BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Crataegus douglasii | Douglas Hawthorn 



GENERAL BOTANICAL CHARACTERISTICS : 
Douglas hawthorn is a large shrub or small tree ranging from 3.5 to 13.0
feet (1-4 m) tall and possessing straight, strong thorns 0.5 to 1.0 inch
(1.00-2.50 cm) long.  Leaves are generally 1.5 to 2.5 inches (3-6 cm)
long, broad, and serrated at the tip.  Blackish, smooth fruits are about
0.5 inch (1 cm) long.  Numerous mosses and lichens are present upon the
entire bark system [4,19]

Douglas hawthorn stems are usually clustered from the base or from a
point just above the soil surface.  Shade-killed lower limbs persist on
the stem, creating large, dense thickets [11].  Stems are very flexible
and have been shown to withstand avalanche impact pressures of up to 10
tons per square meter [8].



RAUNKIAER LIFE FORM : 
   Phanerophyte
   Cryptophyte


REGENERATION PROCESSES : 
Douglas hawthorn produces many fertile seeds.  Following the removal of
aboveground stems, Douglas hawthorn will resprout and sucker from the
root system [17].

Seeds:  The average amount of cleaned Douglas hawthorn seeds collected
from Washington, Idaho, and Oregon was 22,600 per pound (10,170/kg).
Cultivation of Douglas hawthorn seed requires pregermination treatments
to break embryo dormancy.  Scarification in acid for 0.5 to 3.0 hours,
followed by 84 to 112 days of cold treatment at 41 degrees Fahrenheit (5
deg C) will generally yield 50 to 80 percent germination [4].

Morphological characteristics of Douglas hawthorn fruit from Rainbow
Creek Research Natural Area, southeastern Washington, are presented
below [29]:
                                  Mean         Standard Error
                                 ------       ----------------
Fruit Diameter (mm)              11.11              0.08
Fruit Mass (mg)                 634.38             12.72
Pulp Dry Mass (mg)              109.43               NA
Number of seeds per Fruit         4.78               NA
Fresh Seed Mass per Fruit (mg)   83.74               NA
Fresh Pulp Mass (mg)              6.58               NA

(n=100)


SITE CHARACTERISTICS : 
Douglas hawthorn can be found at lower elevations from 2,200 to 5,400
feet (670-1,645 m).  It typically forms small, dense, impenetrable
thickets in irregular patterns across open areas or along moist riparian
sites [3,17].  Douglas hawthorn is also found on steep, uncultivated
slopes [11].  In west-central Montana, it is common on mesic valley and
montane sites [22].  It can be found on all exposures, including dry
southern exposures, where moisture levels are sufficient [11].

Soils:  Douglas hawthorn generally occurs on deep, moist, fine-textured
soils.  Soils under Douglas hawthorn stands were found to be cooler and
wetter than adjacent steppe communities in eastern Washington [11].
These stands typically provide 100 percent soil cover, thus increasing
soil moisture by decreasing surface soil temperatures [10].  Kauffman
and others [20] found soils beneath Douglas hawthorn in northeastern
Oregon to have a thick A-horizon, 13 to 17 inches (33-43 cm), with
evidence of mottling.  Depth to the parent material varied from 27 to 40
inches (69-100 cm), but was usually less than 30 inches (75 cm).


SUCCESSIONAL STATUS : 
Douglas hawthorn predominantly occurs as an understory species (see
Habitat Types); however, it can be found in pure stands.  Typically,
Douglas hawthorn does not occupy disturbed sites [17].  Disturbance from
fire, agricultural cropping, or flooding seems to inhibit proliferous
growth [11].  Butler [7], however, found Douglas hawthorn present on
frequently disturbed areas such as avalanche shoots in Glacier National
Park, Montana.


SEASONAL DEVELOPMENT : 
Specific information concerning the seasonal development of Douglas
hawthorn is not available.  Douglas hawthorn fruits are considered ripe
when they are black and lustrous.  In Oregon fruit was dispersed from
August 16 to 31, and in Washington from July 15 to 30 [35].

Related categories for Species: Crataegus douglasii | Douglas Hawthorn