The structure that partially clasps a grass stem at the blade–sheath junction and has species-specific characteristics based on its presence and form.

The structure that partially clasps a grass stem at the blade–sheath junction and has species-specific characteristics based on its presence and form.

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

Answer: (A)

The ligule is a small structure located at the blade–sheath junction that partially clasps the stem. Its presence or absence, and its form (membranous, hairy, short, long, etc.), vary among grass species, which is why this feature is used to differentiate turfgrasses. The other parts refer to different plant structures: the node is a stem joint where leaves attach, the sheath is the wrapping around the stem at the base of the leaf, and the blade is the flat leaf portion. So the ligule uniquely matches the description of being at the blade–sheath junction with species-specific variation.

The ligule is a small structure located at the blade–sheath junction that partially clasps the stem. Its presence or absence, and its form (membranous, hairy, short, long, etc.), vary among grass species, which is why this feature is used to differentiate turfgrasses. The other parts refer to different plant structures: the node is a stem joint where leaves attach, the sheath is the wrapping around the stem at the base of the leaf, and the blade is the flat leaf portion. So the ligule uniquely matches the description of being at the blade–sheath junction with species-specific variation.