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Wildlife, Animals, and Plants
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Introductory
SPECIES: Yucca schidigera | Mojave Yucca
ABBREVIATION :
YUCSCH
SYNONYMS :
Yucca mohavensis Sarg.
SCS PLANT CODE :
YUSC2
COMMON NAMES :
Mojave yucca
TAXONOMY :
The currently accepted scientific name of Mojave yucca is Yucca
schidigera Roezl. ex Ortgies. [9,40].
Mojave yucca is known to hybrizide with Y. baccata and Y. constricta
[37,38].
LIFE FORM :
Tree, Shrub
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
COMPILED BY AND DATE :
D. Tirmenstein, March 1989
LAST REVISED BY AND DATE :
D. Tirmenstein, August 1990
AUTHORSHIP AND CITATION :
Tirmenstein, Debra A. 1990. Yucca schidigera. In: Remainder of Citation
DISTRIBUTION AND OCCURRENCE
SPECIES: Yucca schidigera | Mojave Yucca
GENERAL DISTRIBUTION :
Mojave yucca occurs from coastal southern California and northern Mexico
eastward into northwestern Arizona and southern Nevada [18,39]. As its
name implies, this yucca is closely associated with Mojave Desert
vegetation through much of its range [18].
ECOSYSTEMS :
FRES30 Desert shrub
FRES34 Chaparral - mountain shrub
FRES35 Pinyon - juniper
FRES40 Desert grasslands
STATES :
AZ CA NV UT MEXICO
ADMINISTRATIVE UNITS :
CABR JOTR LAME
BLM PHYSIOGRAPHIC REGIONS :
3 Southern Pacific Border
7 Lower Basin and Range
12 Colorado Plateau
KUCHLER PLANT ASSOCIATIONS :
K033 Chaparral
K035 Coastal sagebrush
K041 Creosotebush
SAF COVER TYPES :
239 Pinyon - juniper
SRM (RANGELAND) COVER TYPES :
205 Coastal sage shrub
211 Creosotebush scrub
212 Blackbush
412 Juniper-pinyon woodland
504 Juniper-pinyon pine woodland
506 Creosotebush-bursage
508 Creosotebush-tarbush
HABITAT TYPES AND PLANT COMMUNITIES :
Mojave yucca is a common constituent of Joshua tree (Yucca brevifolia)
woodlands and desert shrub communities [29]. It extends into the lower
reaches of many pinyon-juniper (Pinus-Juniperus spp.) woodlands,
throughout desert shrub communities, and into coastal chaparral of
southern California [12,15,20,39].
Plant associates: Mojave yucca commonly grows with California sagebrush
(Artemisia californica), pricklypear (Opuntia spp.), Joshua tree, banana
yucca, blackbrush (Coleogyne ramosissima), creosotebush (Larrea
tridentata), white sage (Salvia apiana), California buckwheat (Eriogonum
fasiculatum), and sugar sumac (Rhus ovata) [12,29,40].
VALUE AND USE
SPECIES: Yucca schidigera | Mojave Yucca
WOOD PRODUCTS VALUE :
NO-ENTRY
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
Browse: Mojave yucca provides browse for a number of wildlife species
during spring, summer, and fall [30,31]. Although use is comparatively
light in many areas, a southern California study reported Mohave yucca
to be a preferred spring browse species [30. Use was particularly heavy
during spring and fall on burned sites [30,31]. Although levels of
utilization on these burn sites were somewhat variable, up to 14.8
percent of all Mojave yucca sprouts had been browsed [30].
Livestock rarely utilize Mojave yucca, although small amounts of
immature flowerstalks are occasionally eaten by cattle. Cattle on
severely overgrazed ranges also reportedly browse Mojave yucca [7].
Domestic goats utilize the leaves of many species of yucca [37] and
probably feed on Mohave yucca where available.
Fruit: Woodrats and ground squirrels, and presumably other small
mammals, birds, and livestock, consume the fruits and seeds of Mojave
yucca [8,36, R. Hunter, pers. comm. 1989].
