The hydraulic architecture of parallel veined monocots is fundamentally different from the branched networks of dicot leaves. The functional significance of this difference on leaf level gas exchange is not well understood. In order to investigate how the hydraulic architecture of monocots affect gas exchange we measured the axial hydraulic conductivity and leaf level gas exchange from the base to tip of 7 grass species. Stomatal conductance (g_s) and photosynthesis (A) increased but hydraulic conductivity (K_h) declined along the length of the blade. When Kh was normalized by leaf area (K_h*leaf), however, K_h*leaf was constant along the blade. There were also differences in the relationship between K_h and g_s between C3 and C4 grasses. Increasing gs is one mechanism to create lower leaf water potentials along a grass blade in order for water to move down the free energy gradient (from base to tip). This research highlights the unique relationship between gas exchange and water movement in parallel veined plants.