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Wildlife, Animals, and Plants
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Introductory
SPECIES: Yucca whipplei | Our Lord's Candle
ABBREVIATION :
YUCWHI
SYNONYMS :
Hesperoyucca whipplei (Torr.) Baker
Yucca newberryi McKelvey
SCS PLANT CODE :
YUWH
COMMON NAMES :
Our Lord's candle
chaparral yucca
quixote yucca
TAXONOMY :
The currently accepted scientific name of Our Lord's candle is Yucca
whipplei Torr. The Yucca genus is described as both variable and
unstable [46]. Natural hybridization is common, and numerous
intermediate forms occur [45]. The yuccas have received only limited
attention from past researchers, and many taxonomic questions remain
[11]. Our Lord's candle is a particularly difficult group. Earlier
researchers suggested placing this taxonomic entity in a separate genus,
Hesperoyucca, to accomodate its unique range of characters [5].
However, modern taxonomists have retained this group within the Yucca
genus as Yucca whipplei. In many areas, hybridization and gene flow
occur freely across populations, while in other areas, populations are
isolated by geographic barriers [18]. As a result, this species
exhibits much variation in growth habit, general ecology, reproductive
strategies, phenology, and gross morphology.
Modern taxonomists have identified five or more distinct subspecies
[5,17]; numerous ecotypes also occur [18]. Currently recognized
subspecies are as follows [17,31]:
Yucca whipplei ssp. caespitosa Jones
Yucca whipplei ssp. intermedia Haines
Yucca whipplei ssp. percursa Haines
Yucca whipplei ssp. parishii
Yucca whipplei ssp. whipplei
A number of researchers also recognize the following subspecies [18,45]:
Yucca whipplei ssp. peninsularis (McKelvey) Webber
Yucca whipplei ssp. eremica Haines and Epling
Yucca whipplei ssp. newberryi (McKelvey) Webber
However, several of these taxa occur in isolated parts of northern
Mexico and have not been well studied [18]. Very little is known about
morphological characteristics used to delineate these groups.
Controversy still surrounds the five most widely recognized subspecies.
The subspecies whipplei was formerly known as typica [13], and some
confusion still exists in older published accounts. McKelvey [28]
considered typica and parishii to warrant recognition as varieties
rather than as subspecies, although many later researchers delineated
them as valid subspecies. Researchers have noted much variation
throughout all subspecies and hint that many morphological
characteristics are not "taxonomically reliable" [13]. However, many
taxonomists recommend maintaining these five subspecies for the
following reasons [18]:
(1) each entity occupies a fairly definite geographic area
(2) individual morphological characteristics are variable, but
overall, statistically different morphs do exist
(3) all are in common use in the literature
Clearly, much more research is needed to fully document variation of
this species and to determine appropriate taxonomic relationships.
LIFE FORM :
Shrub
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
COMPILED BY AND DATE :
D. Tirmenstein, April 1989
LAST REVISED BY AND DATE :
NO-ENTRY
AUTHORSHIP AND CITATION :
Tirmenstein, D. A. 1989. Yucca whipplei. In: Remainder of Citation
DISTRIBUTION AND OCCURRENCE
SPECIES: Yucca whipplei | Our Lord's Candle
GENERAL DISTRIBUTION :
Our Lord's candle occurs from coastal southern California across
portions of the Mohave Desert southward into Mexico and northeast to
Arizona [24,40,41,45]. Distribution of subspecies is as follows:
ssp. caespitosa--occurs along the edge of the Mohave Desert from the San
Bernardino Mountains to Walker Pass and along the
western base of the southern Sierra Nevada. A slender
form of this subspecies occurs along the Kern and King
rivers in California [31].
ssp. intermedia--occurs near the Coast in the Santa Monica and Santa
Susanna mountains of Ventura and Los Angeles counties [31].
ssp. parishii--occurs along the coastal slopes of the San Gabriel and
San Bernardino mountains [17,31].
ssp. percursa--occurs from Monterey County to Santa Barbara County; is
particularly common in the Santa Ynez Mountains of
southern California [31].
ssp. whipplei--occurs from Riverside and Orange counties in California
southward into Mexico [31].
