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Wildlife, Animals, and Plants
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Introductory
SPECIES: Yucca glauca | Soapweed Yucca
ABBREVIATION :
YUCGLA
SYNONYMS :
Yucca angustifolia
Yucca arkansana
SCS PLANT CODE :
YUGL
YUGLG2
YUGLG
COMMON NAMES :
soapweed yucca
soapwell
beargrass
Great Plains yucca
soapweed
small soapweed
TAXONOMY :
The currently accepted scientific name of soapweed yucca is Yucca
glauca Nutt. [11,24]. Commonly recognized varieties are:
Y. glauca var. glauca [11,24]
Y. glauca var. mollis Engelm. [11,24]
Y. glauca var. gurneyi McKelvey [24]
Soapweed yucca hybridizes with Spaniah bayonet (Y. harrimaniae),
Buckley's yucca (Y. constricta), Spanish dagger (Y. arizonica),
Thompson's yucca (Y. thompsoniana), banana yucca (Y. baccata), soaptree
yucca (Y. elata), narrowleaf yucca (Y. angustissima), and Bailey's yucca
(Y. baileyi) [45,46]. Webber [45] refered to a swarm made up of
soapweed yucca, narrowleaf yucca, Bailey's yucca, and Buckley's yucca,
which is characterized by much interbreeding and plants with variable,
intermediate morphological characteristics.
LIFE FORM :
Shrub
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
Soapweed yucca is listed as vulnerable in Alberta and Saskatchewan [49].
COMPILED BY AND DATE :
D. Tirmenstein, March, 1989.
LAST REVISED BY AND DATE :
NO-ENTRY
AUTHORSHIP AND CITATION :
Tirmenstein, D. 1989. Yucca glauca. In: Remainder of Citation
DISTRIBUTION AND OCCURRENCE
SPECIES: Yucca glauca | Soapweed Yucca
GENERAL DISTRIBUTION :
Soapweed yucca grows throughout much of the Great Plains from Texas and
Arizona northward to Montana and the Dakotas [23,26]. It extends eastward
into portions of Kansas, Nebraska, Iowa, and Missouri [23,45].
ECOSYSTEMS :
FRES17 Elm - ash - cottonwood
FRES21 Ponderosa pine
FRES29 Sagebrush
FRES31 Shinnery
FRES34 Chaparral - mountain shrub
FRES35 Pinyon - juniper
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
STATES :
AZ CO IA KS MO MT NE NM ND OK
SD TX WY
ADMINISTRATIVE UNITS :
BADL BICA BUFF DETO FLFO GRSA
ROMO SCBL THRO WICA
BLM PHYSIOGRAPHIC REGIONS :
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
KUCHLER PLANT ASSOCIATIONS :
K011 Western ponderosa forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine - Douglas-fir forest
K023 Juniper - pinyon woodland
K037 Mountain mahogany - oak scrub
K038 Great Basin sagebrush
K053 Grama - galleta steppe
K054 Grama - tobosa prairie
K055 Sagebrush steppe
K056 Wheatgrass - needlegrass shrubsteppe
K059 Trans-Pecos shrub savanna
K064 Grama - needlegrass - wheatgrass
K065 Grama - buffalograss
K066 Wheatgrass - needlegrass
K067 Wheatgrass - bluestem - needlegrass
K070 Sandsage - bluestem prairie
K071 Shinnery
K098 Northern floodplain forest
SAF COVER TYPES :
237 Interior ponderosa pine
239 Pinyon - juniper
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
HABITAT TYPES AND PLANT COMMUNITIES :
Soapweed yucca is a common constituent of many plains grassland, drier
forest-grassland and prairie communities. It has been described as a
climax dominant on sandy range sites, and grasslands of Montana east of
the Continental Divide [35]. It is listed as an indicator in the
following range site classification scheme:
Climax vegetation of Montana based on soils and climate [35]
Associated plants: Soapweed yucca is commonly associated with the
following species in plains grassland communities: needle-and-thread
(Stipa comata), western wheatgrass (Pascopyrum (Agropyron) smithii),
blue grama (Bouteloua gracilis), sand bluestem (Andropogon gerardii var.
paucipilus), big bluestem (Andropogon gerardi var. gerardii), sideoats
grama (B. curtipendula), little bluestem (Schizachyrium scoparium),
sand dropseed (Sporobolus cryptandrus), galleta (Hilaria jamesii),
mesquite (Prosopis glandulosa), sunflower (Helianthus spp.), and
leadplant (Amorpha canescens) [3,10].
