagebrush is a component of climax vegetation on dense clay and clayey soil types in Montana [46].

SEASONAL DEVELOPMENT:
Bud sagebrush is a summer-deciduous shrub. Depending on growing season conditions bud sagebrush may initiate growth in early March and be dormant by late June [9]. In a study observing phenology of desert shrubs in southern Nye County, Nevada, bud sagebrush always became dormant when daytime air temperatures were over 104 degrees Fahrenheit (40 ^oC) and did not break dormancy even after summer rains but always broke dormancy after fall rains [1]. Chambers and Norton [9] discuss summer dormancy of bud sagebrush in Utah and state that when fall precipitation is sufficient to penetrate the soil from 9.8 to 11.8 inches (25-30 cm), bud sagebrush will break dormancy and produce new leaves but the stems will not elongate. This enables bud sagebrush to evade summer drought yet still take advantage of late-summer rain. Plants then remain green all winter providing succulent forage throughout winter and spring [30].

In southwestern Utah, Wood and Brotherson [69] gave supplemental water to a group of natural bud sagebrush seedlings and gave no supplemental water to another group. The group with supplemental water broke summer dormancy on August 28 and the group of seedlings without supplemental water broke summer dormancy 2 weeks later.

In 2 shadscale/galleta (Pleuraphis jamesii) sites in Nevada separated by 34.2 miles (55 km), bud sagebrush broke winter dormancy on March 22nd (southern-most site) and March 24th [18]. Hutchings [29] states growth begins early in March or April as soon as the weather becomes warm, and flowers are produced in May. Seed is shed at the end of June [30].

FIRE ECOLOGY

• FIRE ECOLOGY OR ADAPTATIONS
• POSTFIRE REGENERATION STRATEGY

Fire regimes: Fires in deserts are historically more rare than in most western ecosystems. The more arid the desert, the less fuel produced and the less frequent and severe are any fires that may occur. However, even though fire frequency and severity may be relatively low, fire's effect on the ecosystem may be severe. The Great Basin Desert is a cold-desert area characterized by a variety of shrubs with a generally sparse understory. Plant communities are usually dominated by big sagebrush or shadscale. Bud sagebrush is similar to shadscale in general growth form, and like shadscale communities, bud sagebrush communities rarely burn [47].

The following table provides fire return intervals where bud sagebrush may be an important component of the vegetation. 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".

FIRE EFFECTS

• IMMEDIATE FIRE EFFECT ON PLANT
• DISCUSSION AND QUALIFICATION OF FIRE EFFECT
• PLANT RESPONSE TO FIRE
• DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
• FIRE MANAGEMENT CONSIDERATIONS

MANAGEMENT CONSIDERATIONS

• IMPORTANCE TO LIVESTOCK AND WILDLIFE
• VALUE FOR REHABILITATION OF DISTURBED SITES
• OTHER USES
• OTHER MANAGEMENT CONSIDERATIONS

When bud sagebrush 1st shows signs of breaking winter dormancy, but before buds elongate, the bark can be easily removed from the previous season's growth by pulling. This condition is referred to as "slipping." At this time, bud sagebrush becomes palatable to domestic sheep. After the new twigs have elongated somewhat, bud sagebrush's palatability drops because the volatile oils increase. Cattle and horses seldom utilize bud sagebrush, possibly because of its aromatic oil content [68,69].

Smith and Beale [53] observed pronghorns in Utah from 1961 through 1970. They found during spring (16 March-15 June) bud sagebrush made up 18 to 35% of pronghorn diet. Bud sagebrush received highest utilization of any plant on western Utah deserts by pronghorns in the spring. The same study determined pronghorns ate no bud sagebrush during winter, bud sagebrush was <1% of the winter diet of cattle and 4% of the winter diet of domestic sheep. Gullion [26] lists bud sagebrush as "excellent" forage for Nevada pronghorn in spring.

Bud sagebrush is rated as "regularly, frequently, or moderately taken" by mule deer in Nevada in winter and is utilized by bighorn sheep in summer, but the importance of bud sagebrush in the diet of bighorns is not known [26].

Black-tailed jackrabbits and small rodents generally eat only leaves, small branches, and twigs of bud sagebrush. However, black-tailed jackrabbits may occasionally prune back an entire plant [68,69].

Chukars eat leaves and seeds of bud sagebrush in Nevada [26]. Sage thrashers appear to prefer territories with great amounts of black sagebrush (Artemisia nova), shadscale, and bud sagebrush in the Great Basin [37]. However, Wiens and others [67] did a statistical analysis of birds and shrubs in the Great Basin and found a significant (P<0.05) negative correlation between presence of bud sagebrush and sage thrashers and Brewer's sparrows. They found a significant (P<0.05) positive correlation between bud sagebrush and presence of mourning doves and loggerhead shrikes.

Palatability/nutritional value: Palatability of bud sagebrush is reported differently by different investigators. Chambers and Norton [9] report bud sagebrush is palatable to livestock the whole year. Cook and Harris [11] state bud sagebrush is "highly relished" by livestock in early spring, but later in spring, volatile oils increase and livestock avoid bud sagebrush. They also report bud sagebrush is not readily eaten during fall and winter because only a few dry leaves remain and only the spiny twigs and woody base are available to livestock.

In Utah Green and others [25] studied winter range of domestic sheep. They found domestic sheep frequently browsed 70% of bud sagebrush during the 1st contact. This represented all the domestic sheep could readily take, and only stumps of shoots and a limited amount of leafy material protected by coarse wood remained. Hutchings [29] describes bud sagebrush as a "good" forage species for domestic sheep that is browsed all winter long but is eaten most readily in late winter when growth begins. During this time bud sagebrush is of value to the welfare of browsing animals, especially where there is abundant dry grass to supplement their diet [30].

In a study of "major desert plants" during winter grazing season in Utah, Cook and Harris [11] determined average chemical constituents and average digestibility of bud sagebrush:

Cover value: Bud sagebrush is rated as poor cover for big game, upland game birds, and waterfowl. In Utah it is described as "fair" cover for nongame birds and small mammals [15].

Bud sagebrush is difficult to seed [45] but because of its shallow, fibrous root system, bud sagebrush can be used for soil stabilization and erosion control [30].

Two states list bud sagebrush as a plant suitable for reclamation or landscaping. Utah describes bud sagebrush as suitable for transplanting in mountain chaparral, pinyon/juniper (Pinus spp/Juniperus spp), Douglas-fir/white fir (Pseudotsuga menziesii/Abies concolor), quaking aspen/lodgepole pine (Populus tremuloides/Pinus contorta), ponderosa pine (P. ponderosa), and sagebrush [57]. The state of Nevada lists bud sagebrush as a "preferred" plant for highway plantings in salt-desert shrub communities [54].

OTHER USES:
Bud sagebrush is an indicator of alkaline soils [56].

OTHER MANAGEMENT CONSIDERATIONS:
Bud sagebrush is highly susceptible to effects of browsing. It decreases under browsing due to year-long palatability of its buds and is particularly susceptible to browsing in the spring when it is physiologically most active [9]. Hutchings [29] recommends 50% of annual growth be the maximum browsed. Heavy browsing may kill bud sagebrush rapidly [69].

Picrothamnus desertorum: REFERENCES

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