These unusual bulbs grow wild in the dry, rocky hillsides north and west of Palomar College, in an endangered plant community known as coastal sage scrub. In the tradition of Noteworthy Plants, they have intrigued biology and botany students of Mr. Wolffia for many decades.
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Introduction
The Lily Family (Liliaceae) includes about
300 genera and 4600 species distributed throughout the world,
especially in dry temperate and subtropical regions. Some
botanists have placed many of the genera into separate families,
such as the Agave Family (Agavaceae) and Amaryllis Family
(Amaryllidaceae). Although it is not as large as the Orchid
Family (Orchidaceae), the Lily Family has some spectacular
representatives with flowers that are as large and beautiful as
some orchids. Lilies are cultivated for their showy blossoms,
and some species are grown for food, alcoholic beverages and
strong leaf fibers. One of the most unusual uses for members of
this large plant family is soap. In fact, California has five
species and five varieties of true "soap lilies"
(Chlorogalum). Two of these species occur in the coastal sage scrub plant community adjacent to Palomar College. They were used extensively by
native Indian tribes and early settlers of this region. Several
other plant species in different and unrelated plant families
were also used for soap in other parts of the world.
Distribution
According to the Jepson Manual of Higher
Plants of California (1993), five species of soap lilies
(Chlorogalum) are native to California: C.
angustifolium, C. grandiflorum, C. purpureum,
C. parviflorum, and C. pomeridianum. According to
most ethnobotanical references on the early uses of California
plants, (C. parviflorum and C. pomeridianum) were
commonly used for food and soap by native Indians and early
settlers, especially the latter species. Both species occur in
the cismontane (coastal) mountains, valleys, and mesas of
southern California. Chlorogalum pomeridianum occupies
dry open hills and plains below 5,000 feet (1500 m), chiefly in the valley
grassland, coastal sage scrub, chaparral and foothill woodland
plant communities, from southern Oregon to San Diego County,
California. C. parviflorum occurs in dry open places below
2,000 feet (600 m), chiefly in the valley grassland and coastal sage scrub
plant communities from Los Angeles County to Riverside and San
Diego Counties and northern Baja California. C.
parviflorum often grows on dry, barren ridges or bluffs
within coastal sage scrub, while C. pomeridianum typically
grows in valley grassland and more sheltered (shady) sites in the
coastal sage scrub and chaparral.
Two distinct species of soap lilies in California: Chlorogalum pomeridianum (left) and C. parviflorum (right). C. pomeridianum has larger bulbs that are covered with long brown fibers.
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Chlorogalum purpureum var. reductum
A rare, purple-flowered species of soap lily native to the coastal ranges of Central California. Unlike the other white-flowered species of soap lilies native to California, this small, seldom-seen species has purple flowers. It grows in hard-packed, gravelly and pebbly soils in the La Panza Range of San Luis Obispo County. This is the only known location of this species in the wild. Another rare variety (var. purpureum) is only known from five locations near Jolon (Monterey County) on the Hunter Liggett Army Base, and at Camp Roberts in San Luis Obispo County.
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The rare Camatta Canyon amole (Chlorogalum purpureum var. reductum).
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Taxonomy
Soap lilies (Chlorogalum) are
acaulescent herbs with tufted basal leaves arising from a scaly
bulb that produces a tall, leafless paniculate inflorescence. The small
white flowers are often subtended by a scarious bract at the base
of each pedicel. Each flower consists of six perianth segments
composed of three outer sepals and three inner petals which are
very similar in size and shape. The perianth segments commonly
have a darkened midvein and become twisted together and
persistent above the developing fruit (capsule). The flowers also
consist of six stamens and a hypogynous ovary forming a
loculicidal 3-valved seed capsule. The following table shows the
main diagnostic taxonomic differences between C.
pomeridianum and C. parviflorum:
C.
pomeridianum |
C.
parviflorum
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Bulbs 7-15 cm long; heavily coated with dark brown
fibers. |
Bulbs 4-7 cm long, covered with brown membranous
coat. |
Leaves 20-70 cm long and 6-25 mm wide; very wavy
(undulate). |
Leaves 10-20 cm long and 3-9 mm wide; leaf margin
undulate. |
Flower stalk 60-250 cm tall. |
Flower stalk 30-90 cm tall. |
Perianth segments 15-23 mm long. |
Perianth segments 6-8 mm long. |
Flowers vespertine (nocturnal). |
Flowers diurnal. |
Although the flowers and bulbs of C.
pomeridianum are larger than those of C. parviflorum,
what really sets these two species apart are the unmistakable
bulb coats. Bulbs of C. pomeridianum are covered with
long, brown fibers, while those of C. parviflorum have a
brown, membranous coat. Although both species bloom during the
late spring and summer months, the flowers of
C. pomeridianum open at night, while those of C. parviflorum open during the daylight hours. In addition, the
leaves of C. pomeridianum are longer and wider.
