Which of the following characteristics defines grasses?

Grasses are classified as monocots, which means they have one seed leaf, commonly referred to as a cotyledon. This characteristic is significant as it fundamentally differentiates them from dicots, which have two seed leaves. In addition to having a single seed leaf, grasses typically have narrow and upright leaves, which are a result of their adaptation to a variety of environments. Their leaf structure also allows them to effectively capture sunlight while minimizing water loss, which is crucial for their survival in a range of climates.

The presence of narrow leaves contributes to the overall growth form of grasses, which is often vertical and clump-like, enabling them to thrive in diverse ecosystems. They often play important roles in soil stabilization and provide habitats for various wildlife species. Grasses also exhibit a variety of growth habits, including annual and perennial types, but the defining characteristic in this context is indeed the presence of a single seed leaf.