Which trait best distinguishes sedges from grasses?

• A. Solid triangular stems
• B. Hollow stems with ligules
• C. Net-like leaf veins
• D. Thick blue-green leaves

Answer: (A)

The key idea is the stem shape. Sedges can be distinguished by having solid stems that are triangular in cross-section—often described as “edges.” If you can feel or see a three-sided stem, you’re looking at a sedge. Grasses, by contrast, usually have hollow, round stems with joints, which is a different feel and structure. This difference in stem cross-section is a reliable, quick field cue to separate the two groups, especially since many other features can vary more and aren’t as consistently diagnostic. The other traits—hollow stems with ligules, net-like leaf veins, and thick blue-green leaves—don’t reliably differentiate sedges from grasses, because they can occur in grasses too or aren’t distinctive enough across species.