ligule

noun

(L. ligula: little tongue) A strap-shaped structure; a hyaline, membranous or hairy appendage on the adaxial surface of a leaf, especially in grasses, at the junction between sheath and blade; a small adaxial appendage near the leaf base in some pteridophytes, e.g. a tongue-like projection borne at the base of the leaves above the sporangia in Isoetes; the corolla limb in ray flowers of Asteraceae.