Figure 2.

Auxin plays a role in axillary meristem initiation in the inflorescence. A, Arabidopsis inflorescence with secondary branches (br) and flowers (fl). B, pid mutant in Arabidopsis showing the pin-shaped inflorescence due to lack of flower production. C, Normal maize tassel with long branches (br) at the base of the main spike. Short branches called spikelet pairs (sp) cover the branches and the central spike. D, bif2 mutant of maize with very few branches and spikelets. [See online article for color version of this figure.]