BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Encelia frutescens | Bush Encelia 



GENERAL BOTANICAL CHARACTERISTICS : 
Bush encelia is a short-lived, drought-deciduous, perennial, native
shrub.  It is rounded and many branched, growing from 1.5 to 5 feet
(0.5-1.5 m) tall [16,26].  Stems are ascending to erect.  Leaves are 0.4
to 0.8 inch (1-2 cm) long [16,17].  The seeds of bush encelia have flat
surfaces and low mass, accounting for their excellent lofting ability
[14].  The lifespan of bush encelia is unknown but is judged to be a few
decades [24].


RAUNKIAER LIFE FORM : 
   Hemicryptophyte


REGENERATION PROCESSES : 
Bush encelia reproduces sexually.  The seeds are dispersed by wind and
have excellent lofting ability, but will not disperse well from the
surface of the ground [14].  The fruit of bush encelia contains two
hairy awns on the tip that catch wind currents [14].  


SITE CHARACTERISTICS : 
Bush encelia is found in upland areas of low hills and alluvial valleys
in desert environments [25].  It is common on rocky slopes and on
impoverished, residual sands and gravels [21].  Bush encelia occurs in
areas with slow internal drainage where the water table is near the
surface of the soil.  In the Nevada Test Site area, the soils are highly
alkaline and may be salt encrusted at the surface [27].  Bush encelia is
a rare shrub in the Kelso Dunes area of the Mojave Desert [21].  It
occurs in spring and seepage areas of the Mojave Desert where the soils
are moist year-round or are seasonally saturated [27].  Bush encelia
inhabits naturally disturbed areas such as drainage channels and areas
with substrate alterations [18].

Elevation:  In the Mojave and Colorado deserts of southern California,
bush encelia occurs at elevations from 1,700 to 6,000 feet (525-1,830 m)
[18,25].  On rocky slopes and mesas of Arizona, bush encelia grows at
elevations up to 4,000 feet (1,200 m) [11].  In southwestern Utah, it is
found at elevations of 4,000 feet (1,220 m) [15].  In southern Nevada,
bush encelia can be found at elevations of 5,000 feet (1,500 m) [27].

Climate:  In the deserts of California, the seasonal and diurnal
temperatures are highly variable.  Mean summer maximum temperatures are
from 100 to 110 degrees Fahrenheit (37-42 deg C), and mean winter
minimum temperatures are from 30 to 42 degrees Fahrenheit (1.1-5.5 deg
C) [17].  The average annual precipitation in these desert environments
is from 2 to 8 inches (5.1-20.3 cm) [17].

Plant associates:  Common associates of bush encelia not mentioned in
Distribution and Occurrence include:  wirelettuce (Stephanomeria
pauciflora), shadscale (Atriplex confertifolia), teddybear cholla
(Opuntia bigelovii), rayless goldenhead (Acamptopappus sphaerocephalus),
desertholly (Atriplex hymenelytra), desertsenna (Cassia armata),
narrowleaf goldenbush (Happlopappus linearifolius), alkali goldenbush
(Haplopappus acradenius), iva (Iva acerosa), desert polygala (Polygala
acanthoclada), Cooper wolfberry (Lycium cooperi), desert almond (Prunus
fasciculata), ephedra (Ephedra spp.), liveforever (Dudleya spp.), agave
(Agave spp.), yucca (Yucca spp.), brickellia (Brickellia spp.),
rabbitbrush (Chrysothamnus spp.), euphorbia (Euphorbia spp.), buckwheat
(Erigonum spp.), shrubby alkali aster (Aster intricatus), thistle
(Cirsium mohavense), false sunflower (Enceliopsis nudicaulis),
alkaliweed (Cressa truxillensis), Montana pepperweed (Lepidium
montanum), and snakeweed (Gutierrezia spp.) [2,18,21].


SUCCESSIONAL STATUS : 
Obligate Initial Community Species

Succession in most desert communities requires a few centuries and in
creosotebush communities it could take several thousands of years for
stable communities to establish [25].  Succession in desert communities
has not been well documented for this reason.  

Bush encelia colonizes recently disturbed sites such as debris flows,
borrow pits, and drainage channels [23,25].  It is a short-lived invader
that increases its population size with a corresponding increase in the
level of disturbance [23].  Bush encelia maintains low numbers in small
natural disturbances within the mature community.  

In the Mojave desert, a borrow pit was excavated in 1970-71 to a depth
of 3.3 to 6.6 feet (1-2 m).  Large-scale seedling establishment by bush
encelia occurred following the excavation.  The heavily disturbed bottom
of the pit was colonized by a scrub community of low bushes dominated by
bush encelia [23].  The undisturbed area around the pit was dominated by
a creosotebush scrub community consisting of long-lived shrubs.  On
partially-disturbed sites on the sides of the borrow pit, bush encelia
was less common than in the more heavily disturbed sites.  The plant
density of bush encelia per hectare on: A-an undisturbed control area;
B-the heavily disturbed borrow pit bottom; and C-the partially disturbed
pit sides are as follows [23]:  
             
                     A                 B                    C
                    1979        1973  1975  1979     1973  1975  1979  

bush encelia         16         2446  2800  2837     1464  1514  1500



SEASONAL DEVELOPMENT : 
Flowering occurs from February to May in California [17] and from
January to September in Arizona [11].  Bush encelia is probably drought
deciduous, as are other species of Encelia [28].

Related categories for Species: Encelia frutescens | Bush Encelia