Lateral organs arise from individual or groups of cells
either on the flanks of meristems or within defined
cellular positional contexts. The first event in organogenesis
is founder cell specification. Auxin is one necessary
signal in different organ specification contexts, but
it is difficult to distinguish between correlative and
causal signals and evidence is emerging that other signals
exist and that the interplay between these signals is
important for organ initiation. This review analyses the
progress in understanding which signals contribute to
founder cell specification and outlines the emerging
complexities in the perception of positional information
that are context-dependent and reliant on the establishment
and coordination of different types of competencies.