VALUE AND USE
SPECIES: Yucca glauca | Soapweed Yucca
WOOD PRODUCTS VALUE :
NO-ENTRY
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
Soapweed yucca provides food and cover for a number of species
throughout its wide range. Wild ungulates such as deer, bighorn sheep,
and bison utilize this species to at least some degree. Generally, use
by deer is fairly light, although Dusek [16] reported that soapweed yucca
represented up to 20% of winter mule deer diets in portions of
north-central Montana. Mule deer in this area also consumed smaller
amounts of soapweed yucca during the spring and summer [16]. It has been
used, generally in trace amounts, by bison on many shortgrass plains
sites [31]. Research indicates that soapweed yucca is of greatest
importance to bighorn sheep during late winter and early spring [40].
It is believed to represent an important and highly nutritious food
source for bighorns during times of climatic stress.
Cattle use of soapweed yucca appears to be fairly limited under normal
conditions [18]. However, during drought periods in the Great Plains,
cattle frequently consume flowers and succulent young leaves wherever
available [13]. Soapweed yucca was chopped and fed as emergency silage
to cattle during severe droughts in the early part of the century
[13,45]. Little documentation exists on the specific value of soapweed
yucca to domestic sheep and goats, although the leaves of many yuccas
are readily eaten by goats [45]. The fruits and flowers of most yuccas
are utilized by many small birds and mammals.
PALATABILITY :
Soapweed yucca appears to be relatively unpalatable to wild ungulates in
most areas. Leaves become tough, and spiny as they mature. Younger,
more succulent leaves, are much more palatable. However, during
droughts, when other more palatable species are lacking, soapweed yucca
may represent preferred forage. Soapweed yucca can be made palatable to
domestic livestock, for use during drought emergencies, by burning off
the older leaves and chopping the remainder of the plant for use as
silage to be added to supplements such as cottonseed meal [45]. Flowers
of soapweed yucca appear to be highly palatable to cattle [13], and
presumably to most wild ungulates as well. The fruits of most yuccas
are also palatable to a wide variety of birds and mammals. The relish
and degree of use shown by livestock and wildlife species for soapweed
yucca is rated as follows [14]:
CO MT ND WY
Cattle fair fair fair fair
Sheep poor fair poor fair
Horses fair fair fair fair
Pronghorn ---- poor ---- fair
Bighorn ---- ---- ---- ----
Elk ---- poor ---- fair
Mt. goat ---- ---- ---- ----
Mule deer ---- good fair ----
White-tailed deer ---- ---- ---- good
Small mammals ---- poor ---- poor
Small nongame birds ---- poor ---- poor
Upland game birds ---- poor ---- poor
Waterfowl ---- ---- ---- ----
NUTRITIONAL VALUE :
Soapweed yucca is rated as "poor" in overall energy and protein value
[14]. The nutritional value of soapweed yucca varies seasonally as
follows [6,20]:
% composition
Date moisture carotene ash crude crude crude
fat protein fiber
Jan.18 60.10 27.60 1.59 1.13 4.78 14.81
May 16 55.68 22.10 1.57 1.28 3.79 15.97
June27 64.71 18.04 1.87 .73 3.93 14.62
Oct 22 61.42 43.48 1.49 1.24 3.56 14.67
N-free extract Ca P Fe Mn
Jan.18 17.59 .33 .100 40.76 23.20
May 16 21.53 .43 .070 67.31 16.54
June27 14.14 .31 .117 32.82 7.84
Oct 22 17.62 .28 .077 47.11 13.34
average %
crude fiber ash protein
leaf 42.3 4.86 5.57
COVER VALUE :
Soapweed yucca provides good cover for a number of smaller birds and
mammals. Studies indicate that soapweed yucca serves as good hiding
cover for sharp-tailed grouse broods in North Dakota grasslands [22].
