Index of Species Information
SPECIES: Hesperoyucca whipplei
SPECIES: Hesperoyucca whipplei
AUTHORSHIP AND CITATION :
Tirmenstein, D. A. 1989. Hesperoyucca whipplei. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
Hesperoyucca whipplei (Torr.) Baker 
Yucca newberryi McKelvey
Yucca whipplei Torr. [46,51,52]
Yucca whipplei subsp. caespitosa M.E. Jones [17,31,51,52]
Yucca whipplei subsp. eremica Haines and Epling [18,45]
Yucca whipplei subsp. intermedia A.L. Haines [17,31]
Yucca whipplei subsp. newberryi (McKelvey) Webber [18,45]
Yucca whipplei subsp. parishii M.E. Jones [17,31]
Yucca whipplei subsp. peninsularis (McKelvey) Webber [18,45]
Yucca whipplei subsp. percursa A.L. Haines [17,31]
Yucca whipplei subsp. whipplei [17,31,51,52]
SCS PLANT CODE :
COMMON NAMES :
Our Lord's candle
The currently accepted scientific name of chaparral yucca is Hesperoyucca
whipplei (Torr.) Trel. (Agavaceae) [49,52]. Natural hybridization is
common in chaparral yucca and other Yucca species, and numerous
intermediate forms occur . The yuccas have received only limited
attention from past researchers, and many taxonomic questions remain
. In many areas, hybridization and gene flow occur freely across
chaparral yucca populations, while in other areas, populations are isolated
by geographic barriers . As a result, this species exhibits much
variation in growth habit, general ecology, reproductive strategies, phenology,
and gross morphology.
LIFE FORM :
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
DISTRIBUTION AND OCCURRENCE
SPECIES: Hesperoyucca whipplei
GENERAL DISTRIBUTION :
Chaparral yucca occurs from coastal southern California across
portions of the Mohave Desert southward into Mexico [24,40,41,45].
FRES21 Ponderosa pine
FRES30 Desert shrub
FRES34 Chaparral - mountain shrub
FRES35 Pinyon - juniper
BLM PHYSIOGRAPHIC REGIONS :
3 Southern Pacific Border
7 Lower Basin and Range
KUCHLER PLANT ASSOCIATIONS :
K005 Mixed conifer forest
K023 Juniper - pinyon woodland
K035 Coastal sagebrush
K045 Ceniza shrub
SAF COVER TYPES :
239 Pinyon - juniper
241 Western live oak
245 Pacific ponderosa pine
255 California coast live oak
SRM (RANGELAND) COVER TYPES :
HABITAT TYPES AND PLANT COMMUNITIES :
Chaparral yucca in Tulare County chaparral.
Photo by Mark W. Skinner @ USDA-NRCS
Chaparral yucca is listed as a dominant in a number of coastal sage
scrub and chaparral communities of southern California. Common
codominants include California broomsage (Lepidospartum squamatum),
thickleaf yerba-santa (Eriodictyon crassifolium), and California
sagebrush (Artemisia californica) .
SPECIES: Hesperoyucca whipplei
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
The flowers and fruits of chaparral yucca are used by a number of
small birds and mammals [2,9]. This species provides little browse for
domestic livestock or wild ungulates , although some use of the
flowers has been reported . It presumably provides some cover for
smaller birds and mammals.
Fruits of chaparral yucca are highly palatable to many species of
birds, the dusky-footed woodrat, and numerous other small mammals [2,9].
Flowers and flowerstalks are apparently favored by mule deer in some
NUTRITIONAL VALUE :
Little specific information is available on the food value of Our Lord's
candle. Nutritional values for the genus Yucca are as follows [7,32]:
water ash crude crude fat n-free ether protein
protein fiber extract extr. n x6.25
young stem, dry -- 5.55 7.50 16.13 1.54 69.28 -- --
old stems -- 9.15 3.07 19.59 0.93 67.26 -- --
fresh stems 72.1 1.55 2.09 4.50 0.43 19.33 -- --
fresh flowers -- 8.7 -- 13.3 -- 53.3 4.4 20.3
COVER VALUE :
VALUE FOR REHABILITATION OF DISTURBED SITES :
Little documentation exists on the potential value of chaparral yucca
for rehabilitation. Studies indicate that seedlings can be successfully
transplanted . However, Webber  emphasizes the importance of
not overwatering young plants, and notes that propagation of this
species is sometimes difficult.
