Phytolith
Encyclopedia
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
, "plant stone"), which are rigid, microscopic structures of varying sizes and shapes. Although some use "phytolith" to refer to all mineral secretions by plants, it more commonly refers to siliceous plant remains. Mineralized calcium secretions, commonly used for diagnostic research in cacti
Cacti
-See also:* RRDtool The underlying software upon which Cacti is built* MRTG The original Multi Router Traffic Grapher from which RRDtool was "extracted".* Munin -External links:******...
remains, are composed of calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...
s.
History of Phytolith Research
According to Dolores PipernoDolores Piperno
Dolores Piperno is an American archaeologist specializing in archaeobotany. She is a staff scientist emeritus of the Smithsonian Tropical Research Institute in Balboa, Panama.-Career:...
, an expert in the field of phytolith analysis, there have been four important stages of phytolith research throughout history.
- Discovery and Exploratory Stage (1835–1895): The first report on phytoliths was published by a German botanist named Struve in 1835. During this time another German scientist named Christian Gottfried EhrenbergChristian Gottfried EhrenbergChristian Gottfried Ehrenberg , German naturalist, zoologist, comparative anatomist, geologist, and microscopist, was one of the most famous and productive scientists of his time.- Early collections :...
was one of the leaders in the field of phytolith analysis. He developed the first classification system for phytoliths, and analyzed soil samples that were sent to him from all around the world. Most notably, Ehrenberg recorded phytoliths in samples he received from the famous naturalist, Charles DarwinCharles DarwinCharles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
, who had collected the dust from the sails of his ship, the HMS Beagle, off the coast of the Cape Verde Islands. - Botanical Phase of Research (1895–1936): Phytolith structures in plants gained wide recognition and attention throughout Europe. Research on production, taxonomy and morphology exploded. Detailed notes and drawings on plant families that produce silica structures and morphology within families were published.
- Period of Ecological Research (1955–1975): First applications of phytolith analysis to paleoecological work, mostly in Australia, the United States, the United Kingdom, and Russia. Classification systems for differentiation within plant families became popular.
- Modern Period of Archaeological and Paleoenvironmental Research (1978–Present): Archaeobotanists working in the Americas first consider and analyze phytolith assemblages in order to track prehistoric plant use and domestication. Also for the first time, phytolith data from pottery are used to track history of clay procurement and pottery manufacture. Around the same time, phytolith data are also used as a means of vegetation reconstruction among paleoecologists. A much larger reference collection on phytolith morphology within varying plant families is assembled.
Development in Plants
First, soluble silica, also called monosilicic acid, is taken up from the soil when plant roots absorb groundwater. From there, it is carried to other plant organs by the xylemXylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...
. By an unknown mechanism, which appears to be linked to genetics and metabolism, some of the silica is then laid down in the plant as silicon dioxide. This biological mechanism does not appear to be limited to specific plant structures, as some plants have been found with silica in their reproductive and sub-surface organs.
Chemical and Physical Characteristics
Phytoliths are composed mainly of noncrystalline silicon dioxide, and are about 4% to 9% water. Research has also established that less than 1% to 5% of each phytolith's weight is composed of carbon, nitrogen, and other trace elements. These elements are all present in the cells of plants before they are filled with silica deposits, so they are retained in the phytoliths. Because carbon is preserved in phytoliths, radiocarbon dating techniques are ideal for use in reconstructing past vegetation.The silica in phytoliths has a refractive index
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
ranging from 1.41 to 1.47, and a specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
from 1.5 to 2.3. Phytoliths may be colorless, light brown, or opaque; most are transparent. Phytoliths exist in various three-dimensional shapes, some of which are specific to plant families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
, genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
or species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
.
Function
There is still debate in the scientific community as to why plants form phytoliths, and whether silica should be considered an essential nutrient for plants. Studies that have grown plants in silica-free environments have typically found that plants lacking silica in the environment do not grow as well. For example, the stems of certain plants will collapse when grown in soil lacking silica. In many cases, phytoliths appear to lend structure and support to the plant, much like the spiculesSponge spicule
Spicules are structural elements found in most sponges. They provide structural support and deter predators. Large spicules, visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres.- Structure :...
in sponges and leather corals
Alcyonacea
The Alcyonacea, or the soft corals are an order of corals which do not produce calcium carbonate skeletons. Soft corals contain minute, spiny skeletal elements called sclerites. Aside from their scientific utility in species identification, sclerites give these corals some degree of support and...
. Phytoliths may also provide plants with protection. These rigid silica structures help to make plants more difficult to consume and digest, lending the plant's tissues a grainy or prickly texture. Phytoliths also appear to provide physiologic benefits. Experimental studies have shown that the silicon dioxide in phytoliths may help to alleviate the damaging effects of toxic heavy metals, such as aluminum.
