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Phytolith
 
 
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A phytolith ("plant stone") is a rigid microscopic body that occurs in many plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s. The most common type of phytolith is the silica phytolith, also called opal
Opal

Opal is a mineraloid gel which is deposited at a relatively low temperature and may occur in the fissures of almost any kind of Rock , being most commonly found with limonite, sandstone, rhyolite, and basalt....
 phytolith. Silica phytoliths vary in size and shape depending on the plant taxon and plant part (stem
Plant stem

A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaf, inflorescence , conifer cones or other stems etc....
, leaf
Leaf

In botany, a leaf is an above-ground plant Organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin, to expose the cells containing chloroplast to light over a broad area, and to allow light to penetrate fully into the tissues....
, root
Root

In vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial root or aerating ....
) in which they (naturally) occur. Grasses
Poaceae

Poaceae or Gramineae is a family in the Class Liliopsida of the Magnoliophyta. Plants of this family are usually called grasses; the shrub- or tree-like plants in this family are called bamboo ....
, including rice
Rice

Rice is a staple food for a large part of the world's human population, especially in tropical Latin America, and East Asia, South Asia and Southeast Asia, making it the second-most consumed cereal grain, after maize....
, wild rice
Wild rice

Wild rice is any of the four species of plants that make up the genus Zizania , a group of Poaceae that grow in shallow water in small lakes and slow-flowing streams; often, only the flowering head of wild rice rises above the water....
, maize
Maize

Maize , known as corn in some countries, is a cereal domesticated in Mesoamerica and subsequently spread throughout the American continents....
, wheat, and other various grains); crop plants such as beans, squashes, gourds, manioc, canna, and arrowroot; palms; as well as numerous tree species are just some of the plants which contain phytoliths. Calcium oxalate
Calcium oxalate

Calcium oxalate is a chemical compound that forms needle-shaped crystals. Its chemical formula is CaC2O4 or Ca2....
 phytoliths are another common type, occurring in the stems of cacti
Cactus

A cactus is any member of the spine plant family Cactaceae, native to the Americas. They are often used as ornamental plants, but some are also Crop plants....
 and baobabs
Baobab

Baobab is the common name of a genus containing eight species of trees, native to Madagascar , mainland Africa and Australia . The mainland African species also occurs on Madagascar, but it is not a native of that country....
. Phytoliths are mentioned in the writings of Charles Darwin
Charles Darwin

Charles Robert Darwin Royal Society was an English people natural history who realised and presented compelling evidence that all species of life have evolution over time from common descent, through the process he called natural selection....
.

e objects serve a variety of purposes.






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A phytolith ("plant stone") is a rigid microscopic body that occurs in many plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s. The most common type of phytolith is the silica phytolith, also called opal
Opal

Opal is a mineraloid gel which is deposited at a relatively low temperature and may occur in the fissures of almost any kind of Rock , being most commonly found with limonite, sandstone, rhyolite, and basalt....
 phytolith. Silica phytoliths vary in size and shape depending on the plant taxon and plant part (stem
Plant stem

A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaf, inflorescence , conifer cones or other stems etc....
, leaf
Leaf

In botany, a leaf is an above-ground plant Organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin, to expose the cells containing chloroplast to light over a broad area, and to allow light to penetrate fully into the tissues....
, root
Root

In vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial root or aerating ....
) in which they (naturally) occur. Grasses
Poaceae

Poaceae or Gramineae is a family in the Class Liliopsida of the Magnoliophyta. Plants of this family are usually called grasses; the shrub- or tree-like plants in this family are called bamboo ....
, including rice
Rice

Rice is a staple food for a large part of the world's human population, especially in tropical Latin America, and East Asia, South Asia and Southeast Asia, making it the second-most consumed cereal grain, after maize....
, wild rice
Wild rice

Wild rice is any of the four species of plants that make up the genus Zizania , a group of Poaceae that grow in shallow water in small lakes and slow-flowing streams; often, only the flowering head of wild rice rises above the water....
, maize
Maize

Maize , known as corn in some countries, is a cereal domesticated in Mesoamerica and subsequently spread throughout the American continents....
, wheat, and other various grains); crop plants such as beans, squashes, gourds, manioc, canna, and arrowroot; palms; as well as numerous tree species are just some of the plants which contain phytoliths. Calcium oxalate
Calcium oxalate

Calcium oxalate is a chemical compound that forms needle-shaped crystals. Its chemical formula is CaC2O4 or Ca2....
 phytoliths are another common type, occurring in the stems of cacti
Cactus

A cactus is any member of the spine plant family Cactaceae, native to the Americas. They are often used as ornamental plants, but some are also Crop plants....
 and baobabs
Baobab

Baobab is the common name of a genus containing eight species of trees, native to Madagascar , mainland Africa and Australia . The mainland African species also occurs on Madagascar, but it is not a native of that country....
. Phytoliths are mentioned in the writings of Charles Darwin
Charles Darwin

Charles Robert Darwin Royal Society was an English people natural history who realised and presented compelling evidence that all species of life have evolution over time from common descent, through the process he called natural selection....
.

Function

These objects serve a variety of purposes. In many cases, they appear to lend the plant structure and support, much like the spicules
Spicule

Spicules are skeleton structures that occur in most Sea 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....
 in sponges and leather corals
Alcyonacea

The Alcyonacea, or the soft corals are an order of corals which do not produce calcium carbonate skeletons and so are neither reef-building corals nor do they lay new foundations for future corals....
. Others serve to make plants distasteful, lending the plant's tissues a grainy or prickly texture. Finally, calcium oxalate phytoliths serve as a reserve of carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
. Cacti use these as a reserve for photosynthesis
Photosynthesis

File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight....
 during the day when they close their pores to avoid water loss, while baobabs use this property to make their trunks more flame-resistant.

Archaeology

Phytoliths are very robust in nature, and are useful in archaeology
Archaeology

Archaeology, archeology, or arch?ology is the science that studies Homo cultures through the recovery, documentation, analysis, and interpretation of material remains and environmental data, including architecture, Artifact , features, Biofact s, and cultural landscape....
, since 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.

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 (e.g., herbivore
Herbivore

Herbivory is a form of predation in which an organism, known as an herbivore, heterotrophs principally autotrophs such as plants, algae and photosynthesizing bacteria....
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 were the dominant vertebrate animals of Landform ecosystems for over 160 million years, from the late Triassic Period until the end of the Cretaceous Period , when most of them became extinct in the Cretaceous?Tertiary extinction event....
 dung
Dung

Dung may refer to:* Dung, animal feces* Dung, Doubs, a commune in the Doubs department in France* Mundungus Fletcher , a character in Harry Potter...
, 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 in 2007 has shown that carbon can be accumulated in many phytoliths, and as such could provide a long term option to sequester carbon
Carbon capture and storage

Carbon capture and storage is an approach to Mitigation of global warming the contribution of fossil fuel emissions to global warming, based on capturing carbon dioxide from large Point source pollution such as fossil fuel power plants....
 in soil in the plant residual silica.

External links

  • 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