BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Bromus carinatus | California Brome 



GENERAL BOTANICAL CHARACTERISTICS : 
California brome is a cool-season perennial bunchgrass.  It is a mid- to
tall grass; the erect culms are 1 to 4 feet (0.3-1.2 m) high at maturity
[16,32,35,79].  The inflorescence is an open panicle, 4 to 12 inches
(10-30.5 cm) long, with erect to spreading branches.  Lemmas have short
awns, about 0.2 to 0.3 inch (5-7 mm) in length [34,79].  Roots are deep
and wide-spreading.  California brome seedlings grown on gravelly clay
with a subsoil of clay had a horizontal root spread of 28 inches (70 cm)
and a vertical root spread of 28 inches (70 cm) at the end of the first
growing season [3].

Life span of California brome is about 3 to 5 years [34].


RAUNKIAER LIFE FORM : 
   Hemicryptophyte


REGENERATION PROCESSES : 
California brome reproduces by seed and by tillering [79].  It is both
self-pollinating and outcrossing [55]; self-pollination is more common
than outcrossing [35].  Harlan [29] found that California brome
collected from various locations in California was facultatively
cleistogamous.  In the greenhouse, both open-pollinating and
cleistogamous florets were produced on the same plant when soil was dry
during flower development.  Plants produced only open-pollinating
florets when soil was moist during flower development.  Both
open-pollinating and cleistogamous florets are commonly found on the
same plant in California fields [35].

Germinative capacity of fresh California brome seed is 85 to 90 percent
under laboratory conditions.  It is widely reported that seeds require
fluctuating temperatures and light to germinate [24,38,87].  Plummer,
however, [63] found that either constant temperature of 85 degrees
Fahrenheit (30 deg C) or room temperature resulted in germination rates
comparable to those obtained with fluctuating temperatures.

It is unclear whether long-term seedbanking is an important regeneration
strategy for California brome.  Steele [75] stated that most California
brome seedlings in northern Idaho establish from seed shattered the
previous fall.  Fulbright [24] reported that California brome seed is
viable for only 3 to 4 years.  Viability may be longer, however.  On a
remnant valley grassland-coastal prairie mosaic in San Francisco,
California, native species were planted and exotics were controlled by
clipping.  Although California brome was not among the native species
planted, California brome seedlings appeared after the restoration
treatment.  Since California brome had been absent from the site for at
least 15 years, Pitschel [62] thought it most likely established from
soil-stored seed.

Seedlings attain height and root biomass rapidly [24,32,73].
Twenty-eight days after emergence in the greenhouse, California brome
seedlings averaged 61 roots each with an average total root length of
11.2 inches (28 cm).  Shoot length 28 days after emergence averaged 2.8
inches (7 cm) [63].  California brome often produces seed in its first
growing season [86], although it may not reproduce until 2 or 3 years of
age on some sites [16].


SITE CHARACTERISTICS : 
California brome occurs on mountain slopes, ridgetops, valleys, meadows,
and waste places.  It is adapted to moderately moist to dry soils [79],
and is most common in areas receiving 16 to 30 inches (410-760 mm) of
annual precipitation [73].  In the West, it is more common in dry
cordilleran regions than in the Pacific Northwest.  In British Columbia,
occurrence increases with increasing temperature and continentality and
decreases with increasing precipitation [46].  California brome is
reported from a broad spectrum of moisture regimes, however.  In
Redwoods National Park, California, California brome occurs on sites
varying from dry slopes and rock outcrops to stream channels [80].  In
Arizona, it occurs on moist mountain meadows but also occurs on dry
hills [45].

California brome grows in all soil textures.  Best growth is attained on
medium-textured or loamy soils [24,79].  California brome tolerates
soils in the pH range of 5.5 to 8.0 [73].

Elevational ranges of California brome are as follows:

Arizona - 5,500 to 9,500 feet (1,650-2,850 m) [45]
California - sea level to 10,000 feet (3,000 m) [67]
Colorado - 5,000 to 11,000 feet (1,500-3,300 m) [31,34]
Utah - 3,036 to 10,560 feet (920-3,200 m) [86]


SUCCESSIONAL STATUS : 
California brome occurs in early seres in forested communities
[46,75,76] and in all stages of succession in shrub steppe and grassland
communities [21,22,28].  It requires nearly full to full sunlight
[46,75].

California brome pioneered on mud flows on the slope of Mount St. Helens
in the first 4 years after the 1980 eruption [19].

Numerous studies report California brome in secondary succession.  It
was a component of the initial postfire community following
stand-replacing fire in twoneedle pinyon-Utah juniper (Pinus
edulis-Juniperus osteosperma) in Mese Verde National Park, Colorado
[22].  Hann [28] listed California brome as a component of the pinegrass
(Calamagrostis rubescens) early phase of the Douglas-fir/twinflower
(Pseudotsuga menziesii/Linnaea borealis) habitat type of western
Montana.  In mountain big sagebrush/elk sedge habitat types of southern
Idaho, California brome replaces elk sedge on disturbed soils or when
elk sedge fails to regenerate [36].


SEASONAL DEVELOPMENT : 
Growth begins in early spring [79], with most growth occurring in early
summer [34].  Fruits mature in mid- to late summer [24].  In California,
seeds ripen in May and June at low elevations; at high elevations, seeds
ripen and are cast by late August [67].

Phenological development of California brome in the Wasatch Mountains of
northern Utah ranged as follows from 1925 to 1934 [14].

       Event                      Date 
____________________     ________________________
snow disappearance       April 23 - June 15 
flower buds evident      June 9 - July 6
flowerstalks evident     June 24 - July 21
flowers in bloom         July 5 - August 10
seed ripe                August 8 - September 20
seed dispersed           September 9 - October 11          

Related categories for Species: Bromus carinatus | California Brome