|Image copyright © Lee Dittmann; used with permission.|
Populations of Chlorogalum
pomeridianum var. divaricatum and C. p. var. minus are documented
only in California. Chlorogalum p. var. pomeridianum
occurs in California and Oregon .
FRES21 Ponderosa pine
FRES28 Western hardwoods
FRES34 Chaparral-mountain shrub
FRES42 Annual grasslands
STATES/PROVINCES: (key to state/province abbreviations)
The shrub layer where soap plant occurs is dominated by 1 or more of the following species: wedgeleaf ceanothus (Ceanothus cuneatus), manzanita spp. (Arctostaphylos spp.), eastern Mojave buckwheat (Eriogonum fasciculatum), common snowberry, oceanspray (Holodiscus discolor), cluster rose (Rosa pisocarpa), pale serviceberry (Amelanchier pallida), and poison-oak (Toxicodendron diversilobum) [22,56].
Herbaceous species occurring with soap plant are brome spp. (Bromus spp.), rattail sixweeks grass (Vulpia myuros), ripgut brome (Bromus diandrus), California brome (B. carinatus), western sword fern (Polystichum munitum), yerba buena (Clinopodium douglasii), woodland strawberry (Fragaria vesca), mountain sweetroot (Osmorhiza berteroi), Pacific blacksnakeroot (Sanicula crassicaulis), American vetch (Vicia americana), Columbian larkspur (Delphinium trolliifolium), licorice fern (Polypodium glycyrrhiza), bigflower tellima (Tellima grandiflora), false carrot (Yabea microcapra), catchweed bedstraw (Galium aparine), Indian pink (Silene californica), cucamonga manroot (Marah macrocarpus), and prettyface (Triteleia ixioides ssp. scabra) [22,56].
Soap plant is not documented as an indicator or a dominant species in vegetation types for California and Oregon. It is most commonly associated with chamise chaparral and oak woodland plant communities [22,56], but is also known to occur in evergreen forests . Vegetation classifications for communities where soap plant is a component species follow:
knobcone pine (Pinus attenuata) communities 
purple needlegrass (Nassella pulchra) associations south and east of Monterey 
abundant in chamise (Adenostoma fasciculatum) brushlands 
Bald Hills oak woodlands, Redwood National Park:
Soap plant showed 0.78% frequency in a Oregon white oak/common snowberry (Quercus garryana/Symphoricarpos albus var. laevigatus) community, and showed 0.83% frequency in the Oregon white oak/orchard grass (Dactylis glomerata) community on mesic, lower concave slopes. It occurred in a mockorange/brittle bladder-fern (Philadelphus lewisii/Cystopteris fragilis) community occurring in a stream channel community with a dense shrub layer, soap plant had 0.50% frequency. Soap plant had 0.75% frequency in a Sierra gooseberry/varileaf phacelia (Ribes roezlii/Phacelia heterophylla) community, a rock outcrop type with a moderately dense shrub layer. Soap plant had 1 to 5% cover in all of these bald hill communities .
Pinnacles National Monument: Soap plant occurred in chamise chaparral with 3% mean cover and 16.7% mean frequency .
Ring Mountain Preserve, Marin County: Soap plant was frequently encountered in the serpentine bunchgrass community (typified by many boulders strewn among perennial grasses and bulbous plant species), with 9.48% average frequency on north and south slopes and on ridgetops. It had 0.84% frequency in the nonnative annual grassland community. Soap plant had 3.3% cover in the northern coyote bush (Baccharis pilularis) community (characterized by grassland slopes), and had frequency of 6.47% in the freshwater seep community (characterized by the presence of surface water, although some drainages typically dry completely by June) .Santa Ana Mountains: On a knobcone pine serpentine site, soap plant occupied exposed sites with 7% cover, but was not found on surrounding chaparral .
|Image copyright © Lee Dittmann; used with permission.|
GENERAL BOTANICAL CHARACTERISTICS:
The following description of soap plant provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available [25,38,39].
