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Unformatted text preview: of the Equisetales The Equisetums may be the most distinctive plants on earth. They have hollow, jointed stems that are impregnated with silica. This gives a rough texture, and is the source of the common name for some Equisetums, scouring rushes. Some Equisetums have whorled axillary branches at the stem joints (which are really the nodes). The axillary branching fools some into thinking the branches are jointed leaves. They are not. The aerial stems arise from nodes of persistent below-ground rhizomes. The rhizomes allow survival in harsh environmental conditions. The mature stems have a hollow pith and two rings of canals in the cortex. The innermost canal, the carinal canal, has xylem and phloem and is used in conduction. The larger, outer canal is air-filled....
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- Fall '09