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SPECIES:  Encelia farinosa
Brittlebush flowering in Palm Canyon, CA. Wikimedia Commons image by Stan Shebs, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=200733.

 


Introductory

SPECIES: Encelia farinosa
AUTHORSHIP AND CITATION : Tesky, Julie L. 1993. Encelia farinosa. 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/shrub/encfar/all.html [].
ABBREVIATION : ENCFAR SYNONYMS : Encelia farinosa var. farinosa Encelia farinosa var. phenicodonta (Blake) I. M. Johnston Encelia farinosa var. radians Brandegee ex. Blake [35] NRCS PLANT CODE : ENFA COMMON NAMES : brittlebush inceinso white brittlebush TAXONOMY : The currently accepted scientific name for brittlebush is Encelia farinosa Gray ex. Torr. [1,35,46]. LIFE FORM : Shrub FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


DISTRIBUTION AND OCCURRENCE

SPECIES: Encelia farinosa
GENERAL DISTRIBUTION : Brittlebush grows in the interior valleys of coastal southern California (San Bernardino Valley, Lake Elsinore, western San Diego County, and west Riverside County), Baja California, southern Nevada in Clark County, southwestern Utah, southern and western Arizona, and northwestern Mexico [1,35,46,52].  It is adventitious in Hawaii [55].
Distribution of brittlebush in the United States. Map courtesy of USDA, NRCS. 2018. The PLANTS Database. National Plant Data Team, Greensboro, NC [2018, July 6] [41].
ECOSYSTEMS : 
   FRES28  Western hardwoods
   FRES29  Sagebrush
   FRES30  Desert shrub
   FRES33  Southwestern shrubsteppe
   FRES34  Chaparral - mountain shrub
   FRES35  Pinyon - juniper
   FRES40  Desert grasslands


STATES : 
     AZ  CA  HI  NV  UT  MEXICO



BLM PHYSIOGRAPHIC REGIONS : 
    3  Southern Pacific Border
    7  Lower Basin and Range
   12  Colorado Plateau


KUCHLER PLANT ASSOCIATIONS : 
   K023  Juniper - pinyon woodland
   K024  Juniper steppe woodland
   K030  California oakwoods
   K033  Chaparral
   K034  Montane chaparral
   K035  Coastal sagebrush
   K040  Saltbush - greasewood
   K041  Creosotebush
   K042  Creosotebush - bursage
   K043  Paloverde - cactus shrub
   K044  Creosotebush - tarbush
   K053  Grama - galleta steppe
   K054  Grama - tobosa prairie
   K055  Sagebrush steppe
   K056  Wheatgrass - needlegrass shrubsteppe
   K057  Galleta - three-awn shrubsteppe
   K058  Grama - tobosa shrubsteppe
   K061  Mesquite - acacia savanna
   K064  Grama - needlegrass - wheatgrass
   K065  Grama - buffalograss
   K087  Mesquite - oak savanna


SAF COVER TYPES : 
    68  Mesquite
    72  Southern scrub oak
   239  Pinyon - juniper
   241  Western live oak
   242  Mesquite
   255  California coast live oak


SRM (RANGELAND) COVER TYPES : 
NO-ENTRY


HABITAT TYPES AND PLANT COMMUNITIES : 
Brittlebush occurs in pine-oak (Pinus-Quercus) and open oak woodlands,
semidesert and desert grasslands, desert scrub, and coastal sage scrub.
Throughout most of its range, brittlebush is the dominant shrub.  It
forms extensive monospecific stands in many areas.  On south-facing
slopes and bajadas of the lower Colorado Valley in the Sonoran Desert,
vegetation is dominated by brittlebush.  On other sites in this area,
brittlebush often codominants with creosotebush (Larrea tridentata) and
teddy-bear cholla (Opuntia bigelovii) [51].  Brittlebush is also
codominant in the brittlebush-wishbonebush (Mirabilis laevis)
association, which usually occurs in coastal sage scrub on south-facing
moderately, steep slopes.  The publication describing this association is
"The community composition of California coastal sage scrub" [18].

