What distinguishes rushes from other similar plants?

Rushes are distinguished from other similar plants primarily by their hollow cylindrical stems. This structural characteristic is a key identifying feature of rushes, setting them apart from other plant types such as sedges and grasses, which do not have this specific stem structure. The hollow stems contribute to their unique appearance and adaptability to wetland environments where they commonly grow.

While rushes can grow in dense clumps, which might be seen in some other types of plants as well, this growth habit alone is not distinctive enough to set them apart in the same way that their hollow stems do. The nature of their leaves is also a point of differentiation—rushes usually have narrow, linear leaves that do not compare to the broad leaves found in many other plant species. Furthermore, rushes can be either annual or perennial, which means that being an annual plant is not a consistent characteristic that helps define them. Therefore, the hollow cylindrical stems are the most definitive feature of rushes, making this the correct distinguishing trait.