PALATABILITY :
The flowerstalks and foliage of Mojave yucca are palatable to cottontail
rabbits, black-tailed jackrabbits, and some wild ungulates during much
of the year [30]. Palatability may be greatest in spring [30]. The
fruits are highly palatable to a number of small birds and mammals.
The foliage of Mojave yucca is relatively unpalatable to cattle [7], but
the flowerstalks are palatable to cattle until the fruit matures and the
stalks dry out.
NUTRITIONAL VALUE :
The nutritional content of Mojave yucca has been examined in detail
[6,36]. Selected nutrient values are as follows [6,36]:
Water Ash Crude Crude Fat N-free
(%) (%) Protein(%) Fiber(%) (%) Extract(%)
---------------------------------------------------------------
4.31 5.34 4.33 31.64 1.90 52.48
Zn Cu Fe Mn B Al Si Ba P Na K Ca Mg
(ppm) (% dry weight)
-------------------------------------- --------------------------
65 21 111 47 31 44 51 5.0 .28 .006 1.86 1.36 .45
COVER VALUE :
Mojave yucca provides shade and cover for many small birds and mammals.
Woodrats commonly build nests at the base of plants [36]. Snakes and
lizards also presumably hide or rest in close proximity to this plant.
VALUE FOR REHABILITATION OF DISTURBED SITES :
Mohave yucca grows in fragile desert environments that are vulnerable to
many types of disturbance [34]. Recovery of these unique arid
communities often requires many centuries. Evidence suggests that
slow-growing climax species such as the Mohave yucca are particularly
susceptible to deep soil disturbances and recover very slowly [33].
Mohave yucca can be propagated for use in rehabilitation through a
number of methods. Plants can be grown from seed, which is generally
planted in March or April [28], or sprouts can be cut close to the
parent plant with some roots attached and then planted [37]. Initial
growth on disturbed sites is very slow [R. Hunter, pers. comm. 1989].
Little documentation exists on the potential use of Mohave yucca in
rehabilitation.
OTHER USES AND VALUES :
Native Americans of the Southwest traditionally used Mojave yucca for
numerous purposes. Fruits were eaten raw or dried for later use.
Leaves, which contain high levels of saponin, a detergentlike substance,
were pulped to produce soap. Fibers obtained from the leaves were made
into rope, twine, hats, hair brushes, shoes, mattresses, and saddle
blankets [20].
Experiments conducted during the early part of this century indicated
that fibers derived from many yuccas could serve as a satisfactory
substitute for jute because of their relatively high tensile strength
(50.4 km) and lustrous white appearance [5]. Extracts made from
steroidal saponins of Mojave yucca are used to treat arthritis and as
antistress agents for humans and poultry [16]. Derivatives of these
useful compounds are used as plant fertilizer, as additives to promote
weight gain in cattle, and to lessen ammonia formation of poultry wastes
[10,16].
MANAGEMENT CONSIDERATIONS :
Productivity: Productivity of Mojave yucca varies greatly according to
site. In California chaparral communities, Tratz [30] reported
production ranging from 0.45 to 1.1 pounds (20-5-489 g) per plant, with
highest levels occurring on drier ridges. Average Mojave yucca biomass
has been estimated at 837 pounds per acre (927 kg/ha) [25] and up to
8,283 pounds per acre (9,300 kg/ha) in dense stands [36].
Mechanical removal: Efforts have been made to reduce or eliminate
Mojave yucca through mechanical means. Results of these experiments
suggest that the greater the injury, the less likely the recovery of
Mohave yucca [37]. Plants that had only sprouts and leafheads severed
produced many more sprouts than did plants that had the entire stem
removed [37]. Plants which were mechanically damaged in May produced 0
to 9 sprouts, 3 to 9 inches (8-23 cm) long by the following June [37].
Sprouts from the less severely damaged plants generally appeared to be
more vigorous.
Chemical control: Mojave yucca appears to be resistant to atrazine
herbicides [R. Hunter, pers. comm. 1989].
