Spectroscopic sequence of SN 2015H. Spectra have been corrected for redshift and galactic extinction. Epochs are given relative to maximum light at MJD = 57 061.9. Regions showing strong telluric features in the near-IR have been omitted. Near-IR spectra have also been smoothed, to highlight the features present. We also highlight the features discussed in Sect. 3.3 and those present throughout the spectroscopic evolution which were used for velocity measurements in Fig. 9. Arbitrary vertical offsets, and different colours for alternating spectral phases have been used for clarity.