Brittlebush is often associated with palo verde (Cercidium spp.),
saguaro (Carnegiea gigantea), fairy duster (Calliandra eriophylla),
Janusia graciles, agave (Agave spp.), creosotebush, Anderson wolfberry
(Lycium andersonii), white bursage (Ambrosia dumosa), canyon ragweed
(Ambrosia ambrosioides), Opuntia spp., whitethorn acacia (Acacia
constricta), catclaw acacia (A. greggii), fourwing saltbush (Atriplex
canescens), desert hackberry (Celtis pallida), honey mesquite (Prosopis
glandulosa var. glandulosa), and several species of perennial bunchgrass
[4,14,15,28,29].

MANAGEMENT CONSIDERATIONS

SPECIES: Encelia farinosa
IMPORTANCE TO LIVESTOCK AND WILDLIFE : Brittlebush is a browse species of desert mule deer and desert bighorn sheep [19,48].  Brittlebush has no forage value for domestic livestock [15].  In a laboratory study, kangaroo rats ate brittlebush seeds, but they were not preferred [23].  Several species of breeding birds inhabit the brittlebush-ironwood (Olneya tesota) community of foothills and bajadas [17]. PALATABILITY : NO-ENTRY NUTRITIONAL VALUE : Nutritional values of brittlebush collected bimonthly in the Picacho Mountains of Arizona in 1983 are as follows [19]:                                       Fiber %         Dry Matter %   Protein %     ADF    NDF      Lignin %    Jan-Feb   36.86         11.04       22.31  30.36     5.48 Mar-Apr   38.23         9.28        20.67  28.86     5.87 May-June  49.56         8.49        28.74  38.98     8.08 July-Aug  72.02         3.28        48.72  63.88     13.64 Sept-Oct  38.28         8.60        28.28  34.84     7.60 Nov-Dec   31.84         12.70       26.11  31.27     8.74 ADF-acid detergent fiber NDF-nonacid detergent fiber Nutritional value of brittlebush has also been analyzed by Seegmiller and others [48] and Rautenstrauch and others [33]. COVER VALUE : VALUE FOR REHABILITATION OF DISTURBED SITES : Brittlebush is most valuable for rehabilitating low maintenance landscapes, critical stabilization areas, and disturbed areas.  It is easily transplanted or can be established by direct seeding.  Seeds and plants are available in limited quantities [38].  Brittlebush is used to minimize erosion and sediment damage near highways in Arizona [6]. OTHER USES AND VALUES : The stems of brittlebush exude a clear resin used by the Indians as glue and chewing gum.  In the churches of some parts of Mexico the resin is burned as incense [1,46].  The Seri Indians of Sonora, Mexico, use the brittlebush twigs as a remedy for toothaches.  They also grind the resin and sprinkle it on sores [12]. OTHER MANAGEMENT CONSIDERATIONS : Brittlebush infestation reduces forage production because brittlebush competes strongly with buffelgrass (Cenchrus ciliarus).  Several studies were conducted to determine the effectiveness of mechanical and chemical brittlebush control.  Mowing killed few plants but temporarily reduced growth.  Hand removal resulted in 100 percent mortality, but brittlebush seedlings rapidly reinvaded and densities were equal to pretreatment levels after 3 months.  Soil-applied pelleted tebuthiuron and picloram control brittlebush.  High intensity livestock grazing reduced brittlebush growth, but caused no significant change in brittlebush density after 3 years [53].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Encelia farinosa
GENERAL BOTANICAL CHARACTERISTICS : Brittlebush is a native, drought-deciduous, perennial shrub [7,8,21,28].  It grows to about 5 feet (1.5 m).  It has a woody base and is rounded and much-branched in form.  Thick branches support an umbrella of leaves with few stems beneath [7].  The leaves are 0.7 to 2 inches (2-5 cm) long and 0.6 to 1 inch (1.5-2.5 cm) broad.  They are mostly located toward the end of branches [35].  The flowering heads are loosely clustered on long naked branchlets [1,35].  Brittlebush is short lived.  On permanent plots in the Sonoran Desert, the maximum observed longevity was 32 years [54].
Brittlebush flowers. Wikimedia Commons image by Stan Shebs.
Brittlebush generally has shallow roots [27].  One study found that the
root system of brittlebush on a north-facing slope was composed of a
stout taproot and numerous laterals.  All laterals bore groups of
filamentous roots [8].


