right|thumb|Portrait of John Martyn
John Martyn or Joannes Martyn (12 September 1699 – 29 January 1768) was an English botanist.
Career
Martyn was born in London, the son of a merchant. He attended a school in the vicinity of his home, and when he turned 16, worked for his father, intending to follow a business career. He married Marie Anne Fonnereau, daughter of Claude Fonnereau, a Huguenot refugee who had settled in England and become a successful merchant. Martyn abandoned his business pursuits in favour of medical and botanical studies. His interest in botany came from his acquaintance with an apothecary, John Wilmer, and Dr. Patrick Blair, a surgeon-apothecary from Dundee who practiced in London. Martyn gave some botanical lectures in London in 1721 and 1726, and in 1727 was elected a Fellow of the Royal Society of London.
Martyn was one of the founders together with Johann Jacob Dillenius and others, as well as the secretary of a botanical society which met for a few years in the Rainbow coffee-house, Watling Street. An expanded version of this memoir was prepared and published by George Gorham in 1830.
Historia Plantarum Rariorum
Martyn is best known for his Historia Plantarum Rariorum written between 1728 and 1737 with illustrations by Jacob van Huysum. Martyn is also known for his translation, with valuable agricultural and botanical notes, of the 1749 Eclogues and the 1741 Georgics by Virgil. He also started the Grub Street Journal, a weekly satirical review, which lasted from 1730 to 1737.