The flowers of Chlorogalum pomeridianum are seldom observed in full bloom because they open at dusk. They are undoubtedly pollinated by night-flying insects such as small moths.
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Soap lily (Chlorogalum pomeridianum) in Kern County, California.
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The flowers of Chlorogalum parviflorum open during the daylight hours. As the specific epithet "parviflorum" implies, they are smaller than the other common soap lily (C. pomeridianum).
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Soap lily (Chlorogalum parviflorum) in San Diego County, California.
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The only other lily within the range of soap lilies that might be confused with Chlorogalum is the star lily Zigadenus. Star
lilies (Zigadenus fremontii) commonly grow in the sage scrub and grasslands of coastal mesas where soap lilies thrive. These two genera should not be
confused because some species of Zigadenus (also called
death camas) are quite poisonous to cattle, sheep, and humans if
ingested (Fuller and McClintock, 1986). The bulbs contain
zygadenine, a very toxic steroidal alkaloid. In fact,
Zigadenus was one of the few genera in which bulbs were
not eaten by native Indians (Balls, 1970). According to
Fuller and McClintock (1986), one or two pounds of death camas
may kill a 100 pound sheep. Bulbs of death camas made into flour
caused serious illness to members of the Lewis and Clark
expedition. Although its native range is quite different, the
desert lily (Hesperocallis undulata) has basal undulate
(wavy) leaves which are remarkably similar to those of
Chlorogalum. Unlike the poisonous Zigadenus, the
bulbs of both Chlorogalum and Hesperocallis were
used for food by the native Indian tribes of southern
California.
The range of this star lily (Zigadenus fremontii var. minor) coincides with both species of soap lilies in coastal California. Star lily bulbs contain a very poisonous alkaloid called zygadenine.
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Chemistry
Saponins are a group of glucosides found in
several plant species and are characterized by their soap-like
property of foaming in a water solution. Glucosides (or
glycosides) are plant compounds containing glucose (or another
sugar) combined with other non-sugar molecules. Upon hydrolysis
saponin glycosides yield a triterpenoid or steroid sapogenin and
one or more sugars, such as glucose, galactose, or xylose (Bonner
and Varner, 1965). Saponins lower the surface tension of aqueous
solutions and form colloidal dispersions in water. When shaken
they produce a nonalkaline soap-like froth. The amount of foam
produced is a rough indication of the amount of saponins present
in the solution.
Saponin in powder form has as its active
ingredient the triterpenoid component which is used chiefly as a
foaming and emulsifying agent. Triterpenoid saponins have been
used in the manufacture of foam fire extinguishers, toothpaste,
foam in beverages (including soft drinks and beer), shampoos,
liquid soaps, and cosmetic preparations. Steroidal sapogenins are
of interest because of the possibility of using them as a starting
material (precursor) for the synthesis of certain steroidal
hormones (Miller, 1957).
Unlike the cardiac glucosides, saponins do
not affect the heart. Saponins are especially
toxic to fish, and thus have attained a wide use as
fish poisons (Kirk, 1954). The toxin acts on the respiratory
organs of fish without affecting their edibility. Saponins also
result in the break down (hemolysis) of red blood cells
(erythrocytes) and may be fatal when solutions are injected into
the bloodstream of animals (Miller, 1957).
According to Muenscher (1961), several types of
glucosides yielding toxic products upon hydrolysis occur in
widely unrelated families. The most important groups of
glucosides concerned in plant poisoning are cyanogenetic
glucosides, saponin glucosides, solanines, and mustard oil
glucosides. Saponins are found in a number of plants considered
poisonous to livestock and humans if ingested. The degree or
severity of poisoning may be due to the type or amount of saponin
ingested or the particular products of hydrolysis.
As mentioned previously, several plants in
addition to Chlorogalum contain saponins and some are
economically important. These include the soapbark tree
(Quillaja saponaria), soapwort (Saponaria
officinalis), and the soapberry (Sapindus saponaria). Due
to the toxic nature of saponins and their hemolysis of red blood
cells, its use to increase the foaming power of beer and other
beverages has been discouraged (Hill, 1952).
