BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Leymus cinereus | Basin Wildrye 



GENERAL BOTANICAL CHARACTERISTICS : 
Basin wildrye is an erect, native, cool-season, perennial bunchgrass.
It is robust, coarse, densely tufted, and salt tolerant.
[3,18,19,63,71,78].  It is the second largest native bunchgrass in the
western United States (only giant wildrye [Leymus condensatus] is
larger) [44].  Basin wildrye forms wide, distinct bunches, with basal
diameters of mature plants often reaching 2 to 3 feet (1 m) [19].

Basin wildrye is typically nonrhizomatous but sometimes produces short,
thick rhizomes [5]; in the Pacific Northwest, Hitchcock and others [36]
reported that plants commonly possess culms or groups of culms connected
by short rhizomes.  On productive sites in the Great Basin, basin
wildrye may attain heights of 6 to 10 feet (1.8-3 m) [76].  Culms are
erect, stout, solid, and somewhat woody, and typically range from 2.3 to
7 feet (70-210 cm) in height [4].

The inflorescence is an erect, compact, dense spike [75].  Barkworth and
Dewey [4] reported that spikes range from 4 to 11.6 inches (10-29 cm) in
length with 16 to 35 nodes and two to seven spikelets per node.
Although overall plant color is typically bright green, some individuals
are covered or whitened with a bloom [4].  The coarse, wide, flat basal
leaves commonly reach lengths of 18 inches (45 cm) [39,78].  Plants have
an extensive, coarse, fibrous root system [76,78].

Basin wildrye exhibits considerable ecotypic variation [44,56,86].
Variable traits include coarseness, growth form, color, forage yield,
and rate of seed germination [21,72,78].  Robust basin wildrye plants
closely resemble giant wildrye, which is a more strongly rhizomatous
species of coastal California [36].


RAUNKIAER LIFE FORM : 
   Hemicryptophyte


REGENERATION PROCESSES : 
Basin wildrye reproduces through seed and vegetatively [71,75].
Vegetative expansion via tillering appears to be the predominant means
of regeneration [54].  Frequently plants also form short, thick rhizomes
[4,19,] which connect culms or groups of culms [36].

Plants typically produce a very high fertile:vegetative stem ratio [55].  Krall and
others [42] estimated that reproductive stems comprised up to 90 percent
of the tillers initiated by mature plants on sites in Montana.  The
following years' tillers are usually initiated in June with growing
points elevated approximately 1 inch (2.5 cm) during August [55].  Seed
set in this species is apomictic (without fertilization) [44].

Despite high seed production potential, the yield, viability, and
germination of seeds from native stands in the central Great Basin is
characteristically low.  Germination is often limited by low soil matric
and osmotic potentials and possibly by toxic concentrations of specific
ions [65].  As a result, basin wildrye has rather specific requirements
for successful germination and establishment.  Ecotypes vary widely in
their germination requirements, with certain populations exhibiting
discontinuous germination [52,86].

Basin wildrye is able to germinate and emerge at low osmotic potentials
[16,31,86].  In one study, seeds under no osmotic stress germinated best
at 59 degrees Fahrenheit (15 deg C), but germination rarely exceeded 35
to 40 percent [86].  Under reduced osmotic potentials, germination had a
strong negative correlation with the electrical conductivity and
sodium-absorption ratios of the surface soils where the seeds had been
produced.  In addition, seedling emergence and growth in a
saline/alkaline soil were better with seeds produced from plants growing
on nonalkaline upland soils than from those growing on saline/alkaline
soils.  The following senerio was suggested as a possible explanation
for the adaptive value of this inverse relationship.  Perhaps during the
late summer, seedbeds are too dry to support germination and when fall
rains occur, seedbed temperatures may be too low.  Seeds then remain
dormant until the following spring when seedbed temperatures rise and
snowmelt dilutes the salt concentrations to the point where germination
can occur [86].  

High spring precipitation favors seedling establishment on saline soils
by maintaining higher total soil water potentials and by softening the
vesicular crust of interspaces for a short time [31,64,76].  In
greasewood/salt rabbitbrush/basin wildrye communities in Nevada, Roundy
and others [64] observed natural seedling emergence of basin wildrye
only in the crevices and cracks of salt-desert soils.  The cracks in the
crust may be important safe sites for seed germination and emergence.
Seeds are able to emerge unrestricted from lower soil depths where the
soil water potential is much higher and fluctuates less than at the soil
surface [64].