Scaled quail in southeastern New Mexico often incorporate soapweed yucca
leaves in their nests which are frequently situated at the base of the
plant [12]. Soapweed yucca provides the following environmental
protection during one or more seasons for wildlife species in a number
of western states [14]:
CO MT ND WY
Pronghorn ---- poor ---- fair
Bighorn ---- ---- ---- ----
Elk ---- ---- ---- poor
Mt. goat ---- ---- ---- ----
Mule deer ---- poor fair poor
White-tailed deer ---- ---- ---- poor
Small mammals ---- fair ---- poor
Small nongame birds ---- fair ---- poor
Upland game birds ---- poor ---- poor
Waterfowl ---- ---- ---- poor
VALUE FOR REHABILITATION OF DISTURBED SITES :
Soapweed yucca is rated as having low value for short-term
rehabilitation, and low to moderate value for use in long-term
rehabilitation [14]. Plants may be transplanted or grown from seed.
However, seedlings should be mulched in areas subject to winter frost
[1]. Researchers note that soapweed yucca can be somewhat difficult to
propagate [45].
OTHER USES AND VALUES :
Many Native Americans historically used soapweed yucca for a variety of
purposes. The saponin-rich roots were pulped to produce soap, thus
giving this species its common name [47]. Fibers obtained from the
leaves were fashioned into baskets, sandals, mats, and ropes [29].
During the early part of this century, soapweed yucca fiber was tested
as a jute substitute in burlap products or cordage. High tensile
strength (44.7 km), and clean, lustrous appearance made it well-suited
for these uses [5,6]. During World War I, soapweed yucca was used to
produce approximately 80 million pounds of fiber for bags and burlap
[6]. This species was also used to make paper for the United States
Navy during World War II [6,45].
Soapweed yucca is frequently planted as an ornamental [1].
MANAGEMENT CONSIDERATIONS :
Chemical control: Soapweed yucca is resistant to the effects of
herbicides. It is most susceptible during the bud stage, but only poor
to fair control has been achieved [48].
Mechanical removal: A number of experiments have focused on mechanical
removal or control of soapweed yucca. Researchers found that recovery
in the number of leafheads is generally not achieved until the third
year after treatment, although in some cases, recovery can occur within
3 months to 1 year. Recovery in the size (weight) of leafheads is
generally much slower and requires 5 1/2 to 6 3/4 years [45].
Occasionally 2 or 3 new plants grow from each original plant [6].
Evidence suggests that season of treatment and weather conditions do not
significantly influence the recovery of soapweed yucca although recovery
may be slightly slower if plants are damaged late in the year. Some
plants which had been cut at the soil surface produced inflorescences
within only 23 to 36 months. Even successive removal or damage has
failed to kill soapweed yucca. This resilient plant has continued to
sprout for 3 years or more after deep seasonal plowing [45].
Productivity: Webber [45] reported average soapweed yucca yields of 0.2
to 0.8 ton per acre. Soapweed yucca is known to decrease in response to
cattle grazing in parts of the Great Plains.
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Yucca glauca | Soapweed Yucca
GENERAL BOTANICAL CHARACTERISTICS :
Soapweed yucca is a small, acaulescent, perennial shrub which grows from
1 to 6 feet (.3-1.8 m) in height [1,45]. Plants are simple, or grow in
dense clumps 2.6 to 8.2 feet (0.8-2.5 m) in diameter, with short often
prostrate stems [23,45]. Soapweed yucca is typically deep-rooted [3],
and long-lived. Researchers estimated that a plant 5 feet (1.5 m) in
height was more than 50 years old [25].
The glaucous green leaves 1 to 3 feet (.3-1 m) in length are broad,
stiff, and sharply pointed with fibrous margins [21,23,48]. The
inflorescence is either racemose or paniculate, and up to .3 feet (1 m)
in length on a 1 to 4 feet (.3-1.2 m) tall flowerstalk [23,47]. The
flowers themselves are large, globose or campanulate and greenish-white
with a purple tinge [21,45]. The oblong fruit develops into a woody
capsule which contains numerous flat black, winged seeds [23,45,47].