ECOSYSTEMS :
FRES21 Ponderosa pine
FRES30 Desert shrub
FRES34 Chaparral - mountain shrub
FRES35 Pinyon - juniper
STATES :
CA MEXICO
ADMINISTRATIVE UNITS :
LAME PINN SAMO
BLM PHYSIOGRAPHIC REGIONS :
3 Southern Pacific Border
7 Lower Basin and Range
KUCHLER PLANT ASSOCIATIONS :
K005 Mixed conifer forest
K023 Juniper - pinyon woodland
K033 Chaparral
K035 Coastal sagebrush
K041 Creosotebush
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 :
NO-ENTRY
HABITAT TYPES AND PLANT COMMUNITIES :
Our Lord's candle is listed as a dominant in a number of coastal sage
scrub or chapparal communities of southern California. Common
codominants include California broomsage (Lepidospartum squamatum),
thickleaf yerba-santa (Eriodycton crassifolium), and California
sagebrush (Artemisia californica) [33].
VALUE AND USE
SPECIES: Yucca whipplei | Our Lord's Candle
WOOD PRODUCTS VALUE :
NO-ENTRY
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
The flowers and fruits of Our Lord's candle are used by a number of
small birds and mammals [2,9]. This species provides little browse for
domestic livestock or wild ungulates [9], although some use of the
flowers has been reported [1]. It presumably provides some cover for
smaller birds and mammals.
PALATABILITY :
Fruits of Our Lord's candle 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
locations [1].
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 :
NO-ENTRY
VALUE FOR REHABILITATION OF DISTURBED SITES :
Little documentation exists on the potential value of Our Lord's candle
for rehabilitation. Studies indicate that seedlings can be successfully
transplanted [45]. However, Webber [45] 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 [12]. The flowers of Our Lord's candle are sometimes made
into various novelty products [45].
MANAGEMENT CONSIDERATIONS :
NO-ENTRY
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Yucca whipplei | Our Lord's Candle
GENERAL BOTANICAL CHARACTERISTICS :
Our Lord's candle is a highly variable, rosette-forming, perennial shrub
[23,45]. Subspecies are distinguished by growth form (caespitose or
solitary) and color, size, and shape of leaves and flowers [10,13,17].
The five subspecies also differ in phenological development, fruit set,
and growth habit. The life history of each subspecies is distinct,
although varying forms do occur in most populations [23]. A correct
determination of the subspecies is important in explaining differences
in regenerative strategies, and variability in plant response to fire,
herbicides, or mechanical disturbance. Descriptions of the various
subspecies follow:
Subspecies caespitosa: The stem branches from above the ground to form
a large, crowded clump of numerous, clustered rosettes, with numerous
secondary rosettes forming in the seedling stage. The plant fruits for
many years, producing several flowerstalks each spring. Flowerstalks
average 8 feet (2.5 m); leaves are quite rigid and average 2.6 feet (8
dm) in length; flowers are creamy white [18,31,45].
Subspecies intermedia: This subspecies is similar to ssp. caespitosa in
that it lives for many years and forms a dense clump of rosettes.
However, the clumps are relatively small, and the plant usually only
forms one inflorescence in a season. After flowering, secondary
rosettes are formed near the base of old flowerstalks, apparently
arising from adventitious axillary buds. Flowerstalks average 10 feet
(3 m). Leaves are flat, somewhat more rigid than those of ssp.
caespitosa, and average 3 feet (1 m) long [17,31,45].
Subspecies parishii: This subspecies grows as a solitary stem and
produces no offshoots; it dies after fruit has formed [13,17,31]. It is
the tallest subspecies of Our Lord's candle, growing from 7 to 21 feet
(2.1-6.4 m) in height [17]. Leaves are flat, flexible, and average 3
feet (1 m) in length [17,31]. After flowering, plants are reduced to a
dried, fibrous base 6 to 8 inches (15-20 cm) across, which often
persists for a number of years [10].
Subspecies percursa: The stem branches by means of undergound rhizomes
to from large, fairly open clumps made up of distinct rosettes and
rosette clusters [42]. After flowering, the secondary rosettes
sometimes produce adventitious axillary rosettes [17]. Leaves are
shorter than those of other subspecies (approximately 2 feet [4.8 dm])
and quite rigid [18,31]. The stem grows to 1 to 2 feet (3-6 dm) in
height [17,31]. Subspecies percursa flowers and fruits for many years
before the plant reaches maturity [45]. Creamy-white flowers are borne
on a flowerstalk approximately 9 feet (3 m) tall [31].
