What characteristic distinguishes grasses from other plants?

• A. Broad leaves with non-parallel veins
• B. Narrow, upright leaves with parallel veins
• C. Persistent woody tissue on branches
• D. Deep tap-root systems

Answer: (B)

Grasses are characterized by their narrow, upright leaves that feature parallel veins. This leaf structure is a key identifying trait of the Poaceae family, which includes all types of grasses. The presence of parallel veins reflects a unique adaptation to their environment, allowing for efficient water and nutrient transportation throughout the leaf. This feature differentiates grasses from many other plant groups, such as broadleaf plants, which typically exhibit a network of veins that are not parallel.

The characteristics mentioned in the other options refer to traits associated with different plant families. For instance, broad leaves with non-parallel veins are typical of many dicots, while persistent woody tissue is more common in shrubs and trees rather than herbaceous grasses. Similarly, deep tap-root systems can occur in various plant types but are not exclusive to grasses, which may have fibrous root systems instead. Thus, the defining leaf structure of grasses, with its narrow shape and parallel vein arrangement, is what sets them apart from other plant species.