RAUNKIAER LIFE FORM :
Phanerophyte
Geophyte
REGENERATION PROCESSES :
Soapweed yucca is capable of reproducing sexually or through vegetative
means. Typically, rosettes grow for several years, bloom once and die,
but are replaced by new rosettes derived vegetatively [28]. Winged seed
is shiny, black, and averages .006 ounce (16 mg) in weight [2,23,27].
Seed is contained in a dehiscent, woody capsular fruit 2 to 3 inches
(5-7 cm) long [23,26]. Plants generally first flower at 5 or 6 years of
age [45].
Germination: Soapweed yucca seed may lack a mechanism for dormancy
[28], and generally germinates well under favorable temperature and
moisture conditions [27,41]. Germination rates range from 45 to 98% but
generally average 80 to 90% under laboratory conditions [1]. However,
Arnott [1] observed that only 20% of the seed actually produced viable
seedlings in greenhouse experiments. Various treatments can influence
germination. Without pretreatment, germination generally begins within
1 or 2 weeks [1]. Seed soaked in water for 24 hours often germinates
within only 4 days [45]. Tolstead [41] reported that germination of
untreated seeds averaged 67.1% while seed vernalized for 2 months
averaged 86.6%. Germination may be adversely affected by exposure to
heat as shown below [27]:
% germination
exposure time control 80 C 90 C 100 C 110 C 120 C
2 hours 79 57 42 -- -- --
5 minutes -- -- 41 59 28 3
Pollination: One of the most interesting and well-studied aspects of
yucca ecology centers around the symbiotic relationship between yuccas
and their yucca moth pollinators. Soapweed yucca relies solely on the
yucca moth (Tegeticula yuccasella) for pollination [36]. Seed
production is thus totally dependent on the availability of this
pollinator which, in the larval stage, feeds on a small percentage of
seeds (generally around 7%) [26]. In some years, less than 1% of the
racemes set fruit due to lack of pollinators, or poor weather conditions
[28].
Vegetative regeneration: Evidence suggests that on newly disturbed
sites, which lack competing grasses, soapweed yucca regenerates
primarily from seed. Vegetative regeneration allow soapweed yucca to
survive and expand on sites with significant competition such as prairie
grasslands. On these sites a low ratio of seedlings to ramets is common
[28]. Vegetative regeneration occurs through the sprouting of
underground horizontal or oblique rhizomes which form a tangled network
approximately 4-24 inches (10-60 cm) below the soil surface. Rhizomes
are covered with a thick, rough, protective bark, branch and spread
horizontally with vertical branches growing to the soil surface where
new leafheads are formed. The connection to the mother plant gradually
becomes less important with time and eventually dies [45]. Ramets are
produced in late summer from lateral buds at the base of the
inflorescence or from rhizomes near senescent rosettes. The basal
diameter of individual rosettes is a good predictor of potential for
vegetative regeneration, with larger rosettes exhibiting a much greater
tendency to form new plants [28]. Soapweed yucca can resprout
relatively quickly even after successive defoliations. There is little
evidence to link season of injury or climatic factors with recovery
[45].
SITE CHARACTERISTICS :
Soapweed yucca grows on dry rocky outcrops, ridges, slopes, lower
mountains, prairies, and plains [23,38,44,47]. It is often found thinly
scattered in rolling grasslands or in open coniferous woodlands but also
occurs in dense stands in some areas [21,45].
Soils: This yucca grows well on a variety of soils including coarse
gravel, sand or porous loam [10,44]. Growth is ofen best on compact
sands and soapweed yucca is frequently described as an indicator of sand
[10].