Subspecies whipplei: This subspecies is an acaulescent, monocarpic
perennial [1,13,31,42]. The flexible leaves grow 1 to 3 feet (30-80 cm)
in length and form a dense, basal rosette [18,31]. A single, simple
flowerstalk grows to 7 or 8 feet (2-2.5 m) in height [31]. The stem
produces no offshoots [13]. The flowers are white or purple-tinged
[17,31,42]. After flowering, plants are reduced to a resistant fibrous
base, 6 to 8 inches (15-20 cm) across, which often persists for several
years [10].
RAUNKIAER LIFE FORM :
Geophyte
Therophyte
REGENERATION PROCESSES :
Regeneration in Our Lord's candle varies greatly according to
subspecies. Subspecies whipplei and parishii are semelparous and
distinguished primarily by size; ssp. caespitosa is an iteroparous
perennial; ssp. percursa has vegetative reproduction; and ssp.
intermedia combines both patterns [23]. Although each subspecies
exhibits a typical mode of reproduction associated with the predominant
growth habit, in most populations some individuals employ different
regenerative strategies. Many populations have mixtures of monocarpic,
caespitose, and rhizomatous growth forms [23].
Flowering and fruiting: Attractive, creamy-white or sometimes
purplish-tinged flowers are borne on flowerstalks which generally grow 8
to 10 feet (2.5-3 m) in height (7 to 21 feet [2-6 m] for ssp. parishii)
[45]. The inflorescence is a pedant panicle made up of one hundred to
several thousand flowers [40]. The showy inflorescence of ssp. parishii
is approximately twice as large (averaging 6.5 feet in length and 2 feet
in diameter) as that of ssp. whipplei (averaging 3 feet in length and 13
inches in diameter) [17]. The lower portion of the panicle develops
fruit while the upper part is still flowering [40]. Each dehiscent
fruit contains approximately 150 to 200 flat, smooth, dull black seeds,
which are dispersed by wind [40,45].
Germination: Seed of ssp. percusa is the heaviest in the taxon and
exhibits the best germination [23], while seed of ssp. parishii is the
lightest and exhibits the poorest germination [23]. Overall germination
of Our Lord's candle is variable, ranging from 0 to 100 percent in
controlled laboratory experiments [4]. When viability is high,
germination may be rapid. Germination of seed presoaked in water for 24
hours began within 3 days of treatment [42]. Despite the occurrence of
Our Lord's candle in fire-prone chaparral and the importance of sexual
regeneration in most subspecies, seed is vulnerable to high
temperatures. Significant reductions in germination have been noted
after even brief exposure to high temperatures [18].
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. Our Lord's candle relies solely on the
yucca moth (Tegeticula maculata), which consumes a small percentage of
flowers while in the larval stage, for pollination [3]. 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 Our Lord's candle reflect competition for potentially
scarce pollinators [40].
Vegetative: Subspecies caespitosa regenerates vegetatively by producing
multiple, densely packed rosettes from axillary buds early in
development; these rosettes are attached to a small caudex [23]. This
mode of regeneration allows this subspecies to persist or increase even
on harsh sites. Subspecies caespitosa rarely, if ever, forms rhizomes
[23,45]. Subspecies intermedia regenerates vegetatively via axillary
branching, which occurs only after it is well matured; the base of the
stem and roots persist after flowering to form the subterranean portion
of the new plants [13,17]. Subspecies percusa reproduces 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 :
Although some overlap does occur, each subspecies of Our Lord's candle
occupies its own characteristic habitat:
Subspecies caespitosa grows from 1,800 to 4,000 feet (549-1,219 m) [45]
in areas now dominated by relatively severe continental weather patterns
[18]. This subspecies commonly occurs as an understory species in
California juniper (Juniperus californica) woodlands, and in desert
shrub and chaparral communities [17,31,45].
Subspecies intermedia grows from sea level to 2,000 feet (0-610 m) in
California coastal sage and chaparral [17,31]. It most typically occurs
in areas described as transitional to primarily maritime and continental
influences [18].
Subspecies parishii grows across a broad elevational range occurring
from 1,000 to 8,000 feet (305-2,438 m) [31]. It grows particularly well
on mountain slopes and alluvial fans [31]. This subspecies extends from
chaparral and coastal sage into ponderosa pine (Pinus ponderosa) montane
forests of California [17,31].
