BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Xerophyllum tenax | Beargrass 



GENERAL BOTANICAL CHARACTERISTICS : 
Beargrass is a perennial, evergreen herb from the lily family with basal
leaves that form dense clumps or tussocks [81].  The linear leaves arise
from a short, woody rhizome and are scabrous, tough, and wiry [51].  If
pulled or stepped on, the grasslike leaves easily slide out of their
sheaths [58].  Any particular plant may not bloom for several years but
when it does it will produce a leafy flowering stalk that may be up to 6
feet (15 dm) tall with numerous small white flowers [51].  The sequence
of bloom is from the lowest flowers to the upper flowers resulting in a
knob of tight buds on top of the flower cluster [42].


RAUNKIAER LIFE FORM : 
   Geophyte


REGENERATION PROCESSES : 
Colonies of beargrass tend to bloom in 5- to 7-year cycles, possibly
when environmental conditions are right [58].  After fruit set, the
plants that bloom die.  However, normal vegetative reproduction of
offshoots has already occurred [42].  The fruit is a small three-lobed
capsule containing several seeds [42].  Seeds are 0.16 inch (4 mm) long
and average about 830,000 per pound (1,830,150/kg) [70,78].  The seed
needs cold stratification for germination [78].

Vegetative reproduction is by offshoots of the rhizome [42].  Beargrass
is usually considered to be long-lived because of its continual
production of offshoots [56].  Following disturbances, including mud
flows and debris slides, beargrass sprouts from rhizomes [2].  When
buried in tephra, which forms a new surface horizon, beargrass rhizomes
do not elongate and grow into the tephra.  Instead the plant continues
to grow from the old rhizome for at least the first year [6].


SITE CHARACTERISTICS : 
Beargrass is widely found as a understory dominant in cool western
spruce-fir forests.  It is also common under alpine larch (Larix
lyallii) and whitebark pine (Pinus albicaulis)-subalpine fir stands on
cold, rocky sites at upper timberline [7,34].  It is less common below
the subalpine zone [56].  Common understory dominants growing with
beargrass are huckleberries (Vaccinium spp.), grouse whortleberry
(Vaccinium scoparium), and sedges [22,18].

Rocky Mountain sites:  At the northeastern limit of its range in
Waterton Park, beargrass is found on moderate to steep south-facing
slopes on colluvial and morainal landforms with Engelmann spruce (Picea
engelmannii), subalpine fir, and whitebark pine [1,67].  Beargrass is
dominant with menziesia (Menziesia ferruginea) in subalpine forests near
the border between the United States and Canada [19].  Although they
grow together, beargrass favors more xeric conditions than does
menziesia [63].  In northern Idaho beargrass grows predominantly on
ridges and the upper portions of slopes [22,69].  Pure stands of
beargrass are found in treeless open parks with summer-dry soils on high
ridges and southerly slopes in northern Idaho and eastern Washington
[21].  In northern Idaho western redcedar (Thuja plicata) stands,
beargrass is most common at higher elevations [40].  In Montana,
beargrass may extend slightly from the forest into adjacent grasslands
[76].

West Coast sites:  In the Coastal Mountains of Oregon, beargrass is
found on steep sites on well-drained, frequently shallow, soils on
rugged, rocky topography near ridgetops [50].  It is often in areas with
active sheet erosion [50].  In the Oregon Cascades it may be dominant on
cold dry ridges and mountain tops from 4,700 to 5,800 feet (1,433-1,768
m) with soils that are poorly drained in spring and excessively well
drained in summer.  These sites often show no sign of having been
previously forested, but this community could be a prolonged seral stage
[49].  While beargrass grows on most sites in the western hemlock zone
of Oregon, Washington, and northern California, it has higher cover on
drier sites and grows well on talus or scree slopes [30,34,77].  In the
silver fir zone it does best toward the xeric end of the moisture
gradient [30].  Understories on relatively dry silver fir and mountain
hemlock sites may be depauperate with little growing besides beargrass
and huckleberry [33,34].  In Oregon's subalpine fir zone it does best on
upper south slopes and ridges [34].  Beargrass is common in the
mixed-evergreen and mixed-conifer zones on relatively cool, dry sites
under Douglas-fir (Pseudotsuga menziesii), grand fir, incense-cedar
(Libocedrus decurrens), sugar pine (Pinus lambertiana), tanoak, golden
chinquapin (Chrysolepis chrysophylla), and California black oak (Quercus
kelloggii) in southern Oregon, northern California, and the Siskiyou
Mountains [12,34,77].  In the pygmy forest region of California, it
grows in stands of Bishop pine (Pinus muricata) and Bolander pine (P.
bolanderi) [88].  Westman [88] considers beargrass a heliophilic
(sun-loving) plant which does well on these relatively unproductive,
open sites.