OTHER USES AND VALUES :
Native Americans made flour from the seeds and used fibers from the
leaves to weave rope, nets, and baskets. They roasted the very young
flowerstalks to produce a food that tasted like baked apple. The roots
have a high component of saponin; when soaked and pounded they produce
copious suds . The flowers of chaparral yucca are sometimes made
into various novelty products .
OTHER MANAGEMENT CONSIDERATIONS :
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Hesperoyucca whipplei
GENERAL BOTANICAL CHARACTERISTICS :
Chaparral yucca is a highly variable, rosette-forming, perennial shrub
[23,45]. Plants are distinguished by growth form (caespitose or
solitary) and color, size, and shape of leaves and flowers [10,13,17].
Chaparral yucca may also differ in phenological development, fruit set,
and growth habit. Varying forms occur in most populations .
RAUNKIAER LIFE FORM :
REGENERATION PROCESSES :
Chaparral yucca reproduces both by seed and by sprouting .
Many populations have mixtures of monocarpic, caespitose, and
rhizomatous growth forms .
Flowering and fruiting: Attractive, creamy-white or sometimes
purplish-tinged flowers are borne on flowerstalks which generally grow 8
to 21 feet (2.5-3 m) in height
. The inflorescence is a pedant panicle made up of one hundred to
several thousand flowers . Size of the showy inflorescence is varible;
it may average 3 feet in length and 13 inches in diameter, or sometimes,
be twice that large (averaging 6.5 feet in length and 2 feet in diameter).
The lower portion of the panicle develops fruit while the upper part is
still flowering . Each dehiscent fruit contains approximately 150 to
200 flat, smooth, dull black seeds, which are dispersed by wind [40,45].
Germination: Germination rates are variable , ranging from 0 to 100
percent in controlled laboratory experiments . When viability is high,
germination may be rapid. Germination of seed presoaked in water for 24
hours began within 3 days of treatment . Despite the occurrence of
chaparral yucca in fire-prone chaparral, seed is vulnerable to high
temperatures. Significant reductions in germination have been noted
after even brief exposure to high temperatures .
Pollination: One of the most interesting and well-studied aspects of
yucca ecology centers on the symbiotic relationship between yuccas and
their yucca-moth pollinators. Chaparral yucca relies solely on the
yucca moth (Tegeticula maculata), which consumes a small percentage of
flowers while in the larval stage, for pollination . Seed production
is limited not only by the resources available to the parent plant, but
by pollinator numbers as well [2,14,41]. Many of the regenerative
strategies used by Chaparral yucca reflect competition for potentially
scarce pollinators .
Vegetative: Chaparral yucca regenerates vegetatively by producing
multiple, densely packed rosettes from axillary buds early in
development; these rosettes are attached to a small caudex . This
mode of regeneration allows it to persist or increase even
on harsh sites. Some populations rarely, if ever, forms rhizomes
[23,45]. Some plants regenerate vegetatively via axillary
branching, which occurs only after plants are mature; the base of the
stem and roots persist after flowering to form the subterranean portion
of the new plants [13,17]. Some plants or populations reproduce vegetatively
through thick, underground rhizomes [13,21,23]. Rhizomes average 2 to 6
feet (0.6-1.8 m) in length, and sprouting often results in the formation
of dense clone [17,23].
SITE CHARACTERISTICS :
Chaparral yucca grows from 980 to 8,200 feet (300-2,500 m) elevation .
Topography includes dry, stony slopes on foothills, coastal plains [2,31],
bare, rocky, mountain slopes or mesas [21,23,45], and desert fringes of
southern California and Mexico [2,31]. It grows particularly well on mountain
slopes and alluvial fans .
Soils: Chaparral yucca grows well on a variety of soil types including
unconsolidated or granitic substrates . Growth is most common on
very porous, shallow soils or on rocky outcrops .