Subspecies percursa most commonly occurs on bare, rocky, mountain slopes
or mesas from sea level to 3,608 feet (0-1,100 m) [21,23,45]. It grows
in coastal sage and chaparral communities of southern California
[17,31], environments somewhat more maritime than those occupied by
other subspecies of Our Lord's candle [18].
Subspecies whipplei most commonly grows on dry, stony slopes in
foothills, coastal plains, mountains, and desert fringes of southern
California and Mexico [2,31]. It occurs from 100 to 4,920 feet
(30-1,500 m) [21,31,] in chaparral, coastal sage, and desert shrub
communities [17,31]. This subspecies is now generally found in areas
characterized by a relatively mild, mesic climate [18].
Soils: All subspecies grow well on a variety of soil types including
unconsolidated or granitic substrates [24]. Growth is most common on
very porous, shallow soils or on rocky outcrops [17].
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
(Eriodycton 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) [40].
SUCCESSIONAL STATUS :
The successional role of Our Lord's candle 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 availabilty or aberrant
weather patterns.
Flowering: Individual plants flower for 2 to 7 weeks [1], 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 [10]. Our Lord's candle may only
bloom for 10 days on very dry sites, while plants on more mesic sites
flower for up to 30 days [40]. Each flower on the inflorescence is only
open for a few days [1]. 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 [42]. Fruit set tends to be low, but is somewhat
higher in fruit at the bottom of the panicle [14]. Fruits reach full
size within a month; seed pods mature, turning dry and gray-brown, by
late summer or fall [40]. The first pods dehisce while the last flowers
are wilting [3]. Wind dispersal usually begins by mid-August [10].
The monocarpic subspecies whipplei and parishii turn brown and die by
late summer or fall in the year of flowering [10]. These plants
generally complete their life cycle within 4 to 7 years [10,28].
FIRE ECOLOGY
SPECIES: Yucca whipplei | Our Lord's Candle
FIRE ECOLOGY OR ADAPTATIONS :
The specific fire adaptations of Our Lord's candle vary greatly
according to subspecies. Even individuals within a given population may
exhibit varying adaptations to fire. Typical regenerative strategies of
each subspecies may represent evolutionary adaptations to the fire
frequency most common in the habitat occupied by that taxon. Genetic
variation present within populations may have allowed Our Lord's candle
to persist or spread despite climatic shifts leading to changes in fire
frequency or subsequent geographic isolation.
Our Lord's candle is generally well adapted to persist in fire-prone
environments, and is closely associated with chaparral types
(particularly ssp. whipplei and ssp. parashii) [43]. However, Our
Lord's candle often grows in openings within chaparral communities where
fuel levels are lower than those of surrounding areas [10]. 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 [36].
Fairly vigorous resprouting has been noted after many fires
[29,35,38,38], but in other instances, little if any resprouting has
occurred and high mortality has been observed [20]. 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 Our Lord's candle are generally not
conducive to seedling germination and establishment [18]. Subspecific
variation may be extremely important in explaining differences in fire
adaptations. Thus, correct identification of subspecies is essential
when considering specific fire adaptations.
Of the five subspecies, ssp. whipplei and parashii are ones most closely
associated with the fire-prone chaparral. They exhibit a larger leaf
area which may allow for more rapid growth rates in fire-free years, a
characterisdtic of selective value in fire-prone habitats [23]. Also,
although seed of Our Lord's candle is in general very sensitive to heat
damage, seeds of these two subspecies are more resistant to exposure to
high temperatures (up to 230 degrees Fahrenheit [110 deg C]) than are
seed of the other subspecies [23]. Reestablishment is probably through
surviving on-site or off-site wind-dispersed seed.
The rhizomes of ssp. percursa vary in depth, length, and thickness but
are probably well protected from fire by overlying soil. This
subspecies is probably capable of resprouting rapidly after fire. Many
of the populations of Our Lord's candle which have been observed to
resprout vigorously and rapdily, even after fires of high intensity, may
be representatives of this subspecies. Postfire resprouting is much
more important than reestablishment through seed for this subspecies.
Subspecies caespitosa would probably be killed by fires that removed
aboveground vegetation, with reestablishment through off-site seed
likely. However, its caespitose growth form may promote survival in
areas experiencing lighter fires. Undamaged or slightly damaged
portions of the clump would survive and resume growth, permitting fairly
rapid reestablishment. The seed of this subspecies is very sensitive to
fire [23].
Subspecies intermedia typically grows 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 ssp. intermedia can survive and resume growth, particularly
after lighter fires.
