BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Rhamnus purshiana | Cascara 



GENERAL BOTANICAL CHARACTERISTICS : 
Cascara is a deciduous, erect, tall shrub or small tree.  It can attain
a height up to 33 feet (10 m) at maturity, but becomes smaller in size
and bushier along its southern distribution [29].  West of the Cascades,
it develops a single trunk 8 to 12 inches (20-30 cm) thick, 20 to 35
feet (6-10.7 m) tall.  It has greenish-yellow flower petals
approximately 0.12 to 0.16 inch (3-4 mm) long [23].  Cascara has a
purplish-black drupe about 0.3 inch (7.5 mm) in diameter, containing
several seeds [5,20].  Cascara is very tolerant of shade [1].  The
leaves are oblong, 3 to 5 inches (7.5-12.5 cm) long, and have 10 to 12
pairs of prominent parallel veins arising directly opposite each other
on the midrib.  The leaf buds have no scales [12,27].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Cascara usually reproduces by seed.  It can also spread by layering and
can sometimes be propagated by cuttings.  Cascara will coppice after
being stripped of bark and cut down [11,29].

Seeds:  Cascara generally produces 20 pounds (18 kg) of seeds per 100
pounds (90 kg) of fruit.  Cleaned seeds range from 5,000 to 19,000 seeds
per pound (4,500-17,100 kg), with an average of 12,300.  Recommended
sowing depth is 1 inch, with seedbed shading [13].  Birds are the
predominant distributors of cascara seeds [1].

Morphological characteristics of cascara fruit from Rainbow Creek
Research Natural Area, southeast Washington are as follows [24]:

                                      Mean
                                     ------
Fruit Diameter (mm)                   11.60
Fruit Mass (mg)                      796.80 
Pulp Dry Mass (mg)                   126.10
Number of Seeds per Fruit              3.00
Fresh Seed Mass per Fruit (mg)       165.20
Fresh Pulp Mass (mg)                   3.80


SITE CHARACTERISTICS : 
Cascara generally grows on lower mountain slopes [1].  It may also
inhabit moist canyons on the east slope of the Cascades.  In Oregon,
cascara is generally a moist-site indicator [2].  It is commonly found
with red alder (Alnus rubra) on moist bottomlands but is rarely abundant
[1].

Site characteristics from southern Oregon Cascade Mountain Province
where cascara is found as a forest nominal component are as follows [2]:

                          Range of Means
                          --------------
Elevation (ft):            2,447 - 4,232
Slope (%):                  13.0 - 53.0
Soil Depth (in):            34.6 - 46.7
Rooting Depth (in):         39.3 - 50.0
Mean Annual Temp. (F):      43.9 - 48.8
Max. Month Temp. (F):       77.5 - 84.7
Mean Annual ppt (in):       36.7 - 67.5
Dry Season ppt (in):         6.0 -  8.8
Litter (%):                 70.7 - 98.7
Moss (%):                    2.3 - 45.2
Bareground (%):              0.2 -  4.0
Gravel (%):                  0.3 -  3.8
Rock (%):                    0.4 -  6.1
Bedrock (%):                 0.0 -  3.8



SUCCESSIONAL STATUS : 
Cascara has not been cited as a dominant species in any forest habitat
type described for the Pacific Northwest.  Being shade tolerant, it is
often found in the understory of second-growth forests [1].  Therefore,
its primary role seems to be that of a long-lived invader species.


SEASONAL DEVELOPMENT : 
Major phenological activities of cascara in northern Idaho are as
follows [22]:

       Bud      Leafing     Stem                Fruit   Leaf Color  Leaf
Year  Swell       Out      Growth    Blooming   Growth    Change    Fall
------------------------------------------------------------------------
1971  NA-4/27   5/4-5/19  5/11-7/21  5/26-6/9   6/18-NA    9/30      NA
1972  4/19/5/6  5/6-6/2   5/19-7/12  5/22-6/13  6/20-NA    10/9      NA
1973  NA-4/23   5/2-6/4   5/2-7/4    5/28-6/12  6/19-NA    10/2      NA

  

Related categories for Species: Rhamnus purshiana | Cascara