To cite phruta in publications use:

  Román-Palacios, C. (2021). The phruta R package: Phylogenetic
  Reconstruction and Time-dating.

A BibTeX entry for LaTeX users is

  @Misc{,
    title = {The phruta R package: Phylogenetic Reconstruction and Time-dating},
    author = {Cristian Román-Palacios},
    year = {2021},
  }