Elevation: Generalized elevational ranges by state are as follows [14]:
from: 4,000 to 9,500 ft (1,219-2,896 m) in CO
2,500 to 5,000 ft (762-1,524 m) in MT
3,800 to 6,400 ft (1,158-1,951 m) in WY
SUCCESSIONAL STATUS :
Soapweed yucca can occur as a colonizer on disturbed sites [28], or as a
common climax dominant in a variety of plains grasslands, drier forest
communities and prairies [34,35]. Seedlings often thrive on disturbed
sites in which soil is exposed such as road cuts, overgrazed sites, or
slide zones. However, small seedlings often compete poorly with grasses
or older conspecifics. Existing plants or clones of this versatile
plant can still increase in area through vegetative regeneration in
grasslands or prairies. Interestingly, this yucca is described as both
an increaser in response to grazing, and a climax species. Geographic
variation in its reproductive modes and successional status is possible
[28].
SEASONAL DEVELOPMENT :
Soapweed yucca, unlike many of its plant associates, remains green
throughout the winter months [16]. Lateral buds located at the base of
the inflorescence produce new ramets during the late summer [28].
Flowering in this yucca typically occurs after a rosette has grown
vegetatively for a number of years. The individual rosette dies after
flowering but is replaced by new rosettes [28]. Generalized flowering
dates are as follows [14]:
location beginning of flowering end of flowering
CO May July
MT June July
ND June July
WY June July
Fruit of soapweed yucca ripens during July and August, and seed is
dispersed in September [1].
FIRE ECOLOGY
SPECIES: Yucca glauca | Soapweed Yucca
FIRE ECOLOGY OR ADAPTATIONS :
Soapweed yucca is described as "extremely difficult to kill with fire"
[38]. This species produces underground rhizomes which are presumably
well-protected from the effects of heat by overlying soil and a thick,
protective bark-like covering [45]. Seed germinates well [1] and
seedlings establish readily on newly disturbed areas with little
vegetation, such as recently burned sites.
Certain extremely harsh, rocky sites may lack fuels necessary to sustain
fire under ordinary circumstances.
POSTFIRE REGENERATION STRATEGY :
Rhizomatous shrub, rhizome in soil
Initial-offsite colonizer (off-site, initial community)
FIRE EFFECTS
SPECIES: Yucca glauca | Soapweed Yucca
IMMEDIATE FIRE EFFECT ON PLANT :
Precise effects may vary with season of burn, fire intensity and
severity, and site characteristics. Postfire mortality of soapweed
yucca has been reported [7,32,45]. However, many observers have noted
that soapweed yucca is extremely difficult to kill with fire [38].
Morphologically similar species frequently survive and resprout even
when all aboveground vegetation is consumed by fire. Soapweed yucca is
rarely killed by other types of disturbance such as mechanical removal
[45].
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
NO-ENTRY
PLANT RESPONSE TO FIRE :
This species is generally capable of regenerating through sprouting of
underground rhizomes, located 4 to 24 inches (10-60 cm) beneath the
surface [45], which are presumably somewhat protected from heat damage by
overlying soil. Morphologically similar yuccas resprout prolifically
after fire, and although vigorous sprouting has been observed following
mechanical removal of soapweed yucca, a similar postfire response has
not been widely reported in the literature. However, soapweed yucca has
been observed to decrease in response to burning [7,32]. The protective
bark which covers the rhizomes tends to thicken as plants age, and
limited evidence suggests that older, larger plants are more likely to
regenerate vegetatively [28]. Therefore, it is probable that older
plants are more likely to sprout after fire. Additional research is
needed to clarify the importance of such factors as fire intensity and
severity, climate, soils, season of burn, and grazing history. Ecotypic
or geographic variation is also possible.
Recovery of soapweed yucca on d a site may be relatively rapid even
where reestablishment occurs primarily through seed. Seeds germinate
rapidly [1], and seedlings reportedly establish readily on newly
disturbed sites which lack grasses or other competitors [28]. Maturation
is rapid and flowering has been reported in plants as young as 5 or 6
years of age [45].
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS :
The tender young shoots of soapweed yucca are highly palatable to
livestock, particularly in drier years, and to rodents such as woodrats
[13,45]. Postfire recovery may be poor where rodent numbers are unusually
high [45]. In some areas, grazing must be limited to ensure good
postfire recovery.
REFERENCES
SPECIES: Yucca glauca | Soapweed Yucca
REFERENCES :
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Index
Related categories for Species: Yucca glauca
| Soapweed Yucca
|
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