Finally, calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...
s serve as a reserve of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
. Cacti
Cacti
-See also:* RRDtool The underlying software upon which Cacti is built* MRTG The original Multi Router Traffic Grapher from which RRDtool was "extracted".* Munin -External links:******...
use these as a reserve for photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
during the day when they close their pores to avoid water loss; baobabs use this property to make their trunks more flame-resistant.
Patterns of Phytolith Production
Because identification of phytoliths is based on morphologyMorphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
, it is important to note taxonomical
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
differences in phytolith production.
Families with high phytolith production; family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
and genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
-specific phytolith morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
is common:
- AcanthaceaeAcanthaceaeThe family Acanthaceae is a taxon of dicotyledonous flowering plants containing almost 250 genera and about 2500 species....
, AceraceaeAceraceaeAceraceae is a family of flowering plants also called the Maple Family. It contains two to four genera, depending upon the circumscription, of some 120 species of trees and shrubs. A common characteristic is that the leaves are opposite, and the fruit a schizocarp.The maples have long been known...
, AnnonaceaeAnnonaceaeAnnonaceae, also called the custard apple familyis a family of flowering plants consisting of trees, shrubs or rarely lianas.With about 2300 to 2500 species and more than 130 genera,...
, ArecaceaeArecaceaeArecaceae or Palmae , are a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates...
, AsteraceaeAsteraceaeThe Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
, BoraginaceaeBoraginaceaeBoraginaceae, the Borage or Forget-me-not family, include a variety of shrubs, trees, and herbs, totaling about 2,000 species in 146 genera found worldwide.A number of familiar plants belong to this family....
, BromeliaceaeBromeliaceaeBromeliaceae is a family of monocot flowering plants of around 3,170 species native mainly to the tropical Americas, with a few species found in the American subtropics and one in tropical west Africa, Pitcairnia feliciana...
, BurseraceaeBurseraceaeBurseraceae is a moderate-sized family of 17-18 genera and about 540 species of flowering plants. The actual numbers differ according to the time period in which a given source is written describing this family. The Burseraceae is also known as the Torchwood family, the frankincense and myrrh...
, ChrysobalanaceaeChrysobalanaceaeChrysobalanaceae is a family of trees, shrubs and flowering plants, consisting of 17 genera and about 460 species of leptocaul that grows in the Tropics or is subtropical and common in the Americas...
, CommelinaceaeCommelinaceaeCommelinaceae is a family of flowering plants. In less formal contexts, the group is referred to as the dayflower family or spiderwort family. It is one of five families in the order Commelinales and by far the largest of these with an estimated 650 species in 40 genera. Well known genera include...
, CostaceaeCostaceaeCostaceae or the Costus Family is a family of pantropical monocots. They belong to the order Zingiberales, which contains other horticulturally and economically important plants such as the banana , bird-of-paradise , and edible ginger...
, Curcurbitaceae, CyatheaceaeCyatheaceaeThe Cyatheaceae is the scaly tree fern family and includes the world's tallest tree ferns, which reach heights up to 20 m. They are also very ancient plants, appearing in the fossil record in the late Jurassic, though the modern genera likely appeared in the Tertiary. Cyatheaceae is the largest...
, CyperaceaeCyperaceaeCyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
, DilleniaceaeDilleniaceaeDilleniaceae is the botanical name for a family of flowering plants. Such a family has been universally recognized by taxonomists. It is known to gardeners for the genus Hibbertia, which contains many commercially valuable garden species....
, EquisetaceaeEquisetaceaeEquisetaceae, sometimes called the horsetail family, is the only extant family of the class Equisetales, with one surviving genus, Equisetum, which comprises about twenty species.- Evolution and systematics :...
, Heliconiaceae, Hymenophyllaceae, MagnoliaceaeMagnoliaceaeThe Magnoliaceae, or Magnolia Family, is a flowering plant family in the order Magnoliales. It consists of two subfamilies:*Magnolioideae, of which Magnolia is the most well-known genus....
, MarantaceaeMarantaceaeThe Marantaceae or arrowroot family is a family of flowering plants known for its large starchy rhizomes. It is sometimes called the prayer-plant family...
, MoraceaeMoraceaeMoraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 40 genera and over 1000 species. Most are widespread in tropical and subtropical regions, less so in temperate climates...
, MusaceaeMusaceaeMusaceae is a botanical name for a family of flowering plants. The family is native to the tropics of Africa and Asia. The plants have a large herbaceous growth habit with leaves with overlapping basal sheaths that form a pseudostem making some members appear to be woody trees.The family has been...
, OrchidaceaeOrchidaceaeThe Orchidaceae, commonly referred to as the orchid family, is a morphologically diverse and widespread family of monocots in the order Asparagales. Along with the Asteraceae, it is one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species,...
, PoaceaePoaceaeThe Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
, PodostemaceaePodostemaceaeThe Podostemaceae is a family in the order Malpighiales. It comprises about 50 genera and 250 species of more or less thalloid aquatic herbs....