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Yucca schidigera | Mojave Yucca
GENERAL BOTANICAL CHARACTERISTICS :
Mojave yucca can be arborescent or shrublike, with single or clumped
erect stems [39]. This highly variable, long-lived, slow-growing
species is simple-stemmed or sparingly branched, with the first branches
occurring a few feet off the ground [20]. Mojave yucca generally grows
from 9.2 to 14.8 feet (2.8-4.5 m) tall, although specimens as tall as 30
feet (9 m) have been reported [20,21]. Individual plants may live for
hundreds of years [27]. The gray-brown bark is rough and ridged [20].
Linear to linear-lanceolate, yellow-green or blue-green leaves 1 to 4.9
feet (3-15 dm) in length occur in clusters at the end of branches
[20,22,40]. Dead leaves along the stems often extend nearly to the
ground [20]. The densely crowded, glabrous to slightly scabrous,
fragile inflorescence is 2 to 4 feet (0.65-1.30 m) long and pale
yellow-green with a red or purple tinge [20]. Small globose flowers are
white or cream-colored and often tinged with purple [20,37]. The plump,
fleshy fruit is tapered and cylindrical and contains numerous thick,
dull black, wingless, ovoid seeds [20,22,37].
RAUNKIAER LIFE FORM :
Phanerophyte
Geophyte
REGENERATION PROCESSES :
Seed: Seed is flat, dull black and weighs approximately 0.005 ounce
(139 mg) [2,15,37]. The seed is contained in large, plump, indehiscent,
baccate fruits which frequently remain on the tree until early winter
[14,20]. These sweet, fleshy fruits are eaten by many vertebrates,
which are the primary dispersal agents [40]. Plants may not produce
fruit in poor years [36].
Pollination: One of the most interesting and well-studied aspects of
yucca ecology is the symbiotic relationship between yuccas and their
yucca moth pollinators. Mojave yucca relies solely on the yucca moth
(Tegeticula yuccasella) for pollination [41,42,43]. Seed production is
thus entirely dependent on the availability of this pollinator, which
while in the larval stage, feeds on a small number of seeds (generally
around 3 percent) [14]. In years of extremely low pollinator
availability, sexual reproduction may not occur.
Germination: The seeds of most yuccas germinate well when planted under
favorable temperature and moisture regimes [15]. Seed viability
approaches 80 percent [2]. Germination can occur within only 6 days if
seed is first soaked in water for 24 hours [37]. Germination capacity
is reduced when seeds are subjected to high temperatures for even brief
periods of time [15]. Percent germination of seed exposed to different
temperatures for varying lengths of time was as follows [15]:
Percent Germination
2 hours 5 minutes
------------- ------------------------------
Control 80 C 90 C 90 C 100 C 110 C 120 C
--------------------------------------------------------------
69 16 0 83 54 11 0
Vegetative regeneration: Very few seedlings have been observed on many
of the harsh sites on which Mojave yucca grows [40]. Reproduction by
seed may have been much more important during more favorable climatic
regimes. Most regeneration now probably occurs through root-sprouting,
which has been noted after fire or mechanical removal [7,30].
SITE CHARACTERISTICS :
Mojave yucca grows on dry rocky slopes, mesas, sandy desert washes, and
bajadas [22,29]. Dense concentrations of this species are rare in
southern California but do occur in Arizona and Nevada [37].
Soils and climate: Mojave yucca generally occurs on gravelly soils
[37], and has been reported on alkaline and saline soils [28,36]. It is
well adapted to xeric conditions and can grow in areas receiving only 6
inches (150 mm) of precipitation annually [28]. Coastal sage sites of
southern California in which this yucca grows are characterized by
winter rains but very little summer precipitation [3].