It is a common understory species in maritime , coastal sage shrub,
chaparral [17,31], California juniper (Juniperus californica) woodlands,
and in desert shrub [17,31,45], and into ponderosa pine (Pinus ponderosa)
Plant associates: Coastal sage - sage (Salvia spp.), lemonade sumac
(Rhus integrifolia), California scrub oak (Quercus dumosa), chokecherry
(Prunus spp.), mountain-mahogany (Cercocarpus betuloides), California
broomsage (Lepidospartum squamatum), and thickleaf yerba-santa
(Eriodictyon crassifolium) [24,40]. Desert scrub - creosotebush (Larrea
tridentata). Chaparral - oaks (Quercus spp.), ceanothus (Ceanothus
spp.), manzanita (Arctostaphylos spp.), chamise (Adenostoma
fasciculatum), and red shank (A. sparsifolium) .
SUCCESSIONAL STATUS :
The successional role of chaparral yucca has not been well documented.
It probably occurs as a climax species on some fairly harsh sites, and
is well adapted to persist in fire-prone chaparral communities.
SEASONAL DEVELOPMENT :
Our Lords's candle generally flowers from late February to early June
[1,10]. Only some plants in a particular area flower in any given year,
while the rest undergo vegetative growth. This annual variation in
reproductive effort may represent an adaptation for greater overall
reproductive success despite limited pollinator availability or aberrant
Flowering: Individual plants flower for 2 to 7 weeks , but the
population flowers for 2 or less commonly 3 months [5,41]. Flowering
tends to be influenced by factors such as rainfall, floral structure,
and elevation [5,10,42]. Flowering generally begins later at higher
elevations, and during extremely dry years, most stands have few if any
individuals which produce flowers . Chaparral yucca may only
bloom for 10 days on very dry sites, while plants on more mesic sites
flower for up to 30 days . Each flower on the inflorescence is only
open for a few days . Flowers at the bottom of the panicle begin
development much earlier than those above [14.]
Fruiting: Fruit development begins at the bottom of the panicle several
weeks after the first flowers have wilted but while the upper flowers
are still in bloom . Fruit set tends to be low, but is somewhat
higher in fruit at the bottom of the panicle . Fruits reach full
size within a month; seed pods mature, turning dry and gray-brown, by
late summer or fall . The first pods dehisce while the last flowers
are wilting . Wind dispersal usually begins by mid-August .
The monocarpic plants turn brown and die by late summer or fall in the
year of flowering . These plants generally complete their life cycle
within 4 to 7 years [10,28].
SPECIES: Hesperoyucca whipplei
FIRE ECOLOGY OR ADAPTATIONS :
The specific fire adaptations of chaparral yucca vary greatly
within and among populations. Even individuals within a given population may
exhibit varying adaptations to fire. Diverse regenerative strategies of
chaparral yucca may represent local adaptations to the fire
frequency most common in the habitat occupied by that population. Genetic
variation present within populations may have allowed chaparral yucca
to persist or spread despite climatic shifts leading to changes in fire
frequency or subsequent geographic isolation.
Chaparral yucca is generally well adapted to persist in fire-prone
environments, and is closely associated with chaparral types .
However, chaparral yucca often grows in openings within chaparral
communities where fuel levels are lower than those of surrounding
areas . This may result in lighter fires and increased survival.
On some extremely harsh, rocky sites occupied by the species, fire
may be infrequent due to insufficient fuels.
Large, densely packed leaf bases provide some protection from fire .
Fairly vigorous sprouting has been noted after many fires
[29,35,38,38], but in other instances, little if any sprouting has
occurred and high mortality has been observed . Plants frequently
survive and resume growth if only lightly damaged [9,19,48]. Specific
plant morphology may largely dictate the probability of survival and
most typical mode of postfire response. Conditions which favor
rhizomatous or caespitose forms of chaparral yucca are generally not
conducive to seedling germination and establishment .
Some popultaions exhibit a larger leaf area than most, which may allow
for more rapid growth rates in fire-free years, a characteristic of
selective value in fire-prone habitats . Also, although seed of
chaparral yucca is in general very sensitive to heat damage, seeds of
some popultaions are more resistant to exposure to high temperatures
(up to 230 degrees Fahrenheit [110 deg C]) than others .
Reestablishment is probably through surviving on-site or off-site
Rhizomes vary in depth, length, and thickness but are probably well
protected from fire by overlying soil. Plants can probably sprouting
rapidly after fire. Many of the populations of chaparral yucca sprout
vigorously and rapidly, even after fires of high intensity.
Plants with a caespitose growth form may show best survival in
areas experiencing lighter fires. Undamaged or slightly damaged
portions of the clump would survive and resume growth, permitting fairly
rapid reestablishment .