, Selaginellaceae, UlmaceaeUlmaceaeUlmaceae is a family of flowering plant that includes the elms , and the zelkovas . Members of the family are widely distributed throughout the north temperate zone, and have a scattered distribution elsewhere except for Australasia.The family was formerly sometimes treated to include the...
, UrticaceaeUrticaceaeUrticaceae, or the nettle family, is a family of flowering plants. The family name comes from the genus Urtica . Urticaceae includes a number of well-known and useful plants, including the aforementioned nettles, Ramie , māmaki , and ajlai .The family includes approximately 2600 species, grouped...
, ZingiberaceaeZingiberaceaeZingiberaceae, or the Ginger family, is a family of flowering plants consisting of aromatic perennial herbs with creeping horizontal or tuberous rhizomes, comprising ca. 52 genera and more than 1300 species, distributed throughout tropical Africa, Asia, and the Americas.Many species are important...
Families where phytolith production may not be high; family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
and genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
-specific phytolith morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
is common:
- CapparaceaeCapparaceaeCapparaceae , commonly known as the Caper family, is a family of plants in order Brassicales. As currently circumscribed, it contains 33 genera and about 700 species...
, CupressaceaeCupressaceaeThe Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera , which include the junipers and redwoods, with about 130-140 species in total. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall...
, DipterocarpaceaeDipterocarpaceaeDipterocarpaceae is a family of 17 genera and approximately 500 species of mainly tropical lowland rainforest trees. The family name, from the type genus Dipterocarpus, is derived from Greek and refers to the two-winged fruit...
, EuphorbiaceaeEuphorbiaceaeEuphorbiaceae, the Spurge family are a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees. Some are succulent and resemble cacti....
, FagaceaeFagaceaeThe family Fagaceae, or beech family, comprises about 900 species of both evergreen and deciduous trees and shrubs, which are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like nuts. Fagaceous leaves are often...
, FlacourtiaceaeFlacourtiaceaeFlacourtiaceae is a defunct family of flowering plants whose former members have been scattered to various other families, mostly to Achariaceae, Samydaceae, and Salicaceae. It was so vaguely defined that hardly anything seemed out of place there and it became a dumping ground for odd and anomalous...
, FlagellariaceaeFlagellariaceaeFlagellariaceae is the botanical name for a family of flowering plants. Such a family has rarely been recognized by taxonomists.The APG II system, of 2003 , does recognize such a family, and assigns it to the order Poales in the clade commelinids, in the monocots...
, JoinvilleaceaeJoinvilleaceaeJoinvilleaceae is a family of flowering plants. The APG II system, of 2003 assigns it to the order Poales in the clade commelinids in the monocots. The family consists of one genus with four currently accepted species, distributed from the Malay Peninsula to the Caroline Islands and high islands...
, PinaceaePinaceaePinaceae are trees or shrubs, including many of the well-known conifers of commercial importance such as cedars, firs, hemlocks, larches, pines and spruces. The family is included in the order Pinales, formerly known as Coniferales. Pinaceae are supported as monophyletic by its protein-type sieve...
, PolypodiaceaePolypodiaceaePolypodiaceae is a family of polypod ferns, which includes more than 60 genera divided into several tribes and containing around 1,000 species. Nearly all are epiphytes, but some are terrestrial.-Description:...
, RestionaceaeRestionaceaeRestionaceae, also called restiads, is the botanical name for a family of rush-like flowering plants native to the Southern Hemisphere.- Description :...
, TaxaceaeTaxaceaeThe family Taxaceae, commonly called the yew family, includes three genera and about 7 to 12 species of coniferous plants, or in other interpretations , six genera and about 30 species....
, TaxodiaceaeTaxodiaceaeThe Taxodiaceae were at one time regarded as a distinct plant family comprising the following ten genera of coniferous trees:*Athrotaxis*Cryptomeria*Cunninghamia*†Cunninghamites*Glyptostrobus*Metasequoia*Sciadopitys...
Families where phytolith production is common; family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
and genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
-specific phytolith morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
is uncommon:
- AristolochiaceaeAristolochiaceaeThe Aristolochiaceae, or the Birthwort family, are a family of flowering plants with 7 genera and about 400 species belonging to the order Piperales...
, ChloranthaceaeChloranthaceaeChloranthaceae is the botanical name of a family of flowering plants. The family consists of four genera, totalling several dozen species, of herbaceous or woody plants occurring in Southeast Asia, the Pacific, Madagascar, Central & South America, and the West Indies...
, CombretaceaeCombretaceaeCombretaceae is a family of flowering plants in the order Myrtales. The family includes about 600 species of trees, shrubs, and lianas in 18 genera. The family includes the leadwood tree, Combretum imberbe. Three genera, Conocarpus, Laguncularia and Lumnitzera, grow in mangrove habitats ....
