Figure 1.

The abscission zone (AZ) position may shift from rachilla down to pedicel and rachis during evolution. (a) A diagram illustrating different AZ positions: below caryopsis and above lemma and palea (orange), in the rachilla below floret and above the glumes (blue), in the pedicel below the glumes (green), or in the rachis or inflorescence branches (red). A floret includes caryopsis and floral bracts (palea and lemma). A spikelet (marked by dotted circle) includes florets and the subtending pair of glumes. (b) Ancestral state reconstruction of the AZ positions in the grass family. Big arrowheads point to rice, Brachypodium and Setaria. Small arrowheads point to examples of species with AZ positions different from other species within the tribe.