Vein and stomatal density showed small but coordinated
responses to growth under high and low VPD in T. ciliata,
contradicting our hypothesis that the balance between vein
and stomatal density would be modified to uphold transpirational
homeostasis. Furthermore, the direction of this
response was opposite to what was predicted (i.e. stomatal
density increased with VPD). Instead, substantial changes in
stomatal conductance maintained transpirational homeostasis
in plants grown under contrasting VPD treatments. Thus,
T. ciliata resorted to dynamic stomatal control rather than
disruption of a fixed relationship between vein and stomatal
tissue production. Consequently, the allocation of veins and
stomata during leaf development must be tightly linked.