, HernandiaceaeHernandiaceaeHernandiaceae is the botanical name for a family of flowering plants. Such a family has been recognised by most taxonomists.The APG II system, of 2003 , also recognizes this family, and assigns it to the order Laurales in the clade magnoliids...
, LoranthaceaeLoranthaceaeLoranthaceae is a family of flowering plants, which has been universally recognized by taxonomists. It consists of about 75 genera and 1,000 species of woody plants, many of them hemi-parasites, all of them except three having the mistletoe habit...
, MenispermaceaeMenispermaceaeMenispermaceae, the botanical name for a family of flowering plants, has been universally recognized by taxonomists. Tubocurare, a neuromuscular blocker and active ingredient in curare, is derived from plants of this family....
, PiperaceaePiperaceaeThe Piperaceae, also known as the pepper family, is a large family of flowering plants. The group contains roughly 3,610 currently accepted species in five genera. The vast majority of peppers can be found within the two main genera: Piper and Peperomia .Members of the Piperaceae may be small...
, SapotaceaeSapotaceaeSapotaceae is a family of flowering plants, belonging to order Ericales. The family includes approximately 800 species of evergreen trees and shrubs in approximately 65 genera . Distribution is pantropical....
, VerbenaceaeVerbenaceaeVerbenaceae, commonly known as the verbena family or vervain family, is a family of mainly tropical flowering plants. It contains trees, shrubs and herbs notable for heads, spikes, or clusters of small flowers, many of which have an aromatic smell.Recent phylogenetic studies have shown that...
Families where phytolith productions varies; family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
and genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
-specific phytolith morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
is uncommon:
- ClusiaceaeClusiaceaeThe Clusiaceae or Guttiferae Juss. is a family of plants formerly including about 37 genera and 1610 species of trees and shrubs, often with milky sap and fruits or capsules for seeds. It is primarily tropical...
, FabaceaeFabaceaeThe Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
, MalvaceaeMalvaceaeMalvaceae, or the mallow family, is a family of flowering plants containing over 200 genera with close to 2,300 species. Judd & al. Well known members of this family include okra, jute and cacao...
, SterculiaceaeSterculiaceaeSterculiaceae is a botanical name for a group of flowering plants at the rank of family, which is now considered obsolete. As is true for any botanical name, the circumscription, status and placement of the taxon has varied with taxonomic point of view...
Families where phytolith production is rare or not observed:
- AgavaceaeAgavaceaeAgavoideae is a subfamily of monocot flowering plants in the family Asparagaceae, order Asparagales. It has previously been treated as a separate family, Agavaceae. The group includes many well-known desert and dry zone types such as the agave, yucca, and Joshua tree...
, AlismataceaeAlismataceaeThe water-plantains are a family of flowering plants, comprising 11 genera and between 85-95 species. The family has a cosmopolitan distribution, with the greatest number of species in temperate regions of the Northern Hemisphere...
, AmaranthaceaeAmaranthaceaeThe flowering plant family Amaranthaceae, the Amaranth family, contains about 176 genera and 2,400 species.- Description :Most of these species are herbs or subshrubs; very few are trees or climbers. Some species are succulent....
, AmaryllidaceaeAmaryllidaceaeAmaryllidoideae is the subfamily of flowering plants that takes its name from the genus Amaryllis. It is part of the family Amaryllidaceae, in order Asparagales...
, ApiaceaeApiaceaeThe Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
, ApocynaceaeApocynaceaeThe Apocynaceae or dogbane family is a family of flowering plants that includes trees, shrubs, herbs, and lianas.Many species are tall trees found in tropical rainforests, and most are from the tropics and subtropics, but some grow in tropical dry, xeric environments. There are also perennial herbs...
, AraceaeAraceaeAraceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe or leaf-like bract. Also known as the Arum family, members are often colloquially...
, AraliaceaeAraliaceaeAraliaceae is a family of flowering plants, also known as the Aralia family or Ivy family. The family includes 254 species of trees, shrubs, lianas and perennial herbaceous plants into 2 subfamilies...
, AraucariaceaeAraucariaceaeAraucariaceae, commonly referred to as araucarians, is a very ancient family of coniferous trees. It achieved its maximum diversity in the Jurassic and Cretaceous periods, when it was distributed almost worldwide...
, AsclepiadaceaeAsclepiadaceaeAccording to APG II, the Asclepiadaceae is a former plant family now treated as a subfamily in the Apocynaceae...
, BignoniaceaeBignoniaceaeThe Bignoniaceae, or Trumpet Creeper Family, is a family of flowering plants comprising about 650-750 species in 116-120 genera. Members of the family are mostly trees and lianas , shrubs and more rarely herbaceous plants. As climber plants, they are twine climbers or tendril climbers, and rarely...
