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How do leaf sheaths help support grass stems?

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wild rice — Poaceae Wild rice (*Zizania aquatica*).

In the Poaceae family, leaf sheaths play a vital role in providing structural support to the grass stem, also known as a culm. These sheaths arise at the nodes and encircle the internode located above them. By doing so, they effectively counter the tendency for the internode to bend at its basal growing point, which is the area where the stem is structurally weakest.1