Soap plant is a native, perennial forb. The plant has a basal tuft of wavy, 1-inch (2.5 cm) wide, linear leaves. The leaves are flaccid and stretch along the ground up to 18 inches (46 cm). The liliaceous, star-like flowers of soap plant have 3 sepals and 3 petals and are borne on a leafless, paniculate inflorescence composed of racemose axes. The inflorescence can reach heights up to 6 feet (1.8 m). The flowers are vespertine (opening or blooming in the evening) and ephemeral [11,12,13,27,28,38]. There can be up to 200 flowers per plant . The fruit is a capsule . Soap plant seeds are large and black, numbering 1 or 2 per locule . The bottle-shaped bulb of soap plant is 3 to 6 inches (7-15 cm) long and 1 to 3 inches (3-8 cm) wide. It is densely covered with persistent dark brown fibers [11,12,39]. It is buried at a depth of 4 to 12 inches (10-30 cm). Burial is achieved over several growing seasons, as the bulb has contractile roots that continually pull it downward .RAUNKIAER  LIFE FORM:
Pollination: There is only a small window of time in which the flowers of soap plant can be pollinated, since the flowers open for only a few hours on only 1 day. They open rapidly in the late afternoon, produce nectar and deliquesce some 6 to 8 hours later, whether pollination takes place or not [27,52]. Large bees (honeybees, carpenter bees, and 2 species of bumblebee) are apparently the only effective pollinators. Rare or infrequent visits are made by yellow jackets, mining bees (Lasioglossum sisymbrii), and Allen's hummingbirds . Sphingid moths are noted to visit the soap plant flowers after dark . Removal of the shrub layer and the subsequent increase in light availability may enhance pollination after fire (see Fire adaptations) .
Breeding system: A study by Stockhouse and Wells  showed that soap plants are self-compatible; however, this does not mean self-fertilization occurs naturally in the species. It is still dependent upon pollinators to transfer pollen to the stigmatic surface for fertilization to take place in the field [28,52].
Seed production: Flowering and seed production increase after fire, allowing the use of the available mineral seed bed and thereby enhancing soap plant seedling establishment . In California chaparral, most geophytes produce nondormant seeds in the 1st year after fire . Seed is not set in the absence of an animal pollinator .
Seed dispersal: The mode of dispersal of the soap plant is autochory, dispersal by the plant itself. Seeds are large, unspecialized for dispersal, and depend on factors such as gravity .
Seed banking: Following fire, soap plant emerges as part of the plant community, possibly from a seed supply that has lain dormant since the last fire .
Germination: The seeds of soap plant are nonrefractory: germination is not stimulated by high temperatures; instead, the seeds are sensitive to high temperatures [32,57]. Seeds are immediately germinable typically germinating readily upon wetting, and incubating under moderate temperatures . Experimental findings suggest that soap plant seeds generally germinate approximately 7 days after imbibition . Contradicting evidence produced in experimental laboratory studies showed that seeds of soap plant germinated only after being stratified at 41 ºF (5º C) for 60 days .
Seedling establishment/growth: In California chaparral, seedling establishment for most geophytes, like soap plant, takes place in the 2nd postfire year, when light and nutrient levels remain high but shrub competition, herbivory, and seed predation are still low . In order to survive summer drought seedlings must develop rapidly to insure an adequate root system and underground storage organ .
Asexual regeneration: Soap plant sprouts after fire from deeply buried bulbs . Bulbs may be dormant for 10 or more years under adverse conditions such as drought, sprouting when conditions are favorable .SITE CHARACTERISTICS:
The climate in which soap plant thrives is described as mediterranean , with cool, wet winters and warm, dry summers . The mean annual precipitation ranges from 16 to 20 inches (410 -510 mm) .