, BixaceaeBixaceaeBixaceae, or the achiote family, is a family of dicotyledonous plants. Under the Cronquist system, it was traditionally placed in the order Violales...
, Bombacaeae, BurmanniaceaeBurmanniaceaeBurmanniaceae is a botanical name of a family of flowering plants, consisting of about a hundred species of herbaceous plants in roughly a dozen genera. Often they are quite remarkable plants, more often red than green, without much leaf area and not growing very big in any way.The APG II system,...
, Cactaceae, CampanulaceaeCampanulaceaeThe family Campanulaceae , of the order Asterales, contains about 2000 species in 70 genera of herbaceous plants, shrubs, and rarely small trees, often with milky non-toxic sap...
, CaricaceaeCaricaceaeCaricaceae are a family of flowering plants in the order Brassicales, native to tropical regions of Central and South America and Africa. They are short-lived evergreen pachycaul shrubs or small trees growing to 5-10 m tall...
, Cartonemataceae, ChenopodiaceaeChenopodiaceaeChenopodiaceae were a family of flowering plants, also called the Goosefoot Family. They are now included within family Amaranthaceae. The vast majority of Chenopods are weeds, and many are salt and drought tolerant. A few food crops also belong to the family: spinach, beets, chard, quinoa, and...
, ConvolvulaceaeConvolvulaceaeConvolvulaceae, known commonly as the bindweed or morning glory family, are a group of about 60 genera and more than 1,650 species of mostly herbaceous vines, but also trees, shrubs and herbs.- Description :...
, Cycadaceae, CyclanthaceaeCyclanthaceaeCyclanthaceae is a family of flowering plants.-Classification:The APG system and the APG II system assign it to the order Pandanales in the clade monocots...
, DioscoreaceaeDioscoreaceaeDioscoreaceae is a family of monocotyledonous flowering plants, with about 750 species in eight or nine genera. The best-known member of the family is the Yam ....
, EricaceaeEricaceaeThe Ericaceae, commonly known as the heath or heather family, is a group of mostly calcifuge flowering plants. The family is large, with roughly 4000 species spread across 126 genera, making it the 14th most speciose family of flowering plants...
, EriocaulaceaeEriocaulaceaeThe Eriocaulaceae or pipewort family is a family of monocotyledonous flowering plants in the order Poales. The family is large, with about 1,150-1,200 species described in ten genera. The family is widely distributed, with the centers of diversity for the group occurring in tropical regions,...
, Gnetaceae, Guttiferae, HydrocharitaceaeHydrocharitaceaeHydrocharitaceae is a flowering plant family that includes a number of species of aquatic plant, broadly called the Tape-grasses, and includes the well known Canadian Waterweed and Frog's Bit.The family includes both fresh and marine aquatics...
, IridaceaeIridaceaeThe Iris family or Iridaceae is a family of perennial, herbaceous and bulbous plants included in the monocot order Asparagales, taking its name from the genus Iris. Almost worldwide in distribution and one of the most important families in horticulture, it includes more than 2000 species...
, JuglandaceaeJuglandaceaeThe Juglandaceae, also known as the Walnut Family, is a family of trees, or sometimes shrubs, in the order Fagales. Various members of this family are native to the Americas, Eurasia, and Southeast Asia....
, JuncaceaeJuncaceaeJuncaceae, the rush family, are a monocotyledonous family of flowering plants. There are eight genera and about 400 species. Members of the Juncaceae are slow-growing, rhizomatous, herbaceous plants, and they may superficially resemble grasses. They often grow on infertile soils in a wide range...
, Labiatae, Lacistemnaceae, LauraceaeLauraceaeThe Lauraceae or Laurel family comprises a group of flowering plants included in the order Laurales. The family contains about 55 genera and over 3500, perhaps as many as 4000, species world-wide, mostly from warm or tropical regions, especially Southeast Asia and South America...
, LecythidaceaeLecythidaceaeThe Lecythidaceae comprise a family of about 20 genera and 250-300 species of woody plants native to tropical South America and Madagascar.According to the most recent molecular analysis of Lecythidaceae The Lecythidaceae comprise a family of about 20 genera and 250-300 species of woody plants...
, LentibulariaceaeLentibulariaceaeLentibulariaceae is a family of carnivorous plants containing three genera, Genlisea, the corkscrew plants, Pinguicula, the butterworts, and Utricularia, the bladderworts....
, LiliaceaeLiliaceaeThe Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
, LoganiaceaeLoganiaceaeLoganiaceae are a family of flowering plants classified in order Gentianales. The family includes 13 genera, distributed around the world's tropics.Earlier treatments of the family have included up to 29 genera...
, Malphigiaceae, MayacaceaeMayacaceaeMayaca is a genus of flowering plants, often placed in its own family, the Mayacaceae. In the APG II system of 2003, it is assigned to the Order Poales in the clade commelinids. The Cronquist system, of 1981, also recognised such a family and placed it in the order Commelinales in the subclass...
