Salsola soda
Encyclopedia
Salsola soda, more commonly known in English as Opposite Leaved Saltwort
, Oppositeleaf Russian Thistle, or Barilla Plant, is a small (to 0.7 m tall), annual, succulent shrub that is native to the Mediterranean Basin
. It is a halophyte
(a salt-tolerant plant) that typically grows in coastal regions and can be irrigated with salt water.
The plant has great historical importance as a source of soda ash, which was extracted from the ashes of Salsola soda and other saltwort
plants. Soda ash is one of the alkali
substances that are crucial in glassmaking and soapmaking. The famed clarity of 16th century cristallo glass
from Murano and Venice
depended upon the purity of "Levant
ine soda ash," and the nature of this ingredient was kept secret. Spain had an enormous 18th century industry that produced soda ash from the saltworts (barrilla in Spanish). Soda ash is now known to be predominantly sodium carbonate
. In 1807, Sir Humphry Davy
isolated a metallic element from caustic soda; he named the new element "sodium
" to indicate its relationship to "soda." Before soda was synonymous (in U.S. English) with soft drinks, the word referred to Salsola soda and other saltwort
plants, and to "sodas" derived from soda ash.
While the era of farming for soda ash is long past, Salsola soda is still cultivated as a vegetable that enjoys considerable popularity in Italy and with gourmets around the world. Its common names in Italian include Barba di Frate, Agretti, and Liscari sativa (short: Lischi or Lischeri). Of its culinary value, Frances Mayes
has written that "Spinach is the closest taste, but while agretti has the mineral sharpness of spinach, it tastes livelier, full of the energy of spring."
s that grow out of the base of the leaves near the stem.
It has become naturalized along the Pacific coast of North America,
and there is concern about its invasiveness
in California's salt marshes. It is also reported to be naturalized in South America.
materials essential to making soda-lime glass
, soap
, and many other products. The principal active ingredient is sodium carbonate
, with which the term "soda ash" is now nearly synonymous. The processed ashes of Salsola soda contain as much as 30% sodium carbonate.
A high concentration of sodium carbonate in the ashes of Salsola soda occurs if the plant is grown in highly saline soils (i.e. in soils with a high concentration of sodium chloride), so that the plant's tissues contain a fairly high concentration of sodium ions. Salsola soda can be irrigated with sea water, which contains about 40 grams per liter of dissolved sodium chloride and other salts. When these sodium-rich plants are burned, the carbon dioxide that is produced presumably reacts with this sodium to form sodium carbonate.
It is surprising to find a higher concentration of sodium than of potassium in plant tissues; the former element is usually toxic, and the latter element is essential, to the metabolic processes of plants. Thus most plants, and especially most crop plants, are "glycophytes", and suffer damage when planted in saline soils. Salsola soda, and the other plants that were cultivated for soda ash, are "halophytes" that tolerate much more saline soils than do glycophytes, and that can thrive with much larger densities of sodium in their tissues than can glycophytes.
The biochemical processes within the cells of halophytes are typically as sensitive to sodium as are the processes in glycophytes. Sodium ions from a plant's soil or irrigation water are toxic primarily because they interfere with biochemical processes within a plant's cells that require potassium
, which is a chemically similar alkali metal
element. The cell of a halophyte
such as Salsola soda has a molecular transport mechanism that sequesters sodium ions into a compartment within the plant cell
called a "vacuole." The vacuole of a plant cell can occupy 80% of the cell's volume; most of a halophyte plant cell's sodium can be sequestered in the vacuole, leaving the rest of the cell with a tolerable ratio of sodium to potassium ions.
In addition to Salsola soda, soda ash has also been produced from the ashes of Salsola kali
(another saltwort
plant), of glasswort
plants, and of kelp
, a type of seaweed. The sodium carbonate, which is water soluble, is "lixiviated" from the ashes (extracted with water), and the resulting solution is boiled dry to obtain the finished soda ash product. A very similar process is used to obtain potash
(mainly potassium carbonate
) from the ashes of hardwood trees. Because halophytes must also have potassium ions in their tissues, even the best soda ash derived from them also contains some potash (potassium carbonate), as was known by the 19th century.
