Stomatal traits relate to habitat preferences of herbaceous species in a temperate climate

•Stomatal size does not differ between adaxial and abaxial sides of leaves.•There is an increase in absolute variation of sizes and densities with increasing mean size and density respectively, but not in relative variation.•Stomatal distribution between the two sides of the leaf reflect species ecological strategies.•High light and low moisture demand is associated with equal distribution of stomata between leaf sides.•Water use efficiency is highest in amphistomatic species with high stomatal densities.