BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Artemisia cana ssp. bolanderi | Bolander Silver Sagebrush 



GENERAL BOTANICAL CHARACTERISTICS : 
Bolander silver sagebrush is an erect or spreading, thickly branched,
long-lived, evergreen shrub usually 12 to 24 inches (30 to 60 cm) tall
[1,30,35].  This species is both highly drought resistant and also able
to tolerate temporary flooding [4,11,31].  Bolander silver sagebrush is
the shortest of the three subspecies of silver sagebrush.  Branching
patterns produce crowns that are somewhat irregularly shaped.  Although
leaf morphology is highly variable, leaves are generally tapered at both
ends, unlobed, and candescent.  This subspecies is morphologically quite
similar to mountain silver sagebrush except for its characteristic dense
stem tomentum [26].  Although allelopathy has been documented in plains
silver sagebrush [9], its occurrence in this subspecies has not been
verified.  Plants of the silver sagebrush complex typically produce a
shallow to deep, well-branched root system [31].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Bolander silver sagebrush is generally thought to employ both sexual and
vegetative modes of reproduction.  Within the Artemisia genus, the
silver sagebrush complex is distinguished by its ability to resprout
following disturbance; however, resprouting abilities vary between the
three subspecies [37].  Bolander silver sagebrush plants can sprout from
the root crown and also readily layers [1,4].  Vegetative regeneration
would appear to be important on sites subjected to annual spring
flooding.  Reporting on the results of rangeland revegetation projects
along the east slope of the Sierra Nevada, Cornelius and Talbot [3]
found that mechanical control of Bolander silver sagebrush was most
effective when soils were plowed to depths of 6 to 8 inches (15 to 20
cm).  Severing plants several inches (approximately 5 cm) below the soil
surface or mowing caused crown sprouting in the majority of plants [3].
The role of seedling establishment remains unclear within the ecology of
this subspecies.  Sagebrush reestablishment occurred via the growth of
new or resprouted individuals on sites in Oregon where plants were
top-killed following prolonged spring flooding [4].  A number of studies
have reported on regeneration of plains silver sagebrush.  See Artemisia
cana ssp. cana regeneration slot for details.


SITE CHARACTERISTICS : 
Bolander silver sagebrush is restricted to internally drained, alkaline
basins scattered along the western edge of the sagebrush-grass region at
elevations ranging from 3,500 to 6,000 feet (1,067-1,830 m) [4,11,35].
Mean annual precipitation on these semiarid sites ranges from 8 to 10
inches (20-25 cm) [31].  In Oregon, plants apparently grade into
mountain silver sagebrush at elevations above 5,500 feet (1,677 m).

The silver sagebrush complex is unique among the Artemisia genus in its
ability to tolerate soil saturation and seasonal flooding.  Bolander
silver sagebrush is typically associated with sites that have standing
water for at least a month in the late winter or early spring; water
depths may reach 1 to 2 feet (0.3-0.6 m).  Occassionally the persistence
of standing water extends beyond the limits of this subspecies, and
plants die back to the root.  Resprouts and new individuals, however,
are able to regain coverages within approximately 3 years [4].  Most
soils are extremely clayey and are often derived from granite [26,35].
Summer drying produces wide, deep cracks in these clay soils into which
flaking surface layers readily slough [3].  This subspecies typically
occupies the relatively level terrain of alkaline basins, but stands
occasionally occur on cold, wet slopes between 7,000 and 8,000 feet
(2,134 and 2,440 m) in California [3].

Historically, vegetal cover has been sparse in basins dominated by
Bolander sagebrush.  Winward [35] suggests that this condition is more a
function of soil chemistry than an evidence of past abuse.  Seasonal
flooding of sites basically eliminates most plants common to
sagebrush-steppe communities.  Bolander sagebrush is typically the only
shrub present, and shrub interspaces remain essentially barren.  Moist
spring conditions create a lush herbaceous undergrowth; these plants,
however, are not maintained through the livestock grazing season.
Species adapted to such extremes of flooding and drying include mat muly
(Muhlenburgia richardsonis), spike rush (Eleocharis spp.), wire rush
(Juncus spp.), Baltic rush (Juncus balticus), Douglas sedge (Carex
douglasii), Newberry cinquefoil, showy downingia (Downingia elegans),
desert combleaf, tiny mousetail (Myosurus minimus), bottlebrush
squirreltail (Elymus elymoides), and cheatgrass (Bromus tectorum) [4].


SUCCESSIONAL STATUS : 
Mature, self-perpetuating stands of Bolander silver sagebrush are
indicative of climax conditions.  Plants are established during early
seral stages and coexist with later arriving species.  Apparently,
management activities which improve drainage on Bolander silver
sagebrush sites result in stands being invaded and in some instances
replaced by big sagebrush and rabbitbrush [3].


SEASONAL DEVELOPMENT : 
Phenological development of Bolander silver sagebrush is not well
documented.  The following generalized sequence has been described by
Beetle [1]:

	Immature flower heads        early August
	Flowering                    late August or early September
	Seeds ripe                   October

Related categories for Species: Artemisia cana ssp. bolanderi | Bolander Silver Sagebrush