What is the structure which partially clasps a grass stem at the junction of the blade and the sheath, whose size, shape and texture help identify species? To see it, peel the leaf away and examine it with a hand lens.

• A. Ligule
• B. Node
• C. Sheath
• D. Blade

Answer: (A)

The structure at the leaf collar that partly clasps the grass stem where the blade meets the sheath is the ligule. It sits at the junction of the blade and the sheath and is often a small, membranous or hairy projection. The ligule varies in size, shape, and texture between species, so inspecting it—by peeling the leaf away from the sheath and looking at the edge with a hand lens—provides a useful identifying feature. The other options don’t fit: the node is a point on the stem where leaves attach along the internode, not at the blade-sheath junction; the sheath is the wrapping around the stem; and the blade is the flat part of the leaf itself, not a distinct clamping structure at the junction.