Observed mass accretion rate versus age in LH 91. Yellow filled squares and empty black triangles represent the targets with mass greater and smaller than the median mass of the PMS candidates sample, respectively. The gray-filled dots are the PMS candidates in LH 95 (Biazzo et al. 2019). The error bars on the age and mass accretion rate are reported. When the uncertainties are smaller than the symbol size, they are not visible. The arrows represent lower limits. The dashed yellow and solid black lines represent the regression fit of the two subsamples of LH 91.