What is a defining feature of grasses?

Grasses are characterized by having hollow, cylindrical stems, which is an important distinction in plant morphology. This structural feature is not only significant for their growth and physiological functions but also aids in their adaptability within various environments. The hollow stems help reduce weight compared to solid stems, allowing grasses to sway in the wind without breaking easily. This adaptation is particularly beneficial in open fields and prairies where they are often found.

Additionally, the structure of their stems contributes to their overall resilience; they are designed to channel nutrients and water effectively throughout the plant. This characteristic sets grasses apart from many other plant groups, helping to identify them in various ecological settings.

The other options do not accurately describe grasses: solid, triangular stems are more typical of some sedges, while the assertion that grasses always flower in spring is misleading as flowering times can vary. Large, colorful flowers are not a defining trait of grasses either, as they tend to have more understated inflorescences adapted for wind pollination rather than showy blooms.