RAUNKIAER LIFE FORM : 
  
   Phanerophyte


REGENERATION PROCESSES : 
Sexual reproduction - Brittlebush reproduces almost exclusively by seed
[7,45].  Seeds are dispersed long distances by wind.  Brittlebush often
germinates prolifically after heavy winter rains [7].  Plants are not
frost tolerant, and frost may damage leaves and stems [39].

Reproduction may be reduced by interspecific competition.  Growth and
productivity of brittlebush is limited by the low precipitation in its
native habitat.  Neighboring brittlebush further decrease water availability,
reducing brittlebush productivity [51].

Vegetative reproduction - Brittlebush can sprout from the root crown
[7,26].

Brittlebush is allelopathic.  The leaves produce a toxic, water-soluble
substance that inhibits the growth of several winter annuals [24].


SITE CHARACTERISTICS : 
Brittlebush is commonly found on dry, rocky or gravelly slopes and
mesas [1].  In the Sonoran Desert brittlebush is common on
south-facing, granitic slopes, volcanic slopes, upland flats, and
alluvial flats [44].  In coastal sage scrub brittlebush grows on soils
derived from alluvial deposits, sandstone, granite and diorite [44].  It
also grows on desert pavement [33].  Brittlebush grows poorly on clay
soils [16].  It occurs at elevations up to 3,000 feet (915 m)
[38,46,47].

Brittlebush is restricted to climates with long periods of limited
moisture.  The total amount of precipitation in these areas is quite
variable.  The seasonal pattern of rainfall is also variable, with some
brittlebush areas receiving most of the rain in winter, and other areas
receiving mostly summer rain [50].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Brittlebush usually occurs in initial and early seres [7,31,34,42]. It
is an early colonizer of disturbed sites, often replacing long-lived
perennials in postfire communities [7,31,34,40].  An open brittlebush
community may persist for decades [7].  In permanent plots in the
Sonoran Desert, brittlebush density and cover was more or less stable
over 72 years.  However, only 17 percent of seedlings survived to the
seventh year [54].


SEASONAL DEVELOPMENT : 
Brittlebush leaves and flowers are formed whenever the water relations
are favorable [8].  This can occur any time from November through May
[35].  Under extreme drought conditions brittlebush becomes dormant and
the leaves are shed [21,50].  Brittlebush also shows seasonal variation
in leaf density and thickness.  During times of available water, leaves
expand more, are less pubescent, are less capable of reducing water
loss, and have lower resistance to carbon dioxide flux.  These
characteristics are reversed as soil water decreases and the more
mesophytic leaves abscise [50].

FIRE ECOLOGY

SPECIES: Encelia farinosa
FIRE ECOLOGY OR ADAPTATIONS : Brittlebush is a good initial offsite colonizer of postfire communities via wind dispersed seeds [7,22,26].  It also has some ability to sprout from the root crown, which may be limited by intolerance of heat [45]. Brittlebush does not accumulate organic material and windblown soil beneath its crown, as do multiple-stemmed shrubs [49].  Recurrent fires select for short-lived desert shrubs such as brittlebush at the expense of long-lived species [7]. POSTFIRE REGENERATION STRATEGY :    Initial-offsite colonizer (off-site, initial community)    Small shrub, adventitious-bud root crown