Plants were a very important source of soda ash until the early 19th century. In the 18th century, Spain
had an enormous industry producing "barilla
" (one type of plant-derived soda ash) from saltwort plants (barrilla in Spanish). Similarly, Scotland
had a large 18th century industry producing soda ash from kelp; this industry was so lucrative that it led to overpopulation in the Western Isles of Scotland, and one estimate is that 100,000 people were occupied with "kelping" during the summer months. The commercialization of the Leblanc process
for synthesizing sodium carbonate (from salt, limestone
, and sulfuric acid
) brought an end to the era of farming for soda ash in the first half of the 19th century.
at about 30% to 40% standard, much like Rosemary
. Though the plant is often grown in saltwater irrigated land in the Mediterranean Basin
, it will grow without salt water. Salsola soda is harvested in bunches when small, or cropped regularly to encourage new growth when mature. It is most commonly boiled and eaten as a leafy vegetable; the recommendation is to cook it in boiling water until the leaves soften, and to serve while some bite (crunch) remains (much like Samphire). It can also be eaten raw; it is said to "taste grassy and slightly salty with a pleasant crunchy texture."
Salsola soda is sometimes confused with a plant known in Japan as Okahijiki ("Land Seaweed"), which is actually the species Salsola komarovi. The harvested leaves of the two species have a similar appearance.
"biodesalinating companion plant" for crops such as tomatoes and peppers when they are grown in saline soils. The Salsola soda extracts enough sodium from the soil to improve the growth of the crop plant, and better crop yields result despite the competition of the two plants for the remaining minerals from the soil.
Salsola
Salsola is a genus of the subfamily Salsoloideae in the family Amaranthaceae. A common name of various members of this genus is saltwort, for its salt tolerance.-Description:...
, Oppositeleaf Russian Thistle, or Barilla Plant, is a small (to 0.7 m tall), annual, succulent shrub that is native to the Mediterranean Basin
Mediterranean Basin
In biogeography, the Mediterranean Basin refers to the lands around the Mediterranean Sea that have a Mediterranean climate, with mild, rainy winters and hot, dry summers, which supports characteristic Mediterranean forests, woodlands, and scrub vegetation...
. It is a halophyte
Halophyte
A halophyte is a plant that grows where it is affected by salinity in the root area or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. An example of a halophyte is the salt marsh grass Spartina alterniflora . Relatively few plant species are...
(a salt-tolerant plant) that typically grows in coastal regions and can be irrigated with salt water.
The plant has great historical importance as a source of soda ash, which was extracted from the ashes of Salsola soda and other saltwort
Saltwort
Saltwort is a common name for several genera of flowering plants, including:*Batis, family Bataceae*Salicornia and Salsola, family Amaranthaceae*Salsola kali, prickly saltwort...
plants. Soda ash is one of the alkali
Alkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
substances that are crucial in glassmaking and soapmaking. The famed clarity of 16th century cristallo glass
Cristallo
Cristallo is a glass which is totally clear , without the slight yellow or greenish color originating from iron oxide impurities. This effect is achieved through small additions of manganese oxide...
from Murano and Venice
Venetian glass
Venetian glass is a type of glass object made in Venice, Italy, primarily on the island of Murano. It is world-renowned for being colourful, elaborate, and skillfully made....
depended upon the purity of "Levant
Levant
The Levant or ) is the geographic region and culture zone of the "eastern Mediterranean littoral between Anatolia and Egypt" . The Levant includes most of modern Lebanon, Syria, Jordan, Israel, the Palestinian territories, and sometimes parts of Turkey and Iraq, and corresponds roughly to the...
ine soda ash," and the nature of this ingredient was kept secret. Spain had an enormous 18th century industry that produced soda ash from the saltworts (barrilla in Spanish). Soda ash is now known to be predominantly sodium carbonate
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...
. In 1807, Sir Humphry Davy
Humphry Davy
Sir Humphry Davy, 1st Baronet FRS MRIA was a British chemist and inventor. He is probably best remembered today for his discoveries of several alkali and alkaline earth metals, as well as contributions to the discoveries of the elemental nature of chlorine and iodine...
isolated a metallic element from caustic soda; he named the new element "sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
" to indicate its relationship to "soda." Before soda was synonymous (in U.S. English) with soft drinks, the word referred to Salsola soda and other saltwort
Saltwort
Saltwort is a common name for several genera of flowering plants, including:*Batis, family Bataceae*Salicornia and Salsola, family Amaranthaceae*Salsola kali, prickly saltwort...
plants, and to "sodas" derived from soda ash.