, MelastomataceaeMelastomataceaeright|thumb|200px|Characteristic venation of many melastomesThe family Melastomataceae is a taxon of dicotyledonous flowering plants found mostly in the tropics comprising some 200 genera and 4500 species...
, MeliaceaeMeliaceaeThe Meliaceae, or the Mahogany family, is a flowering plant family of mostly trees and shrubs in the order Sapindales....
, MyristicaceaeMyristicaceaeMyristicaceae is the botanical name for a family of flowering plants. The family has been recognised by most taxonomists; it is sometimes called the "nutmeg family", after its most famous member, Nutmeg ....
, MyrtaceaeMyrtaceaeThe Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...
, MyrsinaceaeMyrsinaceaeMyrsinaceae, or the Myrsine family, is a rather large family from the order Ericales. It consists of 35 genera and about 1000 species....
, NymphaeaceaeNymphaeaceaeNymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...
, OlacaceaeOlacaceaeOlacaceae is a family of flowering plants in the order Santalales. They are woody plants, native throughout the tropical regions of the world....
, OxalidaceaeOxalidaceaeThe Oxalidaceae, or wood sorrel family, are a small family of eight genera of herbaceous plants, shrubs and small trees, with the great majority of the 900 species in the genus Oxalis...
, PedaliaceaePedaliaceaePedaliaceae is a flowering plant family classified in the order Scrophulariales in the Cronquist system and Lamiales in the Angiosperm Phylogeny Group system...
, PodocarpaceaePodocarpaceaePodocarpaceae is a large family of mainly Southern Hemisphere conifers, comprising about 156 species of evergreen trees and shrubs. It contains 19 genera if Phyllocladus is included and if Manoao and Sundacarpus are recognized....
, PolygonaceaePolygonaceaePolygonaceae is a family of flowering plants known informally as the "knotweed family" or "smartweed family"— "buckwheat family" in the United States. The name is based on the genus Polygonum and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum. The name refers...
, PontederiaceaePontederiaceaePontederiaceae is the botanical name of a family of flowering plants.The APG II system, of 2003 places the family in the order Commelinales, in the commelinid clade, in the monocots. It is a small family of heterostylous aquatic plants, occurring in tropical and subtropical waters...
, PotamogetonaceaePotamogetonaceaeThe Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of monocotyledonous flowering plants. There are roughly 120 species spread across six genera in the Potamagetonaceae...
, PrimulaceaePrimulaceaePrimulaceae is a family of flowering plants with about 24 genera, including some favorite garden plants and wildflowers. It is also known as the primrose family.- Genera :...
, ProteaceaeProteaceaeProteaceae is a family of flowering plants distributed in the Southern Hemisphere. The family comprises about 80 genera with about 1600 species. Together with the Platanaceae and Nelumbonaceae they make up the order Proteales. Well known genera include Protea, Banksia, Embothrium, Grevillea,...
, RanunculaceaeRanunculaceaeRanunculaceae are a family of about 1700 species of flowering plants in about 60 genera, distributed worldwide....
, RhamnaceaeRhamnaceaeRhamnaceae, the Buckthorn family, is a large family of flowering plants, mostly trees, shrubs and some vines.The family contains 50-60 genera and approximately 870-900 species. The Rhamnaceae have a worldwide distribution, but are more common in the subtropical and tropical regions...
, RosaceaeRosaceaeRosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...
, RubiaceaeRubiaceaeThe Rubiaceae is a family of flowering plants, variously called the coffee family, madder family, or bedstraw family. The group contains many commonly known plants, including the economically important coffee , quinine , and gambier , and the horticulturally valuable madder , west indian jasmine ,...
, RutaceaeRutaceaeRutaceae, commonly known as the rue or citrus family, is a family of flowering plants, usually placed in the order Sapindales.Species of the family generally have flowers that divide into four or five parts, usually with strong scents...
, SalicaceaeSalicaceaeSalicaceae are a family of flowering plants. Recent genetic studies summarized by the Angiosperm Phylogeny Group has greatly expanded the circumscription of the family to contain 55 genera....
, SapindaceaeSapindaceaeSapindaceae, also known as the soapberry family, is a family of flowering plants in the order Sapindales. There are about 140-150 genera with 1400-2000 species, including maple, horse chestnut and lychee....
, SaxifragaceaeSaxifragaceaeSaxifragaceae is a plant family with about 460 known species in 36 genera. In Europe there are 12 genera.The flowers are hermaphroditic and actinomorphic...
, SmilacaceaeSmilacaceaeSmilacaceae, the greenbrier family, is a family of flowering plants. Up to some decades ago the genera now included in family Smilacaceae were often assigned to a more broadly defined family Liliaceae, but for the past twenty to thirty years most botanists have accepted Smilacaceae as a distinct...
, SolanaceaeSolanaceaeSolanaceae are a family of flowering plants that include a number of important agricultural crops as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...
