Phytolith

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A Phytolith ("Plant stone") is a rigid microscopic body that occurs in many plants. The most common type of phytolith is the silicon phytolith, also called opal phytolith. Silicon phytoliths vary in size and shape depending on the plant taxon and plant part (stem, leaf, root) in which they (naturally) occur. Calcium oxalate phytoliths can occur in, e.g., cacti.

These objects apparently serve, at least in some cases, to give structural stability to leaves and stalks.

Grasses and similar plants (rice, wild rice, maize, various grains) as well as numerous tree species are just some of the plants which contain phytoliths.

Phytoliths are very robust in nature, and are useful in archaeology, 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. Occasionally, paleontologists find and identify phytoliths associated with extinct plant-eating animals (e.g., herbivores).

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 dung which strongly suggests the evolution of grasses earlier than previously thought [1].

Phytoliths are mentioned in the writings of Charles Darwin.

[edit] References

Thorn, V. C. 2004. An annotated bibliography of phytolith analysis and atlas of selected New Zealand subantarctic and subalphine phytoliths.
Meunier, J. D. 2001. Phytoliths: applications in earth sciences and human history.
Kealhofer, L. 1998. Opal phytoliths in Southeast Asian flora.
Rapp, G. R. 1992. Phytolith systematics: emerging issues.
Ciochon, R. L., Piperno, D. R. and Thompson, R. G. 1990. Opal phytoliths found on the teeth of the extinct ape Gigantopithecus blacki: Implications for paleodietary studies. Proc. Nat. Acad. Sci. 87: 8120-8124.
Piperno, D. R. 1988. Phytolith analysis: an archaeological and geological perspective.
Twiss, P. C., Suess, E., & Smith, R. M. 1969. Morphological classification of grass phytoliths. Proc. Soil Sci. Soc. America.