While the era of farming for soda ash is long past, Salsola soda is still cultivated as a vegetable that enjoys considerable popularity in Italy and with gourmets around the world. Its common names in Italian include Barba di Frate, Agretti, and Liscari sativa (short: Lischi or Lischeri). Of its culinary value, Frances Mayes
Frances Mayes
Frances Mayes is an American university professor, poet, memoirist, essayist, and novelist.Born and raised in Fitzgerald, Georgia, Mayes attended Randolph-Macon Woman's College in Lynchburg, Virginia, and obtained her BA from the University of Florida...
has written that "Spinach is the closest taste, but while agretti has the mineral sharpness of spinach, it tastes livelier, full of the energy of spring."
Description
This annual, succulent plant can grow into small shrubs up to 0.7 meters tall (sometimes called sub-shrubs). It has fleshy green leaves with either green or red stems. The tiny flowers develop from inflorescenceInflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
s that grow out of the base of the leaves near the stem.
Distribution
Salsola soda is native in Eurasia and North Africa. Historically, it was well known in Italy, Sicily, and Spain. In modern Europe, it is also found on the Atlantic coasts of France and Portugal and on the Black Sea coast.It has become naturalized along the Pacific coast of North America,
and there is concern about its invasiveness
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
in California's salt marshes. It is also reported to be naturalized in South America.
Soda ash and the biology of sodium accumulation
The ashes obtained by the burning of Salsola soda can be refined to make a product called soda ash, which is one of the alkaliAlkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
materials essential to making soda-lime glass
Soda-lime glass
Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of glass, used for windowpanes, and glass containers for beverages, food, and some commodity items...
, soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
, and many other products. The principal active ingredient is sodium carbonate
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...
, with which the term "soda ash" is now nearly synonymous. The processed ashes of Salsola soda contain as much as 30% sodium carbonate.
A high concentration of sodium carbonate in the ashes of Salsola soda occurs if the plant is grown in highly saline soils (i.e. in soils with a high concentration of sodium chloride), so that the plant's tissues contain a fairly high concentration of sodium ions. Salsola soda can be irrigated with sea water, which contains about 40 grams per liter of dissolved sodium chloride and other salts. When these sodium-rich plants are burned, the carbon dioxide that is produced presumably reacts with this sodium to form sodium carbonate.
The biochemical processes within the cells of halophytes are typically as sensitive to sodium as are the processes in glycophytes. Sodium ions from a plant's soil or irrigation water are toxic primarily because they interfere with biochemical processes within a plant's cells that require potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
, which is a chemically similar alkali metal
Alkali metal
The alkali metals are a series of chemical elements in the periodic table. In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements, along with hydrogen. The alkali metals are lithium , sodium , potassium , rubidium , caesium , and francium...
element. The cell of a halophyte
Halophyte
A halophyte is a plant that grows where it is affected by salinity in the root area or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. An example of a halophyte is the salt marsh grass Spartina alterniflora . Relatively few plant species are...
such as Salsola soda has a molecular transport mechanism that sequesters sodium ions into a compartment within the plant cell
Plant cell
Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. Their distinctive features include:...
called a "vacuole." The vacuole of a plant cell can occupy 80% of the cell's volume; most of a halophyte plant cell's sodium can be sequestered in the vacuole, leaving the rest of the cell with a tolerable ratio of sodium to potassium ions.
In addition to Salsola soda, soda ash has also been produced from the ashes of Salsola kali
Salsola kali
Kali soda is an annual plant that grows in arid soils and in sandy coastal soils. Its original range is Eurasian, but it has become naturalized, and even invasive, in North America, Australia, and elsewhere...
