Ligule: The membranous appendage arising from the inner surface of the leaf at the junction with the leaf sheath in many grasses and some sedges.*
In grasses, the ligule is an important identification characteristic. For instance, in Phragmites, the ligule can help you tell whether you’re looking at the invasive or the native subspecies. The native Phragmites has a wider ligule than the invasive variety.
Thank you to Lynn Short of Humber College and her important research in controlling the invasive Phramites australis subsp. australis.
Note: Outside of the grasses, the word ‘ligule’ can have other meanings. See the previous BNW post: Ligulate.
*Harris, J.G., Harris, M.W. (2001). Plant identification terminology: An illustrated glossary (2nd ed.). Spring Lake: Spring Lake Publishing.