, TheaceaeTheaceaeThe Theaceae is a family of flowering plants, composed of shrubs and trees. Some botanists include the family Ternstroemiaceae within the Theaceae while others do not...
, TiliaceaeTiliaceaeTiliaceae is a botanical name for a family of flowering plants. Such a family is not part of APG II, but it is found all through the botanical literature and remains prominently listed by nomenclatural databases such as IPNI....
, Trioridaceae, TyphaceaeTyphaceaeTyphaceae is the botanical name for a family of flowering plants. Such a family has been recognized by most taxonomists.The APG II system, of 2003 , also recognizes this family, and assigns it to the order Poales in the clade commelinids, in the monocots...
, VitaceaeVitaceaeVitaceae are a family of dicotyledonous flowering plants including the grapevine and Virginia creeper. The family name is derived from the genus Vitis...
, ViolaceaeViolaceaeViolaceae are a family of flowering plants consisting of about 800 species in 21 genera. It takes its name from the genus Viola, the violets and pansies.Older classifications such as the Cronquist system placed Violaceae in an order named after it, the Violales...
, WinteraceaeWinteraceaeThe Winteraceae are a family of flowering plants. The family includes 120 species of trees and shrubs in 9 genera.The Winteraceae are a mostly southern-hemisphere family associated with the Antarctic flora, found in tropical to temperate climate regions of Malesia, Oceania, eastern Australia, New...
, XyridaceaeXyridaceaeXyridaceae is the botanical name of a family of flowering plants. Such a family has been recognized by many taxonomists and is known as the Yellow-eyed-grass Family....
, ZygophyllaceaeZygophyllaceaeThe Zygophyllaceae is a family of flowering plants that contains the bean-caper and caltrop. It includes around 285 species in 22 genera.In the APG III system of classification, the families Zygophyllaceae and Krameriaceae compose the order Zygophyllales...
Archaeology
Phytoliths are very robust in nature, and are useful in archaeologyArchaeology
Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...
, because they can be used to reconstruct the plants present at a site or an area within a site even though the rest of the plant parts have been burned up or dissolved. Because they are made of the inorganic substances silica or calcium oxalate, phytoliths don't decay when the rest of the plant decays over time and can survive in conditions that would destroy organic residues. Phytoliths can provide evidence of both economically important plants and those that are indicative of the environment at a particular time period.
Phytoliths may be extracted from residue on many sources: dental calculus (buildup on teeth); food preparation tools like rocks, grinders, and scrapers; cooking or storage containers; ritual offerings; and garden areas.
Sampling Strategies
- Cultural Contexts: The most important consideration when designing a sampling strategy for a cultural context is to fit the sampling design to the research objectives. For example, if the objective of the study is to identify activity areas, it may be ideal to sample using a grid system. If the objective is to identify foodstuffs, it my be more beneficial to focus on areas where food processing and consumption took place. It is always beneficial to sample ubiquitously throughout the site, because it is always possible to select a smaller portion of the samples for analysis from a larger collection. Samples should be collected and labeled in individual plastic bags. It is not necessary to freeze the samples, or treat them in any special way because silica is not subject to decay by microorganisms.
- Natural Contexts: Sampling a natural context, typically for the purpose of environmental reconstruction, should be done in a context that is free of disturbances. Human activity can alter the makeup of samples of local vegetation, so sites with evidence of human occupation should be avoided. Bottom deposits of lakes are usually a good context for phytolith samples, because wind often will carry phytoliths from the topsoil and deposit them on water, where they will sink to the bottom, very similar to pollen. It is also possible and desirable to take vertical samples of phytolith data, as it can be a good indicator of changing frequencies of taxa over time.
- Modern Surfaces: Sampling modern surfaces for use with archeobotanical data may be used to create a reference collection, if the taxa being sampled are known. It may also serve to "detect downward movement of phytoliths into archaeological strata". Taking point samples for modern contexts is ideal.
Laboratory Analysis
The first step in the laboratory analysis of phytolith samples is processing, in order to extract the phytoliths from the soil. Phytoliths can be extracted from soil samples in two ways: chemically or by ashing. After processing, microscopy is used to identify the phytoliths. Optical microscopeOptical microscope
The optical microscope, often referred to as the "light microscope", is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly designed in their present compound form in the...
s with magnifications of 200-400x are typically used to screen phytoliths. Scanning electron microscopy may also allow for a more detailed study of phytoliths.
Contribution to Archaeobotanical Knowledge
- Phytolith analysis is particularly useful in tropical regions, where other types of plant remains are typically not well preserved.
