Across angiosperms, nectaries can be found on virtually every part of the flower, yet within each species, they consistently form in a specific location. What mechanisms underlie this combination of evolutionary flexibility and developmental consistency?

In Mimulus, nectaries develop at the base of the carpel—an anatomical intersection of multiple lateral organ polarity axes: proximal-distal, adaxial-abaxial, and dorsal-ventral. These polarity axes form a three-dimensional coordinate system that precisely defines nectary position. But how are these spatial signals perceived by developing tissues?

Previous studies have identified the transcription factor CRABS CLAW (CRC) as a key regulator of nectary identity in several species. Floral organ identity genes are known to directly bind and regulate CRC, thereby determining the floral organs with which nectaries are associated. This raises a compelling question: could polarity signals also converge on the CRC locus to specify the precise spatial location of nectary formation? Mimulus’s unique nectary location and its amenability for rapid stable transformation provide an exciting case to test this hypothesis.