How the grass grows

Leaf of grass

The circle-shaped veins are relatively close together in this magnified cross-section of a leaf of Eriachne ciliata grass, and they are ringed by large “bundle sheath” cells. That anatomy promotes a more efficient “C4” means of photosythesis.  Credit: Edwards lab/Brown University

Two groups — clades — of grasses that once had a common ancestry diverged. The PACMAD clade was predisposed to evolve a more efficient “C4” means of photosynthesis than grasses in the BEP clade. In a new study in the Proceedings of the National Academy of Sciences, a Brown-led team pinpoints the anatomical differences between the clades that led to the PACMAD’s tendency toward C4.