Elevation: Generalized elevational ranges of Mojave yucca are as
follows [20,21,39,36]:
from less than 5,000 feet to (rarely) 7,800 feet (1,524-2,377 m) in CA
from 2,198 to 2,952 feet (670-900 m) in se NV
from 2,952 to 3,650 feet (900-1,100 m) in s NV
from 2,952 to 4,920 feet (900-1,500 m) in UT
SUCCESSIONAL STATUS :
Mojave yucca is a slow-growing and long-lived species [37]. It is a
constituent of certain climax desert shrub communities [33]. This yucca
is susceptible to deep-soil disturbance and reestablishes a site slowly
and gradually [33]. It is generally not well represented in early seral
communities.
SEASONAL DEVELOPMENT :
Mojave yucca flowers during the early spring [1]. Fruit develops in
late spring to early summer [1] and sometimes remains on the plant into
early winter [20].
Evidence suggests that the timing of flowering is primarily controlled
by daylength [1]. Temperature is also an important influence, and
flowering is often delayed at higher elevation sites [20]. Generalized
flowering and fruiting dates are as follows [1,20,22,28]:
Location Beginning of flowering End of flowering Fruiting
CA April May April
NV March May May
Significant annual variation in seasonal development has been noted;
climatic factors may account for this variation. Specific phenological
development at a Nevada site over a 3-year period was as follows [1]:
Phenological stage 1971 1972 1973
Bud March ---- April
Flower March March April
Fruit May-July April-July May-June
FIRE ECOLOGY
SPECIES: Yucca schidigera | Mojave Yucca
FIRE ECOLOGY OR ADAPTATIONS :
Mojave yucca is well adapted to survive most fires. It can sprout from
roots protected by overlying soil, or from surviving active tissues at
the stem base [7,30,37]. Certain dry, rocky sites occupied by Mohave
yucca may lack sufficient fuels to carry a fire under ordinary
circumstances.
POSTFIRE REGENERATION STRATEGY :
Tall shrub, adventitious-bud root crown
Geophyte, growing points deep in soil
FIRE EFFECTS
SPECIES: Yucca schidigera | Mojave Yucca
IMMEDIATE FIRE EFFECT ON PLANT :
Mojave yucca is generally not killed by fire even when aboveground
vegetation is totally consumed. Researchers in chaparral-desert
ecotones of southern California observed that less than 10 percent of
all Mojave yuccas were actually killed by fire [30,31]. In a desert
grassland, only a few plants were killed by a summer fire which removed
old shoots to or near the ground level [37].
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
NO-ENTRY
PLANT RESPONSE TO FIRE :
Mojave yucca generally sprouts from the roots or from nodules located on
the stembase after aboveground foliage is partially or totally consumed
by fire [7,35,37]. Because of this prolific sprouting ability, plants
often become multistemmed and stands more dense after fire [30,31].
Individual plants which had burned to ground level 1 year before formed
an average of one to four sprouts in desert grasslands of the Southwest
[37]. Plants produced even more sprouts in southern California
chaparral-desert shrub ecotones. An average of 5 to 153 sprouts per
plant were present by 1 year after fire, or 10 to 1,228 sprouts per acre
(25-3,034 per hectare). Sprout production was somewhat greater on
ridges than in canyons [30,31].
Sprouts tend to be small and growth is generally slow [37]. Researchers
estimate that in many desert grasslands, Mojave yucca requires 5 or 6
years to equal prefire cover, and many more years are necessary for
recovery in height and biomass [37]. On a southern California chaparral
site, however, leaves averaged more than 3 feet (1 m) in length only 2
years after fire, and at least 23 leaf clusters, representing a 2.5
increase in plant numbers, were present [30,31]. Recovery rates may
vary according to fire severity and intensity, season of burn, and
specific site characteristics.
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS :
The tender young sprouts of Mojave yucca are palatable to many rodents
and lagomorphs. Burned areas may fail to recover if large numbers of
small mammals are present [37].
REFERENCES
SPECIES: Yucca schidigera | Mojave Yucca
REFERENCES :
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mutualism: the interaction between yuccas and yucca moths. Oecologia.
70: 486-494. [8880]
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after fire. American Midland Naturalist. 77(1): 234-238. [11745]
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Index
Related categories for Species: Yucca schidigera
| Mojave Yucca
|
 |
