BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Symphoricarpos occidentalis | Western Snowberry 



GENERAL BOTANICAL CHARACTERISTICS : 
Western snowberry is a native, deciduous, rhizomatous perennial shrub
that forms dense colonies by adventitious shoots from widely spreading
roots and rhizomes [19,50,56,77,130].  In Minnesota colonies from 3.3 to
660 feet (1-200 m) in diameter have been reported [94].  

Western snowberry is an erect shrub that grows from 2 to 4 feet (0.6-1.2
m) tall [50,62,130].  Leaves are 0.8 to 2.4 inches (2-6 cm) long and 0.4
to 1.4 inches (1-3.5 cm) wide [50,117].  The berrylike drupe contains 2
nutlets and ripens in the fall [38,112,127].  In Minnesota roots of
western snowberry penetrated to a depth of 5.2 feet (155 cm) in loamy
sand and rhizomes to a depth of 1.2 feet (35 cm) [94].  

A study in Minnesota showed that western snowberry stems ranged from 3
to 13 years old, with an average age of 7.2.  Rhizomes ranged from 5
to 40 years old, with an average age of 18.9 [94].  


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  Western snowberry reproduces by seed [22,35,38].  Seed is
pollinated by insects and dispersed by birds and mammals [38,94].  Seed
may be stored in dry sealed containers at 41 degrees Fahrenheit (5 deg
C) for up to 2 years with moderate loss of viability [127].  The seed is
surrounded by a stony endocarp which may offer some resistance to
germination.  Western snowberry has embryo dormancy; an afterripening
period is necessary for adequate germination.  Warm stratification at
room temperature for 3 to 4 months followed by cold stratification at 41
degrees Fahrenheit (5 deg C) for 4 to 6 months increases germination
[38,94,127].  In the laboratory a constant temperature of 50 degrees
Fahrenheit (10 deg C) produces a germination rate of 44.1 percent [94].

Vegetative:  Western snowberry reproduces vegetatively by root sprouts
and rhizomes [22,68,94].  According to Pelton [94], shoots from rhizomes
are more common than seedlings.  Adventitious shoots develop in the
spring and by the end of the first year they reach mature stem height
[94].  


SITE CHARACTERISTICS : 
Western snowberry is commonly found in riparian areas such as alluvial
floodplain terraces, upland ravines, swale-like depressions, and along
streams and rivers [48,54,56,57,130].  It is also common in open
deciduous woods, open prairies, rocky bluffs, pastures, and along
roadsides [50,62,94,114,127].  Western snowberry grows best on moist
soils with good drainage [18,34,62,112].  It will grow in semishaded
areas and on dry, exposed hillsides [54,114,127].  It grows best on loam
and sandy loam soils, but occurs on clay, clay loam, and gravelly
substrates as well [18,35,50,94,131].  Western snowberry is tolerant of
poorly drained soils and some flooding, but is intolerant of prolonged
flooding and permanently high water tables [54,56].

Elevations for western snowberry are as follows:

                     feet           meters         

Colorado          3,500-8,500     1,050-2,550     [35,57]
Montana           1,950-4,000       594-1,200     [56]
North Dakota        800-1,800       240-540       [140]   
South Dakota      4,125-7,000     1,250-2,100     [17,92]
Utah              5,030-6,270     1,525-1,900     [34,134]
Wyoming           7,525-9,900     2,280-3,000     [42]
Alberta           2,000-4,685       610-1,420     [4,137]


SUCCESSIONAL STATUS : 
Western snowberry is a generally shade intolerant species of sparse
woods, riparian sites, and open areas where there is often evidence of
past disturbance [15,40,79,130,131].  Western snowberry is a pioneer
species following broadcast burning and cattle grazing [8,56,130,131].
In the northern Great Plains western snowberry invades grasslands
[29,58,133]; it also occurs on stable portions of streambanks [20].
Western snowberry is a highly competitive species but can be suppressed
by taller woody plants such as green ash [20,56,130].

In the northern Great Plains, western snowberry forms dense, nearly
impenetrable thickets, often excluding other vegetation [20,56,94,130].
In Minnesota colonies of western snowberry range in size from 3.3 to 6.6
feet (1-2 m) to 165 to 247 feet (50-75 m) in diameter [94].  


SEASONAL DEVELOPMENT : 
Western snowberry flowering dates are as follows:

                 

Colorado         Jun-Aug      [35]
Great Plains     Jun-Aug      [50,114]
Illinois         Jun-Aug      [49]
Montana          June         [35]
New Mexico       May-July     [127]
North Dakota     Jun-July     [27,35]
Oklahoma         May-July     [127]
South Dakota     Jun-July     [39]
Wyoming          July         [35]

Fruit ripening occurs from August to September in the southwestern
states, and from September to October in the northern Great Plains
[114,127].  Seed dispersal occurs from September into early winter
[116].  
 

Related categories for Species: Symphoricarpos occidentalis | Western Snowberry