- Phytolith analysis has been used to retrace the domestication and ancestral lineage of various plants. For example, research tracing modern lineages of maize in South America and the American Southwest using phytolith remains on ceramics and pottery has proven to be enlightening. Recent genetic data suggests that the oldest ancestor of Zea mays is teosinte, a wild grass found in southwest Mexico. The Zea mays lineage split off from this grass about six to seven thousand years ago. Phytolith analyses from Bolivia suggest that several varieties of maize were present in the Lake TiticacaLake TiticacaLake Titicaca is a lake located on the border of Peru and Bolivia. It sits 3,811 m above sea level, making it the highest commercially navigable lake in the world...
region of Bolivia almost 1000 years before the TiwanakuTiwanakuTiwanaku, is an important Pre-Columbian archaeological site in western Bolivia, South America. Tiwanaku is recognized by Andean scholars as one of the most important precursors to the Inca Empire, flourishing as the ritual and administrative capital of a major state power for approximately five...
expansion, when it was previously thought to have been introduced in the region. This case is not isolated. Around the same time, certain varieties of maize could be found with ubiquity across part of South America, suggesting a highly frequented and established trade route existed. Phytolith data from the southeastern United States suggest that two different lineages of maize were introduced from two different sources. Research that hopes to discover more specific information about the spread of maize throughout the southeastern United States is currently under way. - To date, phytolith analyses have also been popular for studies of riceRiceRice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
. Because the morphologyMorphology (biology)In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
of rice phytoliths has been significantly documented, studies concerning the domestication of rice, as well as crop processing models using phytolith analyses, are insightful. In one study, phytolith analysis was used to complement macro-remains sampling in order to infer concentrations of plant parts and predict crop processing stages.
Problems with Phytolith Analysis of Remains
- Multiplicity- different parts of a single plant may produce different phytoliths.
- Redundancy- different plants can produce the same kind of phytolith.
It is suggested that using phytolith data from food residues (on ceramics, usually) can decrease the bias from both of these problems, because phytolith analysis is more likely to represent crop products and identification of phytoliths can be made with more confidence. Also, food residues do not usually accumulate extraneous deposits. In other words, the samples are more likely to represent a primary context.
Palaeontology
Phytoliths are abundant in the fossil record, and have been reported from the Late Devonian onwards. They can be used to identify palaeoenvironments and track vegetational change.Occasionally, paleontologists find and identify phytoliths associated with extinct plant-eating animals (i.e. herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s). Findings such as these reveal useful information about the diet of these extinct animals, and also shed light on the evolutionary history of many different types of plants. Paleontologists in India have recently identified grass phytoliths in dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
dung
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
(coprolite
Coprolite
A coprolite is fossilized animal dung. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour rather than morphology. The name is derived from the Greek words κοπρος / kopros meaning 'dung' and λιθος / lithos meaning 'stone'. They...
s), strongly suggesting that the evolution of grasses began earlier than previously thought.
Japanese and Korean archaeologists refer to grass and crop plant phytoliths as 'plant opal' in archaeological literature.
Carbon sequestration
Recent work since 2005 has shown that carbon can be accumulated in phytoliths. This suggests an opportunity to sequester carbonCarbon capture and storage
Carbon capture and storage , alternatively referred to as carbon capture and sequestration, is a technology to prevent large quantities of from being released into the atmosphere from the use of fossil fuel in power generation and other industries. It is often regarded as a means of mitigating...
securely in the long term, in the form of inclusions in durable silica. The relevance of phytoliths as a medium to assist in dealing with the problem of carbon sequestration remains to be established in an appropriate perspective, however carbon in phytoliths is in organic form, chemically reduced, as opposed to carbon dioxide, or even to elemental carbon. However desirable sequestration of carbon may turn out to be in principle, sequestration of unoxidised carbon is equivalent to discarding fuel unused. This in turn implies a cost to allow for in any rational energy budget.
See also
- Druse (botany)Druse (botany)Druse are groups of crystals of calcium oxalate, silicates or carbonates present in plants. Calcium oxalate crystals are found in algae, angiosperms and gymnosperms in a total of more than 215 families. These plants accumulate oxalate in the range of 3%-80% of their dry weight via a...
crystals of calcium oxalate, silicates, or carbonates present in plants - Raphide elongate calcium oxalate crystals in plants
External links
- What is the phytolith?
- Ecological significance of phytoliths
- Background from St. Cloud laboratory
- Association of Environmental Archaeology
- Steve Archer, "About Phytoliths": http://research.history.org/Archaeological_Research/Collections/CollArchaeoBot/PhytoFAQs.cfm .
- Terry B. Ball, "Phytolith Literature Review": http://www.ou.edu/cas/botany-micro/ben/ben282.html .
- Dr. Sanjay Eksambekar's 'Phytolith Research Institute': http://www.phytolithresearch.com
- Deborah Pearsall's MU Phytolith Database ,http://web.missouri.edu/~umcasphyto/index.shtml
- "What are Phytoliths?" Sandstone Archaeology Paleoethnobotany Laboratory http://www.sandstonearchaeology.com/paleoethnobotany.html