The following table provides elevations where soap plant has been collected.
|California||below 5,000 feet (1,524 m) [25,38,52]|
|Elk Creek Drainage (Sequoia National Park)||2,100 feet (640 m) |
|Hastings Natural History Reservation, San Lucia Coastal Range, Monterey County||860 to 3,600 feet (262-1,050 m) |
|central Sierra Nevada||up to 6,000 feet (1,800 m) |
|Pinnacles National Monument||1,200 to 3,000 feet (370-910 m) |
|Donald and Sylvia McLaughlin University of California Natural Preserve||1,200 to 3,100 feet (370-950 m) |
|Santa Ana Mountains||average 3,500 feet (1,100 m) |
|Oregon||below 5,000 feet (1,524 m) |
Fire regimes: Soap plant occurs in a narrow range of fire regimes. Chaparral communities, where soap plant is common, sustain frequent, stand-replacing fires. The high frequency of fire in chaparral communities suggests that soap plant has evolved with fire. The oak woodland and low-elevation ponderosa pine communities, in which soap plant also occurs, historically had frequent, low-severity fires. In ponderosa pine and some oak communities, low-severity surface fires are being replaced by high-severity, long-interval fires .
The following table provides fire return intervals for plant communities and ecosystems where soap plant is important. For further information, see the FEIS review of the dominant species listed below.
|Community or ecosystem||Dominant species||Fire return interval range (years)|
|California chaparral||Adenostoma and/or Arctostaphylos spp.||<35 to <100|
|coastal sagebrush||Artemisia californica||<35 to <100|
|California montane chaparral||Ceanothus and/or Arctostaphylos spp.||50-100 |
|California steppe||Festuca-Danthonia spp.||<35 [40,55]|
|Jeffrey pine||Pinus jeffreyi||5-30|
|Pacific ponderosa pine*||Pinus ponderosa var. ponderosa||1-47|
|California mixed evergreen||Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii||<35|
|California oakwoods||Quercus spp.||<35 |
|coast live oak||Quercus agrifolia||2-75 |
|canyon live oak||Quercus chrysolepis||<35 to 200|
|blue oak-foothills pine||Quercus douglasii-P. sabiniana||<35|
|Oregon white oak||Quercus garryana||<35 |
|California black oak||Quercus kelloggii||5-30 |
Soap plant's response to fire has been thoroughly documented in chaparral, where it is most commonly found. Sweeney  states that soap plant increases in numbers 2 to 3 years after fire. Sampson  ranks soap plant as fairly to very abundant on recently burned chaparral, peaking the 2nd postfire year and declining but persisting 3, 4, and 5 years after fire in chamise and manzanita/ceanothus communities. Barbour and others  convey that soap plant populations remain constant/persistent up to 4 years after fire.FIRE MANAGEMENT CONSIDERATIONS:
Although livestock use of soap plant is not documented, it can be assumed that if soap plant is an available food source, it would be consumed. This is concluded from a study done on the Hastings Natural History Reservation and the Santa Lucia Coastal Range in Monterey County, where soap plant only appeared in uncultivated (unfarmed and ungrazed) stands .
Palatability/nutritional value: Studies done to date (2006) show that ground squirrels, pocket gophers, other rodents, rabbits, and mule deer consume young plants, seeds, and inflorescences of soap plant [14,26,33,42], suggesting that palatability is good.
Cover value: No information is available on this topic.VALUE FOR REHABILITATION OF DISTURBED SITES:
Native Americans offered and introduced soap plant to early missionaries and explorers . There are several traditional uses of soap plant. Fibers from the bulb portion of the plant were used to stuff mattresses and also used for brushes [11,12,58]. The leaves, which are flexible and half-succulent, were used to cover bread dough while baking. The leaves can also be pricked into the skin to form green tattoo marks . The bulb was used for both food and utensils . The bulb contains saponin, a soap substitute . The bulbs are crushed and used as soap for clothes and bathing. When the bulb and young shoots are cooked, a resinous substance is exuded that was used as a glue for arrows [11,12]. The roasted bulb is used antiseptically as a poultice for sores. The Wailakis used it on the body for cramps and for rheumatism. A decoction of the bulb is also used as a diuretic and laxative .
Although illegal today, Native Americans used to crush soap plant bulbs and rub them into a lather. The lather was then thrown into streams and ponds to stun and stupefy fish, causing them to float to the top of the water where they were easily caught [11,12].OTHER MANAGEMENT CONSIDERATIONS:
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