Some plants grow in a dense clump of rosettes with secondary rosettes
forming from underground portions of older plants [17,45]. These
underground plant parts are presumably protected from the damaging effects
of heat by overlying soil. These adaptations suggest that plants with
rosettes can survive and resume growth, particularly after light fires.
FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find Fire Regimes".
POSTFIRE REGENERATION STRATEGY :
Secondary colonizer - off-site seed
Rhizomatous shrub, rhizome in soil
SPECIES: Hesperoyucca whipplei
IMMEDIATE FIRE EFFECT ON PLANT :
The effect of fire on chaparral yucca probably varies according to
such factors as fire intensity and severity, climate, site
characteristics, and genetic makeup of a particular population.
Although major differences among populations have been documented
with respect to botanical characteristics and regenerative strategies,
little is known about these differences influence plant repsonses to
fire. The literature reports variable and seomtimes contradictory information on
effects and response of chaparral yucca to fire. Some researchers
have observed low postfire mortality of chaparral yucca (< 25%) [37,38],
while others have reported low survival (10%) [19,20]. Much of the
variability in fire effects is probably due to genetically based
differences in growth habit and regeneration strategies.
Postfire mortality is probably high in semelparous, monocarpic
plants. A fire which consumes aboveground vegetation would presumably
kill the plant, although some individuals might survive if the foliage
was only lightly damaged.
Survival is probably more likely in plants that are not monocarpic,
since they have the ability to survive and regrow if portions of the
dense clump or clone remain undamaged. Some plants or populations form
new secondary rosettes from underground portions of older plants; fires
which occur after the formation of these buds but prior to emergence
may have little effect on the buds themselves.
Postfire mortality is presumably low in rhizomatrous plants because the
rhizomes are afforded some protection from heat by overlying soil,
allowing the plant to survive even when aboveground vegetation is
consumed by fire.
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
PLANT RESPONSE TO FIRE :
Postfire response of chaparral yucca is extremely variable. This diverse
species shows extreme variability, and many growth forms can be observed in a
single population. More research is needed to sort out the complex
interrelationships between genetic and environmental factors which influence
postfire regenerative strategies of chaparral yucca.
Postfire response of chaparral yucca may be rapid. Sprouts or
seedlings appeared within 2 years after a September fire removed all
aboveground vegetation . Sprouting, when it occurs, can be vigorous.
As many as 262 to 1,690 sprouts per hectare were observed only 1 year
after a July wildfire in a chaparral-desert ecotone of southern
California [37,38]. On certain sites which had a prefire density of 27
per hectare, sprout densities were averaged 20 per hectare. Each
plant produced an average of 18 to 85 sprouts [37,38], suggesting
increased density in burned stands. Basal sprouting appears to be most
likely when foliage is not "severely burned" . Limited evidence
suggests that where chaparral yucca is capable of sprouting, this
mode of regeneration allows for much more rapid and complete recovery
than would be expected in populations which regenerate through seed
alone . In many instances, chaparral yucca appears to be capable
of surviving and resuming growth if only slightly damaged by fire
[9,19,48]. Some lightly burned stands produce an abundance of flowers
within 1 or 2 years after fire .
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
Recovery: Vegetative regeneration of chaparral yucca through
sprouting apparently permits a much more rapid and vigorous postfire
recovery than is possible through seedling establishment. Specific
documentation of recovery following a fall fire of variable intensity in
a coastal sage scrub community is as follows :
site # % cover (#/ha) mean size (cm sq)
sprout seedling sprout seedling
1 4.3 -- 2,344 156
3 12.1 0.1 1,875 156
4 8.8 0 1,562 469
5 4.3 -- 937 --
6 10.8 0 1,719 156
Postfire recovery of chaparral yucca cover through seed alone may take
more than 4 years in many southern California chaparral communities
Although evidence is lacking, the likelihood of vegetative regeneration
in individuals or populations capable of such a response may depend
largely on fire severity. Conrad  reports that basal sprouting can
occur only if plants are not severely burned.
FIRE MANAGEMENT CONSIDERATIONS :
One year after a summer wildfire in a California chaparral-desert shrub
ecotones, postfire productivity ranged from 0.05 pounds per acre (57
g/hectare) in winter to 11 pounds per acre (1,196 g/hectare) in spring
SPECIES: Hesperoyucca whipplei
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