Ligule
/ˈlɪɡjuːl/
Definition
Ligule refers to a small, thin outgrowth of plant tissue. In grasses and many grass-like plants, it sits at the junction where the leaf blade meets the leaf sheath and may be membranous or a fringe of hairs. This structure helps distinguish species. In some composite flowers, the term can also describe the strap-shaped part of a ray floret, such as the petal-like edge of a daisy head.
Function in Plants
- Grass leaf protection: In grasses, ligule sits where the leaf blade meets the sheath and can help limit water, dust, and small particles from moving into the sheath around the stem.
- Useful for plant identification: Its presence, shape, size, and whether it is membranous or made of hairs are important characters in identifying grasses and separating similar species.
- Key trait in grass taxonomy: Botanists often record ligule features in floras and identification keys because they are visible, fairly consistent, and useful in classification within the grass family.
- Practical value when examining turf and weeds: Looking at ligule can help distinguish common lawn grasses and grassy weeds at an early stage, before flowering structures appear and make identification easier.
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