Diagrams of the grass inflorescences (A) and spikelets (B). Pictograms of rice (Oryza stavia) and sorghum (Sorghum bicolor) panicle, maize (Zea mays) tassel, barley (Hordeum vulgare), wheat (Triticum aestivum) and Brachypodium distachyon spike, and Setaria viridis inflorescences (A) and spikelets (B). Note that the spikelet is the structural unit of grasses inflorescence, and the diverse growth patterns of the spikelets confers inflorescence complexity (see text for details). a awn, br bristle, le lemma, f flower, gl glume, LB lateral branch, pa palea, PB primary branch, PS pedicellate spikelet, RA rachis, rg rudimentary glume, SB secondary branch, sl sterile lemma, SP spikelet, SS sessile spikelets