POSTFIRE REGENERATION STRATEGY :
Secondary colonizer - off-site seed
Rhizomatous shrub, rhizome in soil
FIRE EFFECTS
SPECIES: Yucca whipplei | Our Lord's Candle
IMMEDIATE FIRE EFFECT ON PLANT :
The effect of fire on Our Lord's candle probably varies according to
such factors as fire intensity and severity, climate, site
characteristics, and genetic makeup of a particular subspecies or
population. Although major differences between subspecies have been
documented with respect to botanical characteristics and regenerative
strategies, little is known about the effect of fire on each subspecies.
Few researchers have identified plants to subspecies when reporting fire
effects. Consequently the literature appears variable and highly
contradictory. Some researchers have observed low postfire mortality of
Our Lord's candle (< 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
regenerative strategies.
Postfire mortality is probably high in semelparous, monocarpic
subspecies such as whipplei and parashii. A fire which consumes
aboveground vegetation would presumably kill the plant, although some
individuals might survive if the foliage was only lightly damaged.
The effects of fire on iteroparous subspecies such as caespitosa and
intermedia are largely unknown. However, survival is probably somewhat
more likely that in monocarpic subspecies, since they have the ability
to survive and regrow if portions of the dense clump or clone reamin
undamaged. Subspecies intermedia froms 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. Thus, season of burn may be particularly important
in determining the effect of fire on this subspecies.
Postfire mortality is presubably low in ssp. percursa 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 :
NO-ENTRY
PLANT RESPONSE TO FIRE :
Postfire response of Our Lord's candle is extremely variable. Each
subspecies presumably exhibits a characteristics response to fire, but
this diverse species shows extreme variability and many growth forms can
be observed in a single population. The entire suite of postfire
responses by subspecies has not been well documented. More research is
clearly needed to sort out the complex interrelationships between
genetic and environmental factors which influence postfire regenerative
strategies.
Postfire response of Our Lord's candle may be rapid. Sprouts or
seedlings appeared within 2 years after a September fire removed all
aboveground vegetation [8]. 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, resprout 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" [9]. Limited evidence
suggests that where Our Lord's candle is capable of resprouting, this
mode of regeneration allows for much more rapid and complete recovery
than would be expected in populations which regenerate through seed
alone [27]. In many instances, Our Lord's candle 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 [9].
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
Recovery: Vegetative regeneration of Our Lord's candle through
resprouting 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 California coastal sage community is as follows [27]:
site # % cover (#/ha) mean size (cm sq)
resprout seedling resprout 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 Our Lord's candle cover through seed alone may take
more than 4 years in many southern California chaparral communities
[19].
Although evidence is lacking, the likelihood of vegetative regeneration
in subspecies or individuals capable of such a response may depend
largely on fire severity. Conrad [9] 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, postburn productivity ranged from 0.05 pounds per acre (57
g/hectare) in winter to 11 pounds per acre (1,196 g/hectare) in spring
[37,38].
REFERENCES
SPECIES: Yucca whipplei | Our Lord's Candle
REFERENCES :
1. Aker, Charles L. 1982. Regulation of flower, fruit and seed production
by a monocarpic perennial, Yucca whipplei. Journal of Ecology. 70:
357-372. [5842]
2. Aker, Charles L. 1982. Spatial and temporal dispersion patterns of
pollinators and their relationship to the flowering strategy of Yucca
whipplei (Agavaceae). Oecologia. 54(2): 243-252. [5760]
3. Aker, C. L.; Udovic, D. 1981. Oviposition and pollination behavior of
the yucca moth, and its relation to the reproductive biology of Yucca
whipplei (Agavaceae). Oecologia. 49(1): 96-101. [5807]
4. Arnott, Howard J. 1962. The seed, germination, and seedling of yucca.
Berkeley, CA: University of California Press. 96 p. [4317]
5. Krueger, William C.; Sharp, Lee A. 1978. Management approaches to reduce
livestock losses from poisonous plants on rangelands. Journal of Range
Management. 31(5): 347-350. [1379]
6. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals,
reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's
associations for the eleven western states. Tech. Note 301. Denver, CO:
U.S. Department of the Interior, Bureau of Land Management. 169 p.
[434]
7. Brockway, Dale G.; Topik, Christopher; Hemstrom, Miles A.; Emmingham,
William H. 1985. Plant association and management guide for the Pacific
silver fir zone: Gifford Pinchot National Forest. R6-Ecol-130a.
Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific
Northwest Region. 122 p. [525]
8. Christensen, Norman L.; Muller, Cornelius H. 1975. Effects of fire on
factors controlling plant growth in Adenostoma chaparral. Ecological
Monographs. 45: 29-55. [4923]
9. Conrad, C. Eugene. 1987. Common shrubs of chaparral and associated
ecosystems of southern California. Gen. Tech. Rep. PSW-99. Berkeley, CA:
U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest
and Range Experiment Station. 86 p. [4209]
10. Cox, George W. 1981. The yucca with the big bang. Environment Southwest.
493: 12-16. [5762]
11. Cronquist, Arthur; Holmgren, Arthur H.; Holmgren, Noel H.; [and others].
1977. Intermountain flora: Vascular plants of the Intermountain West,
U.S.A. Vol. 6. The Monocotyledons. New York: Columbia University Press.
584 p. [719]
12. Dale, Nancy. 1986. Flowering plants: The Santa Monica Mountains, coastal
and chaparral regions of southern California. Santa Barbara, CA: Capra
Press. In coooperation with: The California Native Plant Society. 239 p.
[7605]
13. DeMason, Darleen A. 1984. Offshoot variability in Yucca Whipplei subsp.
percursa (Agavaceae). Madrono. 31(4): 197-202. [5803]
14. Doust, Jon L.; Doust, Lesley L. 1983. Parental strategy: gender and
maternity in higher plants. BioScience. 33(3): 180-185. [5805]
15. Eyre, F. H., ed. 1980. Forest cover types of the United States and
Canada. Washington, DC: Society of American Foresters. 148 p. [905]
16. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others].
1977. Vegetation and environmental features of forest and range
ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of
Agriculture, Forest Service. 68 p. [998]
17. Haines, Lee. 1941. Variation in Yucca whipplei. Madrono. 6: 33-45.
[5763]
18. Hoover, Doris Anne. 1973. Evidence from population studies for two
independent variation patterns in Yucca whipplei Torrey. Northridge, CA:
California State University, Northridge. 145 p. M.S. thesis. [6076]
19. Keeley, Jon E.; Keeley, Sterling C. 1981. Post-fire regeneration of
southern California chaparral. American Journal of Botany. 68(4):
524-530. [4660]
20. Keeley, Jon E.; Keeley, Sterling C. 1984. Postfire recovery of
California coastal sage scrub. American Midland Naturalist. 111(1):
105-117. [5587]
21. Keeley, Jon E.; Keeley, Sterling C.; Ikeda, Diane A. 1986. Seed
predation by yucca moths on semelparous, iteroparous, and vegetatively
reproducing subspecies of Yucca whipplei (Agavaceae). American Midland
Naturalist. 115(1): 1-9. [5819]
22. Keeley, Jon E.; Meyers, Adriene. 1985. Effect of heat on seed
germination of southwestern Yucca species. Southwestern Naturalist.
30(2): 303-304. [5761]
23. Keeley, Jon E.; Tufenkian, Dav. 1984. Garden comparison of germination
and seedling growth of Yucca whipplei subspecies (Agavaceae). Madrono.
31(1): 24-29. [5801]
24. Kirkpatrick, J. B.; Hutchinson, C. F. 1977. The community composition of
Californian coastal sage scrub. Vegetatio. 35(1): 21-33. [5612]
25. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation
of the conterminous United States. Special Publication No. 36. New York:
American Geographical Society. 77 p. [1384]
26. Lyon, L. Jack; Stickney, Peter F. 1976. Early vegetal succession
following large northern Rocky Mountain wildfires. In: Proceedings, Tall
Timbers fire ecology conference and Intermountain Fire Research Council
fire and land management symposium; 1974 October 8-10; Missoula, MT. No.
14. Tallahassee, FL: Tall Timbers Research Station: 355-373. [1496]
27. Malanson, George P.; O'Leary, John F. 1982. Post-fire regeneration
strategies of Californian coastal sage shrubs. Oecologia. 53: 355-358.
