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



GENERAL BOTANICAL CHARACTERISTICS : 
Plains silver sagebrush is an erect, freely branching, native,
long-lived, aromatic, deciduous, rounded, canescent shrub usually
growing 3 to 5 feet (0.9 to 1.5 m) in height.  As its name implies,
silver sagebrush appears white in color when compared with other
Artemisia species.  Older branches have dark-brown fibrous bark; younger
branches are covered with a dense white to yellowish-green tomentum.
Unlike the other two subspecies which exhibit wide variations in leaf
morphology, leaves of the plains subspecies are generally entire and
densely, silky canescent [1,22].  Allelopathy has been documented in
this subspecies [15].


RAUNKIAER LIFE FORM : 
   Phanerophyte
   Geophyte


REGENERATION PROCESSES : 
Throughout its range, plains silver sagebrush regenerates both sexually
and vegetatively.  As a species the silver sagebrushes are distinguished
within the Artemisia genus for resprouting following disturbance.
Vegetative regeneration is apparently the primary mode of reproduction.
In fact, Harvey [15] found seed-derived plants only on severely
disturbed sites, and even these plants were mixed with sprouts
originating from undamaged roots.
 
Plants are capable of spreading extensively through layering, rhizomes,
and root sprouting (roots producing adventitious sprouts) [1,26].
Layering occurs almost exclusively in habitats subjected to periodic
flooding where vegetative branches become covered with silt.  Root
sprouting also occurs on these sites and is a commonly employed strategy
elsewhere.  Harvey [15] excavated plains silver sagebrush plants in
Montana and observed the tap root of one plant extending hortizontally
for 29.5 feet (9 m) before turning downward into the B and C horizons.
This root remained within 2 inches (5 cm) of the soil surface and had 14
sprouts arising from it.  All of these sprouts had grown adventitious
roots and were apparently self-supporting.  Plains silver sagebrush
universally exhibits some degree of rhizomatous growth, even at the
seedling stage [36].

Plains silver sagebrush produces numerous achenes in October or
November.  In most cases the majority are dispersed close to or under
the parent plant canopy.  However Walton and others [37] report an
instance of seeds being evenly dispersed up to 9.8 feet (3 m) from the
parent plant, but beyond this point seed dispersal dropped sharply.
Seeds of this species possess a mucilaginous seed coat indicating that
animals may act as dispersal agents.  Upon contact with water, the seed
coat becomes gelatinous which enables the seed to adhere to soil
particles.

While seed production is prolific (54,000 seeds per plant), very few
seeds germinate and survive beyond the 1st year.  Soil moisture is the
primary controlling factor in successful seedling establishment.
Consequently, favorable years for successful establishment are often
erratic.  In Montana only 1.2 percent of field-planted seeds germinated
and of the emerged seedlings, only 11 percent became established.  Seeds
of silver sagebrush are nondormant and do not require stratification for
successful germination.  Harvey reported an optimum germination
temperature of 57 degrees F (14 degrees C), although a temperature of 64
degrees F (20 degrees C) was determined as optimal when the effects of
light and osmotic pressure were also considered [36].  Seed maturity
appears to influence seed germination, with late season seed collections
having a higher germination rate.

Seedling emergence is influenced by the depth at which seeds are buried.
Previously soil depths of 0.08 inch (2 mm) were considered optimal for
silver sagebrush.  Data from field studies in Montana indicate that more
seedlings were produced from seeds planted under 0.2 inch (5 mm) of soil
than from trials at 0 and 0.6 inch (0 and 15 mm).  However, overall
seedling survival was greatest in seeds planted at 0.6 inch (15 mm).


SITE CHARACTERISTICS : 
Plains silver sagebrush is widely but sparsely distributed throughout
the northern Great Plains at elevations ranging from 4,000 to 7,000 feet
(1,200 to 2,100 m).  Plants usually occur on deep loam to sandy soils of
the region [30].  This species is most commonly found scattered along
well-drained uplands; however, greater numbers and sometimes local
dominance occur on alluvial flats and terraces of valley bottoms and
basins [3].

Soils supporting plains silver sagebrush are characterized by a
well-drained profile.  This relationship is so predominant that in most
cases the occurence of silver sagebrush serves as an indicator of
well-drained, coarse-textured soils [17].  Plant heights range from a
few inches (5 cm) on clay soils to approximately 2 feet (60 cm) on sandy
soils [7].  Upland sites usually have a sandy fraction; coarse, alluvial
deposits comprise bottomland sites.  Many of the lowland sites are also
subjected to periodic flooding, erosion, and deposition.  In fact,
plants grow preferentially on sites influenced by high water tables,
especially where roots can intersect the water table for at least part
of the growing season.

Sites dominated by plains silver sagebrush have lower levels of P, K, N,
organic matter, and cation exchange than adjacent big sagebrush soils
[16].  Harvey [15] observed plains silver sagebrush to be more deeply
rooted than Wyoming big sagebrush on sites where they occurred together.

Elevational ranges for some western states are presented below [9].

	  from 5,000 to 10,000 ft (1,524 to 3,059 m) in CO
               2,500 to  5,500 ft (762 to 1,677 m) in MT
               4,500 to  7,500 ft (1,372 to 2,287 m) in WY


SUCCESSIONAL STATUS : 
Plains silver sagebrush is an significant ecological dominant over much
of the Missouri Plateau and peripheral areas east of the Continental
Divide.  Mature stands are an indicator of climax conditions.  Plants
are established during early seral stages and coexist with later
arriving species [37].


SEASONAL DEVELOPMENT : 
Phenological development of plains silver sagebrush follows the general
pattern for most woody Artemisias.  New growth begins in April or early
May, flowering takes place in September, and seeds ripen in October and
November [1].  Apparently temperature significantly influences the
timing of early events; middle and late stages are influenced by both
temperature and moisture [15].  Preliminary data on water relations in
plains silver sagebrush indicates that as plant moisture stress becomes
greater, plant phenology advances [40].  In eastern Montana aphid
infestations are often frequent and severe in this subspecies.  Some
years entire stands have been essentially devoid of flowers.

Detailed data from Montana for sites below 5,900 feet (1,800 m) are
presented below [15]; similar results have been reported by White and
Currie [40].  In general, plants above this elevation initiated early
stages 2 to 3 weeks later; mid to late stages were initiated
approximately 2 weeks earlier.

Phenological Stage                  Month
apical bud enlargement              April
apical twig elongation              April to mid-May 
lateral branch bud enlargement      mid-May to late June
apical growth ceases (vegetative)   June
lateral branch elongation           June
lateral growth ceases (vegetative)  late June to early July 
floral branch elongation            late June to mid-July
floral buds enlarging               mid-July to mid-August
anther development (buds yellow)    August
anthesis                            mid-August to mid-September
cypsella (fruit) development        mid-September to mid-October
dissemination initiated             mid-October
dissemination completed             mid-October to mid-November
winter dormancy                     mid-November to April

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