Figure 10. Strahler bifurcation ratio for the various generated, optimized and natural graphs.
Red error bar: standard error of the linear regression fit (represents goodness of linear fit). Black error bar: standard deviation of the logarithm of the bifurcation ratio (average over 20 realizations). Insets: Number of Strahler streams 
of order 
as a function of 
for the random lines, nested and gradient model and the Bursera leaf. Note that in each case, the 
follows closely an inverse geometric progression with 
(shown with the red dashed line).