An aqueous solution of soapberry fruits that has been vigorously shaken. The foaming action is caused by saponins present in the leathery fruit walls (pericarp). The three shiny round structures (lower left) are soapberry seeds, known in Central America as "black pearls."
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The soapberry tree is native to southern
Arizona, New Mexico and Texas, extending south through Mexico,
Central and South America. The leathery brown berries are rich
in saponins, glycosides containing glucose or a related sugar
plus a toxic triterpenoid component. They have the property of
foaming with water and have been used as soap in Mexico and
tropical America. In addition, saponins are especially toxic to
cold-blooded vertebrates, and crushed soapberry fruits were
thrown into ponds and streams to stupefy the fish so that they
would float to the surface to be gathered. Perhaps the most
fascinating part of the fruits are the black, marble-like seeds.
Known as "black pearls" throughout the American tropics, the
shiny seeds are used extensively in necklaces, bracelets and
earrings.
The shiny black seeds, leathery one-seeded fruits and mature leaf of the soapberry tree (Sapindus saponaria). The hard seeds are known as "black pearls" and are strung into bracelets and necklaces in Central America.
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A soapberry seed necklace (Sapindus saponaria) from the Hawaiian Islands. This widespread species of tree occurs in the southwestern United States, Mexico and South America, west across the Pacific Basin on a number of islands to New Caledonia. On the island of Hawaii it grows in mesic forests on Hualalai, Mauna Loa and Kilauea. It also occurs in Africa where the seeds are used in the board game called mancala.
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Ethnobotany
The amole or soap plant
(Chlorogalum pomeridianum) was widely used by native Indian tribes
of southern California, including the Diegueno, Luiseno, and
the Cahuilla. One important use of this plant is depicted by its common name of soap plant or soap lily. The outer scales and fibers were removed from the bulbs. Crushed bulbs rubbed on the hands or clothing produced a lather when rubbed vigorously with water. Bulbs were considered to be an
excellent shampoo, leaving the hair soft and glossy, and were
said to be useful in removing dandruff (Balls, 1970). A Palomar
College general biology student reported a slight problem with
pieces of the bulb scales in her hair after shampooing with a
local soap lily. This problem may have been the result of her
technique. The bulbs contain a saponin which is also found in
the soapberry tree (Sapindus). The lather does not contain
alkali and is especially good for washing delicate fabrics.
The bulbs of soap lilies were also used for
food. They were roasted with fibers and scales in place, then
peeled and eaten, or peeled and boiled prior to eating. The bulbs
were baked in stone-lined pits. Bulbs put into the oven at night
were ready by the following morning. The "earth ovens" consisted
of a pit dug into the ground, lined with rocks, and heated by
building a fire in it. When the rock lining was thoroughly
heated, the fire was raked out and the bulbs were placed in the
hot pit, covered with leaves, and then banked over with earth and
sometimes more rock. According to Balls (1970), the leaves of
poison oak (Rhus diversiloba) were used by the Karok
Indians of northwestern California to cover the bulbs while
baking them in the earth ovens. The slow cooking destroyed the
soapy nature of the bulbs leaving a good nourishing food. The course fibers covering the bulbs were used in making brushes for sweeping the
fine flour out of the inside of the basket-hopper used in the process
of grinding acorn flour. The fibers of C. pomeridianum were also used for sweeping out the bed rock mortars and baskets by the Cahuilla Indians (Bean and Saubel, 1972).
According to Balls (1970), the young spring
shoots of soap lilies were very sweet when cooked by the slow
process of the pit oven. While still young, the fresh green
leaves were also eaten raw. Older leaves were largely used for
wrapping acorn bread during baking. Medicinally, the roasted
bulbs were used as poultices for sores, and the fresh crushed
bulb was rubbed on the body to cure rheumatic pains and cramps.
The thick mucilaginous sap that oozed out of the baking bulbs was used as a glue for attaching feathers to arrow shafts and was smeared over
the wood of a new bow to take a covering of soot to make the new
bow look old (Balls, 1970). It was also smeared on baskets to make them watertight. In addition, the juice from the leaves was also
pricked into the skin to make green tattoo markings.
Wavy (undulate) leaves of a soap lily (Chlorogalum pomeridianum var. minus) in coastal central California. The shiny green rock is serpentine, an interesting formation in California associated with endemic plant species.
