Sheath
/ʃið/
Definition
Sheath refers to a tubular or wrapping plant structure that closely encloses another part, most often the base of a leaf around a stem. It differs from a blade, which is the flat, expanded part of a leaf. Leaf sheaths are common in grasses, sedges, and many monocots, where they support and protect young tissues and may be open or closed along one side.
Function in Plants
- Leaf support in grasses: In grasses, sedges, and many grass-like plants, the sheath helps hold the leaf close to the stem, adding support while the blade extends outward for light capture.
- Protection of young tissues: A sheath can enclose soft developing parts near the stem, reducing physical damage and helping shield growing tissue as new leaves emerge.
- Useful identification feature: Botanists often examine whether the sheath is open or closed, smooth or hairy, because these traits can help distinguish plant families, genera, or similar-looking species.
- Clues during plant care: When a sheath stays wrapped around older tissue, it may trap moisture or debris, which can sometimes encourage rot or pest hiding places in dense growth.
Related Terms
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Ligule
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Internode
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