(another saltwort
Saltwort
Saltwort is a common name for several genera of flowering plants, including:*Batis, family Bataceae*Salicornia and Salsola, family Amaranthaceae*Salsola kali, prickly saltwort...
plant), of glasswort
Glasswort
Salicornia is a genus of succulent, halophyte plants that grow in salt marshes, on beaches, and among mangroves. Salicornia species are native to North America, Europe, South Africa, and South Asia...
plants, and of kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
, a type of seaweed. The sodium carbonate, which is water soluble, is "lixiviated" from the ashes (extracted with water), and the resulting solution is boiled dry to obtain the finished soda ash product. A very similar process is used to obtain potash
Potash
Potash is the common name for various mined and manufactured salts that contain potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains, and this was the major historical source for it before the industrial era...
(mainly potassium carbonate
Potassium carbonate
Potassium carbonate is a white salt, soluble in water , which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid...
) from the ashes of hardwood trees. Because halophytes must also have potassium ions in their tissues, even the best soda ash derived from them also contains some potash (potassium carbonate), as was known by the 19th century.
Plants were a very important source of soda ash until the early 19th century. In the 18th century, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
had an enormous industry producing "barilla
Barilla
Barilla S.p.A. is a major Italian and European food company founded in 1877 in Parma, Italy by Pietro Barilla...
" (one type of plant-derived soda ash) from saltwort plants (barrilla in Spanish). Similarly, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
had a large 18th century industry producing soda ash from kelp; this industry was so lucrative that it led to overpopulation in the Western Isles of Scotland, and one estimate is that 100,000 people were occupied with "kelping" during the summer months. The commercialization of the Leblanc process
Leblanc process
The Leblanc process was the industrial process for the production of soda ash used throughout the 19th century, named after its inventor, Nicolas Leblanc. It involved two stages: Production of sodium sulfate from sodium chloride, followed by reaction of the sodium sulfate with coal and calcium...
for synthesizing sodium carbonate (from salt, limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
, and sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
) brought an end to the era of farming for soda ash in the first half of the 19th century.
Cultivation and culinary uses
The Italian name agretti is commonly used in English to refer to the edible leaves of Salsola soda; Barba Di Frate (or Friar's Beard) is the most common of the Italian names. This plant is not a summer green and should be started early indoors or in Autumn. The seed is notorious for poor germinationGermination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
at about 30% to 40% standard, much like Rosemary
Rosemary
Rosemary, , is a woody, perennial herb with fragrant, evergreen, needle-like leaves and white, pink, purple or blue flowers, native to the Mediterranean region. It is a member of the mint family Lamiaceae, which includes many other herbs, and is one of two species in the genus Rosmarinus...
. Though the plant is often grown in saltwater irrigated land in the Mediterranean Basin
Mediterranean Basin
In biogeography, the Mediterranean Basin refers to the lands around the Mediterranean Sea that have a Mediterranean climate, with mild, rainy winters and hot, dry summers, which supports characteristic Mediterranean forests, woodlands, and scrub vegetation...
, it will grow without salt water. Salsola soda is harvested in bunches when small, or cropped regularly to encourage new growth when mature. It is most commonly boiled and eaten as a leafy vegetable; the recommendation is to cook it in boiling water until the leaves soften, and to serve while some bite (crunch) remains (much like Samphire). It can also be eaten raw; it is said to "taste grassy and slightly salty with a pleasant crunchy texture."
Salsola soda is sometimes confused with a plant known in Japan as Okahijiki ("Land Seaweed"), which is actually the species Salsola komarovi. The harvested leaves of the two species have a similar appearance.
Phytoremediation
Salsola soda has also been studied as a bioremediationBioremediation
Bioremediation is the use of microorganism metabolism to remove pollutants. Technologies can be generally classified as in situ or ex situ. In situ bioremediation involves treating the contaminated material at the site, while ex situ involves the removal of the contaminated material to be treated...
"biodesalinating companion plant" for crops such as tomatoes and peppers when they are grown in saline soils. The Salsola soda extracts enough sodium from the soil to improve the growth of the crop plant, and better crop yields result despite the competition of the two plants for the remaining minerals from the soil.
External links
- "PLANTS Profile for Salsola soda." Natural Resources Conservation Service, United State Department of Agriculture. Retrieved November 3, 2006.
- Excellent gallery of photographs of Salsola soda (soude commune) from Bouches du Rhône region of France. From Banque de données Botaniques et Ecologiques, Universite Aix-Marseille, France. Retrieved November 30, 2006.
- Salsola soda listing at website Plants for a Future (http://www.pfaf.org). Retrieved December 7, 2006.