Patchy stomatal conductance: emergent collective behaviour of stomata

Until recently, most scientists have tacitly assumed that individual stomata respond independently and similarly to stimuli, showing minor random variation in aperture and behaviour. This implies that stomatal behaviour should not depend on the scale of observation. However, it is now clear that these assumptions are often incorrect. Leaves frequently exhibit dramatic spatial and temporal heterogeneity in stomatal behaviour. This phenomenon, in which small 'patches' of stomata respond differently from those in adjacent regions of the leaf, is called 'patchy stomatal conductance'. It appears to represent a hitherto unknown type of emergent collective behaviour that manifests itself in populations of stomata in intact leaves.