Biogenic Opal in Three Species of Gramineae

Particulate biogenic opaline silica is concentrated in cellwalls, intercellular deposits and cell lumina of all portionsof the above-ground plant body of three species of PanicoidGramineae,Andropogon gerardi, Sorgastrum nutans and Panicumvirgatum. Morphologically distinct opal phytoliths form notonly in long cells, short cells, trichomes, stomatal elementsand bulliform cells of the epidermis but also within the cellularstructure of mesophyll, vascular, and sclerenchyma tissues.Roots and rhizomes contain measurable quantities of opalinesilica, and phytoliths develop in epidermal long cells, saddle-shapedshort cells, vascular cells, and intercellular deposits. A morphologicallyunique plate-phytolith, formed by silicification of the innertangential wall of the endodermis, is present in the roots ofall three species. Differences in the quantity of opaline silicaoccur between species and between parts of the same species.The amount of opal deposited in the soil annually by root systemsand above-ground parts is approximately equal in magnitud Andropogon gerardi, Sorgastrum nutans, Panicum virgatum, opaline silica deposition