`Magnar', a recently developed cultivar of basin wildrye, exhibits
better overall germination and seedling vigor than native stands [65].
Evans and Young [27] reported that over a 4-week period, germination of
`Magnar' was 82 percent at moderate seedbed temperatures (around 68
degrees Fahrenheit [20 deg C]); 52 to 71 percent of the total
germination occurred by the end of the first week.  

Once established, basin wildrye is a good competitor unless subjected to
intense competition from exotic herbs [84].  Seeded stands typically
establish within 2 to 3 years [78].  Presumably most seeds are dispersed
within close proximity to the parent plant, although long-distance seed
disperal undoubtedly occurs.  Although dispersal vectors were not
mentioned, Walker and Brotherson [76] reported that basin wildrye
invaded badger diggings within mountain big sagebrush communities where
it was largely absent from the understory.


SITE CHARACTERISTICS : 
Basin wildrye has a wide range of adaptation, occurring from
saline/alkaline valley bottoms and among sagebrush to aspen woodlands
[19,36,49,56].  Basin wildrye is better adapted to areas with wet
winters and dry summers than to areas with dry winters and wet summers.
Although native to the Great Plains, this species is generally more
abundant in the valleys of the northern Rocky Mountains and the northern
portion of the Intermountain Region [73].  Wasser [78] reported that
basin wildrye is adapted to MAP (mean annual precipitation) zones of
below 10 inches (25 cm) to over 20 inches (50 cm).  Optimal growth
occurs on overflow and subirrigated range sites where MAP zones exceed
15 inches.  Apparently moisture-concentrating abilities of a site are
more controlling than MAP [78].

Basin wildrye reaches its greatest prominence in moist or wet
saline/alkaline conditions in valley bottoms and also in the moderately
dry, rich soils of low, mountain grasslands and upper sagebrush zones
[75].  In northern Nevada basin wildrye basin, wildrye is equally well
adapted to highly saline/alkaline soils and to upland nonsaline/alkaline
soils, although populations growing in these drastically different
environments do not exhibit morphologically distinct ecotypes [86].

Basin wildrye can grow in a wide range of soil types but grows best in
silty or clayey soils [34]; it is somewhat tolerant of sandy or clayey
textured soils [21,78].  Basin wildrye is generally intolerant of
shallow soils and usually exhibits reduced productivity on deep, coarse,
sandy soils [69].  

Basin wildrye is tolerant of a range of moisture conditions including
fair soil drainage; short-term winter flooding; the water table
intermittently in the top 1 foot (30 cm) of soil; and the partial shade
of woodlands [78].  This grass is typically found along streams,
gullies, ravines, foothills drainages, roadsides, prairie flats or
hillsides, open woodlands, and sand dunes [18,34,36].

Throughout it distribution, basin wildrye is most often associated with
saline and/or alkaline lowland sites, typically floodplains and basin
bottoms, which have more effective moisture than adjacent areas
[20,39,44,63,69].  These sites are characterized by fine-textured,
saline/alkaline soils, shallow water tables, and are often subjected to
short-term seasonal flooding [39,57,78].  In salt desert communities,
basin wildrye grows well in soils with low to moderately high salinity
(Ece 4 to 15 mmhos) and is most productive where the soil is wet but not
saturated through the summer; generally the water table is within 8.2
feet (2.5 m) of the surface [63].  Common salt desert shrub associates
include greasewood and salt rabbitbrush; inland saltgrass (Distichis
stricta) is common in the understory.

On better drained, bottomland sites, basin wildrye occurs as stringers
within both broad and narrow drainages [2,20] and also as patches near
seeps and springs [35].  Overstory associates on lowland sites include
the following:  basin big sagebrush, mountain big sagebrush, threetip
sagebrush (Artemisia tripartita), low sagebrush (A. arbuscula), Bolander
silver sagebrush (A. cana spp. bolanderi), and narrow-leaved cottonwood
(Populus angustifolia) [21,36,44,78].