FIRE EFFECTS

SPECIES: Encelia farinosa
IMMEDIATE FIRE EFFECT ON PLANT : Brittlebush is often top-killed or completely killed by fire.  Nearly all brittlebush plants in a coastal sage scrub community were top-killed or killed by a June 1981 fire [26].  Following a fast-moving, low-severity fire in creosotebush scrub, brittlebush plants were mostly scorched.  Only leaves and branches near the ground burned, leaving foliage on ultimate stems.  However, brittlebush suffered 93 percent mortality [7].  A hot summer fire in Sonora, Mexico, killed 32 percent of mature brittlebush plants and 60 percent of seedlings.  Burning in 2 consecutive years killed 70 percent of mature plants and 90 percent of seedlings.  The remaining plants were injured and had not recovered after 3 years [53]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Brittlebush wind-dispersed seeds readily invade postfire environments and often become well established [7,22].  Following prescribed fires in the upper Sonoran Desert, brittlebush underwent an initial 83 percent reduction in density, but within 9 months it increased to 762 percent of preburn density.  This was a result of very successful seed germination and subsequent seedling establishment [9].  In southern California coastal sage scrub, fires were followed by rapid brittlebush seedling establishment.  Brittlebush accounted for most of the seedlings observed during the first growing season.  Recent fires have converted cresotebush scrub at Palm Springs, California, to brittlebush coastal sage scrub [7]. Brittlebush is categorized as a weakly-sprouting species [7,26].  Three to five growing seasons after fire in creosotebush scrub, brittlebush sprouting was rare [7].  Following a June 15, 1981 wildfire in coastal sage scrub, only 4 to 30 percent of the top-killed brittlebush shrubs regenerated by crown sprouting.  Maximum sprouting occurred on north-facing slopes.  The likelihood of brittlebush recovery from fire by sprouting is greater on cool, less xeric sites where fires are often less severe, and less on the hot, xeric sites [26].  However, 1 year after a hot, summer fire in Sonora, Mexico, surviving brittlebush plants sprouted vigorously [53]. Postfire brittlebush densities for east and west exposures 1.5 years after a June coastal sage scrub fire were 79 to 205 percent of prefire densities on east, south, and west exposures.  On north-facing slopes, postfire brittlebush density was less than 4 percent of prefire density.  More than 90 percent of the regeneration consisted of seedlings [26]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : This fire study provides information on postfire responses of plant species in communities that include brittlebush: FIRE MANAGEMENT CONSIDERATIONS : NO-ENTRY

