Templeton was born at Orange Grove, Belfast in 1766. He married Katherine Johnson of Seymour Hill, on the outskirts of Belfast, the daughter of a Belfast merchant on 21 December 1799. The couple had five children: Ellen, born on 30 September 1800, Robert, born on 12 December 1802, Catherine, born on 19 July 1806, Mary, born on 9 December 1809 and Matilda on 2 November 1813. The union between the two already prosperous merchant families provided more than ample means enabling Templeton to devote himself passionately to the study of natural history. Influenced by the French Revolution, which many saw as lighting a beacon of enlightenment before the counter-revolutionary Civil War and the ensuing "Terror", Templeton was an early member of the United Irishmen. At once a fervent advocate of Irish independence from the United Kingdom he changed the name of the family home to 'Cranmore'. Disillusionment came with the murders of a number of Protestants at Wexford bridge and the rise of sectarian Irish nationalism, though he remained a strenuous and enlightened advocate of civil and religious liberty. Never of strong constitution, he was not expected to survive, he was in failing health from 1815 and died in 1825 aged only 60, "leaving a sorrowing wife, youthful family and many friends and townsmen who greatly mourned his death". The Australian leguminous genus Templetonia is named for him. His son Robert became a famous entomologist.
Botany
John Templeton's interest in botany began with an experimental garden laid out according to a suggestion in Rousseau's 'Nouvelle Heloise' and following Rousseau's 'Letters on the Elements of Botany'. Here he cultivated many tender exotics out of doors and began botanical studies which lasted throughout his life and corresponded with the most eminent botanists in England Sir William Hooker, William Turner, James Sowerby and, especially Sir Joseph Banks, who had travelled on Captain James Cook's voyages, and in charge of Kew Gardens. Banks tried to tempt him to New Holland as a botanist on the Flinders's Expedition with the offer of a large tract of land and a substantial salary. An associate of the Linnean Society, Templeton visited London and saw the botanical work being achieved there. This led to his promotion of the Belfast Botanic Gardens as early as 1809, and to work on a Catalogue of Native Irish Plants, in manuscript form and now in the Royal Irish Academy, which was used as an accurate foundation for later work by succeeding Irish botanists. He also assembled text and executed many beautiful watercolour drawings for a Flora Hibernica, sadly never finished, and kept a detailed Journal during the years 1806–1825. Of the 12000 algal specimens in the Ulster MuseumHerbarium about 148 are in the Templeton collection and were mostly collected by him, some were collected by others and passed to Templeton. The specimens in the Templeton collection in the Ulster Museum have been catalogued. Those noted in 1967 were numbered: F1 – F48. Others were in The Queen's University Belfast. Queens University Belfast All of Templeton's specimens have now been numbered in the Ulster Museum as follows: F190 – F264; F290 – F314 and F333 – F334. Templeton was the first finder of Rosa hibernica and in Ireland of Sisymbrium Ligusticum seoticum, Adoxa moschatellina, Orobanche rubra and many other plants.
John Templeton had wide-ranging scientific interests including chemistry as it applied to agriculture and horticulture, meteorology and phenology following Robert Marsham. He published very little aside from monthly reports on natural history and meteorology in the 'Belfast Magazine' commenced in 1808. John Templeton studied birds extensively, collected shells, marine organisms : 403–413 403 -413 were. Much of his work was used by later authors, especially by William Thompson whose 'Natural History of Ireland' is its essential continuation.
