Biogenic Opal in Three Species of Gramineae

Particulate biogenic opaline silica is concentrated in cell walls, intercellular deposits and cell lumina of all portions of the above-ground plant body of three species of Panicoid Gramineae, Andropogon gerardi , Sorgastrum nutans and Panicum virgatum . Morphologically distinct opal phytoliths form not only in long cells, short cells, trichomes, stomatal elements and bulliform cells of the epidermis but also within the cellular structure of mesophyll, vascular, and sclerenchyma tissues. Roots and rhizomes contain measurable quantities of opaline silica, and phytoliths develop in epidermal long cells, saddle-shaped short cells, vascular cells, and intercellular deposits. A morphologically unique plate-phytolith, formed by silicification of the inner tangential wall of the endodermis, is present in the roots of all three species. Differences in the quantity of opaline silica occur between species and between parts of the same species. The amount of opal deposited in the soil annually by root systems and above-ground parts is approximately equal in magnitud