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The crushed green plant, including the bulb, was used in streams to stupefy fish (Kirk, 1970). Large
numbers of fish were caught by throwing the crushed or powderd bulbs into
carefully dammed streams. As the fish floated to the surface they
were picked out by hand or with a coarse-meshed net. This
cooperative fishing, where the whole village worked together,
meant that great quantities of bulbs would be prepared at one
time. According to Balls (1970), all the fish including eels
(not frogs) were stupefied. Apparently the harvesting of fish in
this manner had no ill effects on those who ate the fish. The fish were washed to remove any traces of the crushed bulbs from their gills. Other
plants have been used to stupefy fish in California but none so
widespread as Chlorogalum. This method of catching fish
has been employed by natives in other parts of the world. It is
illegal in California today because it wipes out fish of all age
groups--thus rapidly depleting the vital populations of fish in
streams and lakes.
Several other plants that occur in the same
general range as Chlorogalum were used in similar ways.
The entire foliage and roots of dove weed or turkey mullein
(Eremocarpus setigerus) were crushed and thrown into
streams to stupefy the fish. The large perennial taproots of
goosefoot or pigweed (Chenopodium californicum) were used
for soap. In fact, the ground up roots were used in the same way
as modern soap powder. Both of these species are common in the
coastal sage scrub plant community north of Palomar College.
The perennial taproot of the native goosefoot (Chenopodium californicum) contains saponins and was used for soap by early California settlers.
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Summary And Conclusions
Soap lilies (Chlorogalum) were widely used and extremely important plants to Indian tribes of southern California as well
as other parts of the state. This includes the Luiseno and
Diegueno Indians of the coastal regions of San Diego County; and
the Cahuilla Indians of the inland valleys and desert regions. The bulbs were used for food, soap, glue, fish poison, and brushes. According to Munz (1961),
the bulbs contain an abundance of starch and are an
excellent source of carbohydrates. Other parts of the plant, such
as leaves and stems, were eaten or used as a green die in tattoos.
Most authors cited in this article refer to the species C.
pomeridianum which has a much wider range, extending from
southern Oregon to southern California. However, in the dry
coastal mesas of San Diego County and Baja California, C.
parviflora appears to be locally more common and abundant.
Since the flowers of C. pomeridianum are nocturnal and
relatively short-lived, the nature of the bulb is an excellent
means of identification when inflorescences are not available
during much of the year.
One final point of interest is how native
people dug up the bulbs of soap lilies. The bulbs may be 15-20
centimeters deep and are extremely difficult to dig out of hard,
compact sandstone or decomposed granite--even with a full-sized
shovel. Considering all the uses made from this plant, the bulbs must have
been dug up in quantity. Perhaps the Indians dug out the bulbs
following rainy seasons in the spring while the ground was still
moist. According to Munz (1961), the long narrow leaves appear
after the first autumn rains and remain for many months. So bulbs
could be found throughout much of the year even when flower
stalks were not visible.
References
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- Balls, E.K. 1970. Early Uses of California Plants. University of California Press, Berkeley.
- Bean, L.J. and K.S. Saubel. 1972. Temalpakh: Cahuilla Indian Knowledge and Usage of Plants. Malki Museum Press, Banning, California.
- Bonner, J. and J.E. Varner. 1965. Plant Biochemistry. Academic Press, New York.
- Fuller, T.C. and E. McClintock. 1986. Poisonous Plants of California. University of California Press, Berkeley.
- Hickman, J.C. (Editor). 1993. The Jepson Manual of Higher Plants of California
. University of California Press, Berkeley.
- Higgins, E.B. 1949. Annotated Distributional List of the Ferns and Flowering Plants of San Diego County, California. Occasional Papers No. 8. San Diego Society of Natural History, San Diego, California.
- Hill, A.F. 1952. Economic Botany. McGraw-Hill Book Company, New York.
- Jepson, W.L. 1925. A Manual of the Flowering Plants of California. University of California Press, Berkeley.
- Kirk, D.R. 1970. Wild Edible Plants of the Western United States. Naturegraph Publishers, Healdsburg, California.
- Kirk, R.E. and D.F. Othmer. 1954. Encyclopedia of Chemical Technology. Vol. 12. The Interscience Encyclopedia, Inc., New York.
- Miller, E.V. 1957. The Chemistry of Plants. Reinhold Publishing Corp., New York.
- Muenscher, W.C. 1961. Poisonous Plants of the United States. The Macmillan Company, New York.
- Munz, P.A. and D.D. Keck. 1959. A California Flora. University of California Press, Berkeley.
- Munz, P.A. 1961. California Spring Wildflowers. University of California Press, Berkeley.
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