Soils:  Beargrass grows on a variety of soils and is able to grow well
on very shallow or rocky soils [30,43].  It does well on basaltic lava
flows in southern Washington but does not grow well on pumice [33,34].
On serpentine soils in the Siskiyou Mountains of Oregon and California,
beargrass grows most vigorously on submesic to mesic sites, while on
olivine gabbro soils, it is found on xeric to subxeric sites [89].  In
the Siskiyous it is the most useful indicator of small serpentine
outcrops [89].  It may dominate the herbaceous layer on serpentine and
other ultramafic soils under Douglas-fir, western white pine,
Port-Orford-cedar (Chamaecyparis lawsoniana), Jeffrey pine (Pinus
jeffreyi), huckleberry oak (Quercus vaccinifolia), and, at higher
elevations, white fir (Abies concolor) [10,47,89,94].  In Montana it
often occurs in association with volcanic ash soils [71].  In the Garnet
Mountains of Montana, where beargrass is prominent on soils formed from
granite and quartzite, essentially no beargrass occurs on soils formed
from limestone [37].  In Montana growth is poor on gravel, sand, and
dense clay; fair on clay; and good on sandy loam, loam, and clay loam
[27].  Its growth is poor on organic, saline, sodic, and sodic-saline
soils but good on acidic soils [27].


Elevation:  Elevational ranges in some western states are [27]:

                     Minimum                   Maximum
                   feet      meters         feet      meters

Montana            5,000     1,524          8,800     2,682
Wyoming            7,200     2,195          7,200     2,195
California         sea level                6,000     1,829


SUCCESSIONAL STATUS : 
Facultative Seral Species

Beargrass is moderately shade-tolerant [56,68].  It survives but seldom
blooms under a forest canopy.  In forest openings it grows vigorously
and blooms profusely [22,42,50,58].  In the subalpine fir, silver fir,
and mountain hemlock zones of Oregon, beargrass is a fire-resistant
species that becomes dominant in early succession [33,34].  In Rocky
Mountain forest stands with dense overstories, cover of beargrass will
be reduced with time [59].  Following severe disturbance, beargrass
seedlings may be abundant, but regrowth is slow [59].  Beargrass appears
to be very sensitive to competition from shrubs following disturbance
[56].  Frequently, growth and cover of established beargrass plants
declines for 2 to 8 years after canopy opening [56].  In the western
redcedar-western hemlock zone of Glacier Park, beargrass has very high
frequency in early and mid-seral communities but becomes rare in old age
forests [39].


SEASONAL DEVELOPMENT : 
Beargrass blooms in July in Wyoming.  In Montana buds are formed by May,
and full bloom begins in July and ends in August [27].  In California
flowering is from May to August [70].  In southern Oregon flowering
begins in late June, bloom continues and fruit set begins in the first
weeks of July, with fruiting continuing into September [75].  In
Washington during 1974, beargrass fruits were green on August 27.  By
September 10, half the fruits were brown and by September 25 the fruit
was opening and shedding seed.  On October 10 all the fruit was open
[96].

Related categories for Species: Xerophyllum tenax | Beargrass