[3490]
28. McKelvey, Susan Delano. 1938. Yuccas of the southwestern United States:
Part one. Jamaica Plains, MA: The Arnold Arboretum of Harvard
University. 147 p. [3902]
29. Mills, James N. 1986. Herbivores and early postfire succession in
southern California chaparral. Ecology. 67(6): 1637-1649. [5405]
30. Munz, Philip A. 1973. A California flora and supplement. Berkeley, CA:
University of California Press. 1905 p. [6155]
31. Munz, Philip A. 1974. A flora of southern California. Berkeley, CA:
University of California Press. 1086 p. [4924]
32. National Academy of Sciences. 1971. Atlas of nutritional data on United
States and Canadian feeds. Washington, DC: National Academy of Sciences.
772 p. [1731]
33. Paysen, Timothy E.; Derby, Jeanine A.; Black, Hugh, Jr.; [and others].
1980. A vegetation classification system applied to southern California.
Gen. Tech. Rep. PSW-45. Berkeley, CA: U.S. Department of Agriculture,
Forest Service, Pacific Southwest Forest and Range Experiment Station.
33 p. [1849]
34. Raunkiaer, C. 1934. The life forms of plants and statistical plant
geography. Oxford: Clarendon Press. 632 p. [2843]
35. Sauer, Jonathan D. 1977. Fire history, environmental patterns, and
species patterns in Santa Monica Mountain chaparral. In: Mooney, Harold
A.; Conrad, C. Eugene, technical coordinators. Proceedings of the symp.
of the environmental consequences of fire and fuel management in
Mediterranean ecosystems; 1977 August 1-5; Palo Alto, CA. Gen. Tech.
Rep. WO-3. Washington, DC: U.S. Department of Agriculture, Forest
Service: 383-386. [4866]
36. Simpson, Philip George. 1975. Anatomy and morphology of the Joshua tree
(Yucca brevifolia): an arborescent monocot. Santa Barbara, CA:
University of California. 524 p. Dissertation. [6280]
37. Tratz, Wallace Michael. 1978. Postfire vegetational recovery,
productivity, and herbivore utilization of a chaparral-desert ecotone.
Los Angeles, CA: California State University. 133 p. Thesis. [5495]
38. Barry, W. James. 1984. Management and protection of riparian ecosystems
in the state park system. In: Warner, Richard E.; Hendrix, Kathleen M.,
eds. California riparian systems: Ecology, conservation, and productive
management. Berkeley, CA: University of California Press: 758-766.
[5873]
39. U.S. Department of Agriculture, Soil Conservation Service. 1982.
National list of scientific plant names. Vol. 1. List of plant names.
SCS-TP-159. Washington, DC. 416 p. [11573]
40. Udovic, Daniel. 1981. Determinants of fruit set in Yucca whipplei:
reproductive expenditure vs. pollinator availability. Oecologia. 48(3):
389-399. [5794]
41. Udovic, Daniel. 1986. Floral predation of Yucca whipplei (Agavaceae) by
the sap beetle Anthonaeus agavensis (Coleoptera: Nitidulidae).
Pan-Pacific Entomologist. 62(1): 55-57. [5766]
42. Udovic, Daniel; Aker, Charles. 1981. Fruit abortion and the regulation
of fruit number in Yucca whipplei. Oecologia. 49(2): 245-248. [5793]
43. Vogl, Richard J. 1967. Fire adaptations of some southern California
plants. In: Proceedings, Tall Timbers fire ecology conference; 1967
November 9-10; Hoberg, California. No. 7. Tallahassee, FL: Tall Timbers
Research Station: 79-109. [6268]
44. Vogl, Richard J.; Schorr, Paul K. 1972. Fire and manzanita chaparral in
the San Jacinto Mountains, California. Ecology. 53(6): 1179-1188.
[5404]
45. Webber, John Milton. 1953. Yuccas of the Southwest. Agriculture
Monograph No. 17. Washington, DC: U.S. Department of Agriculture, Forest
Service. 97 p. [2474]
46. Webber, John M. 1960. Hybridization and instability of Yucca. Madrono.
15: 187-192. [5764]
47. Wells, Philip V.; Woodcock, Deborah. 1985. Full-glacial vegetation of
Death Valley, California: juniper woodland opening to Yucca semidesert.
Madrono. 32(1): 11-23. [2493]
48. Zedler, Paul H. 1981. Vegetation change in chaparral and desert
communities in San Diego County, California. In: West, D. C.; Shugart,
H. H.; Botkin, D. B., eds. Forest succession: Concepts and application.
New York: Springer-Verlag: 406-430. [4241]
Index
Related categories for Species: Yucca whipplei
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