FIRE CASE STUDY

SPECIES: Encelia farinosa
FIRE CASE STUDY CITATION : Tesky, Julie L., compiler. 1993. Brittlebush response to fire in creosotebush scrub of the Sonora Desert, California. In: Encelia farinosa. 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/ []. REFERENCE : Brown, David E.; Minnich, Richard A. 1986. Fire and changes in creosote bush scrub of the western Sonoran Desert, California. American Midland Naturalist. 116(2): 411-422. [7]. SEASON/SEVERITY CLASSIFICATION : Beginning in 1978, a series of fires spread through dried herbaceous fuels into extensive areas of creosotebush (Larrea tridentata) scrub.  The flames reduced the herb layer to a low stubble, indicative of fast-moving, low-intensity fires.  Fires occurred in June, July, August, or September. STUDY LOCATION : Four sites, on Quaternary alluvial fans descending from the east scarp of the San Jacinto Mountains at the end of the Coachella Valley near Palm Springs, California, were chosen for study.  The four sites were located at the fire boundaries on the Chino, Blaisdell, and Palm canyon alluvial fans in order to compare burned vegetation with adjacent unburned stands. Fires occurred in the Chino Canyon fan (1,250 acres [500 ha], 1978), Blaisdell and Chino canyons (6,900 acres [2800 ha], 1980), and the east scarp and alluvial fans below 3,200 acres (1,300 m) from Chino Canyon to Palm Canyon (15,000 acres [6,000 ha], 1980).  A 3,000 acre (1,200 ha) fire in 1982 overlapped large areas burned in 1973 near Snow Creek.  In 1983, the first of three fires reburned portions of the Snow Creek area and Blaisdell Canyon.  Two smaller fires also occurred along Snow Creek road and Interstate 10. PREFIRE VEGETATIVE COMMUNITY : Most of the Sonoran Desert is covered with creosotebush scrub consisting of scattered low shrubs less than 6.6 feet (2 m).  Representative growth forms include evergreen sclerophyllous and deciduous shrubs, subligneous subshrubs, leaf and stem succulents, and annual herbs.  Bajadas and adjacent mountainsides in the Coachella Valley are covered by creosotebush, brittlebush (Encelia farinosa), big galleta (Hilaria rigida), hedgehog cactus (Echinocereus engelmannii), and Grays ratany (Krameria grayi). Vegetation on the plains and lower bajadas, including the study sites, is dominated by creosotebush, white bursage (Ambrosia dumosa), and brittlebush, which may form 60 to 100 percent of total vegetation cover.  Blue paloverde (Cercidium floridum), ironwood (Olynea tesota), smoketree (Dalea spinosa), beloperone (Beloperone californica), and desert lavender (Hyptis emoryi) are common along washes.  Succulents such as Ferocactus acanthodes, hedgehog cactus, beavertail cactus (Opuntia basilaris), teddy-bear cholla (O. bigelovii), and golden cholla (O. echinocarpa) reach maximum densities on sandy hillsides and bajadas with rocky, gravelly, or sandy substrates. TARGET SPECIES PHENOLOGICAL STATE : The phenological state of brittlebush at the time of the fires is unknown.  The areas were surveyed between April 25 and May 27 1983, when brittlebush was in full growth or flower. SITE DESCRIPTION : The climate of the Coachella Valley is extremely arid.  Average annual rainfall at Palm Springs is 5.4 inches (138 mm).  Summers are hot and dry, although there are occasional thunderstorms, mostly over the nearby mountains.  Coarse-textured soils are well-drained and moderately alkaline, with a minimum of organic matter.  No information was given as to the specific topography, slope, and elevation of each site. FIRE DESCRIPTION : The fires in creosotebush scrub characteristically spread during periods when ambient temperatures averaged 95 to 104 degrees Fahrenheit (35-40 deg C) and relative humidity ranged from 10 to 25 percent.  High winds were caused by the typical spring and early summer gravity acceleration of descending coastal marine air spilling through San Gorgonio Pass. Upcanyon winds and nocturnal air drainage promoted fire spread on the eastern face of Mt. San Jacinto.  The flames reduced the herb layer to a low stubble, indicative of fast-moving, low-intensity fires. FIRE EFFECTS ON TARGET SPECIES : The vegetation was sampled three growing seasons after fires at Blaisdell, Palm Canyon and Palm Indian sites and five growing seasons after fire at the Chino site.  Brittlebush plants were mostly scorched. Only leaves and branches near the ground burned, leaving foliage on higher stems.  However, brittlebush suffered 93 percent mortality. None of the severely burned brittlebush plants resprouted after fire; 16 percent of the scorched plants resprouted.  Brittlebush accounted for most of the seedlings observed during the first growing season.  The wet 1982-1983 season was followed by abundant reproduction of brittlebush in both burned and unburned sites.  After 3 to 5 growing seasons, the total cover in burned sites was about half that of unburned sites and was composed mostly of brittlebush. Density (D) and cover (C) of established (unburned) and resprouting (burned) brittlebush at two sites in the Sonoran Desert, California, are shown below.  Density is expressed in number of plants per 100 meters square.  Cover is expressed as percent ground covered.                  unburned      burned                   D     C      D    C    Chino           11.5   9.2    1.5  2.0  Palm Canyon     13.0  10.6    2.0  2.6 Palm Indian      3.0   1.4    2.5  3.5 Blaisdell        1.0   0.9    0.0  0.0 Brittlebush seedling density (number/ha) in initial and subsequent growing seasons was:                 1980-1981    1981-1983 Burned   1,460         7,010  Unburned    90         5,650 FIRE MANAGEMENT IMPLICATIONS : Fires are infrequent in the Sonoran Desert owing to limited biomass, wide spacing between shrubs and sparse ground cover.  Successional studies in creosotebush scrub reveal postdisturbance recolonization by long-lived species is very slow and may require hundreds of years. Fires may have long-term impacts on the structure and composition of this community.  Brittlebush is a good colonizer after fire.  Fires in creosotebush scrub have resulted in an increase in brittlebush frequency and density.  Recent fires have converted creosotebush scrub at Palm Springs to brittlebush coastal sage scrub similar in composition to the stands covering semiarid interior valleys around Riverside, California.

REFERENCES

SPECIES: Encelia farinosa
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