Complex sentence: The 1633 edition of Gerard's "Herball" was edited by Thomas Johnson, an apothecary and botanist who lived in London, under commission from the heirs to the estate of John Gerard.
Split into simpler sentences: The 1633 edition of Gerard's "Herball" was done by Thomas Johnson, an apothecary and botanist who lived in London. He was commissioned to do the job by the heirs to the estate of John Gerard.