On upland sites, basin wildrye is found on gravelly to sandy areas
within sagebrush and open woodlands [4].  Culver [20] reported that in
sagebrush/bluebunch wheatgrass associations in Oregon, the presence of
basin wildrye is highly correlated with mounded microrelief.  Mound
soils were approximately 6 feet (1.8 m) deep, loamy, and exhibited a
weakly developed profile.  Walker and Brotherson [76] reported that
basin wildrye usually grows on elevated microtopography within mountain
big sagebrush communities in Utah.  On these sites the occurrence of
basin wildrye was positively correlated with disturbance, typically
badger diggings.  Soils of wildrye sites had higher leached potassium
concentrations than adjacent sagebrush/grassland sites.  Hironaka and
others [36] speculated that basin wildrye is able to tap watertables
that are often more than 2 feet (6 dm) deep on upland mountain big
sagebrush/basin wildrye habitat types in Idaho.  Common upland
associates include mountain big sagebrush, mountain brome (Bromus
carinatus), bluebunch wheatgrass (Pascopyrum smithii), western
wheatgrass.

Elevational ranges vary from 1,000 to 2,000 feet (305 to 610 m) in
drainage basins to over 8,000 or 9,000 feet (2,439 or 2,744 m) in the
mountains [78].  Elevational ranges for differnet states are listed
below [10,20,24,48,51,74]:

        from  4,600 to 10,00 feet (1,402-3,049 m) in CO
              3,200 to 6,700 feet (976-2,043 m) in MT
              5,600 to 8,000 feet (1,707-2,439 m) in NV
              4,000 to 4,800 feet (1,220-1,463 m) in OR
              5,000 to 6,500 feet (1,524-1,982 m) in UT
              3,000 to 7,800 feet (915-2,378 m) in WY


SUCCESSIONAL STATUS : 
Facultative Seral Species

Self-perpetuating stands of basin wildrye are indicative of climax or
late seral conditions in numerous saline grassland or shrubland
communities throughout the Great Basin [2,35,48,50].  In Oregon, big
sagebrush/basin wildrye associations are considered to be an edaphic
climax because the occurrence of basin wildrye is typically associated
with site conditions related to either greater effective rooting depth
or greater effective soil moisture than in adjacent areas.  Studying
postfire successional patterns of sagebrush-grassland communities in
southeastern Idaho, Humphrey [38] reported that although basin wildrye
is present on 25- to 35-year-old burns, abundances are reduced from
those of mid-successional stages.  Once established, plants are strong
competitors and effectively suppress associates and herbaceous weeds
[78].  Basin wildrye, however, is very susceptible to grazing damage
from intense utilization of early spring and fall regrowth [44,55].
Basin wildrye generally survives fire to become part of the early seral
postfire community [82,89].


SEASONAL DEVELOPMENT : 
The seasonal growth pattern of basin wildrye differs from that of many
cool-season grasses in that phenological events occur over an extended
period.  On sites in south-central Montana, winter dormancy was broken
in early March; the first leaves appeared between March 10 and March 20
[42].  At this time growth is generally slow due to cool temperatures.
Floral growing points did not protrude above the soil surface until the
early boot stage on May 23.  From this time until June 5, heads in the
boot elongated from 0.5 to 5.3 inches (1.2-13.2 cm) [42].  Basin wildrye
undergoes a prolonged vegetative stage which delays other phenological
events; thus despite its early spring growth, it is classified as a
late-maturing species.  In Montana, rapid stem elongation typically
occurs during June [42,54].  New tillers for the following season are
also initiated in June [54].  Although growth is relatively slight
during June and July, between August 1 and August 20, tillers grow an
average of 1 inch (2.5 cm); growth then terminates until the following
spring.  The phenological development of basin wildrye at Bridger,
Montana, is presented below [42]:

    Phenological stage            Date (1966)
         vegetative               April 28 - May 26
         boot                     June 2
         late boot                June 9
         heading                  June 16
         headed                   June 23
         blooming                 June 30
         milk                     July 7
         soft dough               July 14-21
         hard dough               July 28
         seed ripe                August 4
         seed shattering          August 11-28
         herbage curing           August 25-Oct 13

The phenological development for basin wildrye on the Saylor Creek
Experimental Range in southern Idaho from 1960 to 1969 was reported as
follows:

	Phenology              Date
	growth begins          early to mid April
    	flower stalks start    mid to late May
	anthesis               mid to late June
	plant dry              early to late August
	fall regrowth begins   late August to late October

Perry and [54] have studied seasonal trends in carbohydrate reserves of
basin wildrye.  Results indicate that reserves increase rapidly during
the later part of May during the late vegetative stage when growing
points are at or near the soil surface.  Levels of total available
carbohydrates (TAC) are severely drained in June at which time growing
points are elevated from ground level to near maximum height.  After
this time, TAC levels gradually increase through the summer except for a
slight decline in mid-August associated with the following years's
tiller development.

Related categories for Species: Leymus cinereus | Basin Wildrye