This Tiny Tube Is Why Grass Is Everywhere

Imagine a clump of grass with a spray of green blades that come together into tubes. The sheath of the grass leaf is where the tubes are formed. It allows grass to grow from the base by protecting new growth and keeping mature blades upright so they can compete for sunlight. Grasses dominate more than a quarter of Earth's land area because they grow better than stem-growing competitors.

The sheath is found in all grasses and has been debated by scientists. A new study in Science shows how the grass leaf arose from the same genetic pattern that governs other plants.