Grass is characterized by which feature?

• A. Flat or round, hollow stems
• B. Woody stems
• C. Parallel leaf veins
• D. Flowers in threes.

Answer: (A)

Grass plants are defined by their hollow, jointed stems called culms. These stems can be flat or round, but the interior is typically hollow between the nodes, giving the plant a light, flexible structure that supports rapid growth and grazing resilience. This hollow stem feature is a reliable characteristic that helps distinguish grasses from many other plant groups, especially woody plants that have solid or woody stems.

While parallel leaf veins are also a common trait in grasses (they’re monocots), that feature is shared with many other monocot plants and isn’t as diagnostic on its own. Flowers in threes describe many monocots but grasses have small, specialized flowers arranged in spikelets within inflorescences, not in simple threes. So the hollow stems stand out as the best single trait to identify grasses.