Austrian botanist (Dutch-born) who collected plants in the West Indies for the imperial gardens of Schönbrunn. He spent the latter part of his life as a professor in Vienna. Born in Leiden to parents of French Catholic origin, Jacquin's cloth merchant father sent him to a Jesuit college in Antwerp. He returned to Leiden in 1744 to study medicine and botany, coming into contact with other botanists including J.F. Gronovius (1690-1762) and Laurens Theodoor (1730-1773). As well as his teacher, Adriaan van Royen, all were keen proponents of the novel Linnaean system.

Jacquin continued his medical training in Paris (1750-1752) and thence in Vienna on the recommendation of his friend Gerard van Swieten, professor of medicine at the University of Vienna. Swieten was physician to the Empress Maria Theresa and had advised on the planning of the gardens at Schönbrunn palace. Jacquin maintained a keen interest in botany while in Vienna, often visiting these gardens. Conservatories and hothouses were completed at Schönbrunn in 1754, at which point Swieten proposed that the emperor, Franz I, commission an expedition to collect tropical plants from the Caribbean. The emperor, acquainted with Jacquin, decided to send him on the mission, also requiring him to collect other 'curiosities' for the palace's natural history collections.

Accompanied by gardener Richard van der Schot and two bird collectors, Jacquin departed in 1755 and returned four years later with many rare plants, animals and minerals, drawings and descriptions. The party's itinerary took in St. Vincent, Grenada, Curaçao, Aruba, Venezuela, Colombia, Guadeloupe, St. Kitts, St. Eustatius, St. Maarten, St. Barthélemy, Santo Domingo (now Haiti and the Dominican Republic) and Cuba; the expedition was the first to ever bring home specimens from some of the smaller islands. Overall the trip was smooth, though one traveller died of dysentery on the way back to Vienna. Jacquin, too, suffered one serious bout of illness in 1758 which forced him to spend four months recuperating in Jamaica. After this he encountered a further difficulty when he was detained in Montserrat because of English-French hostilities. Nevertheless, he reached Vienna again in 1759. Though he did prepare some dried plant specimens, it is not thought Jacquin brought back sizeable collections of these as they are rarely found in European herbaria. Joseph Banks acquired some Jacquin material, but those sheets in the Banks herbarium at BM are only scrappy and few.

Upon his return to Europe, Jacquin published (perhaps hastily) a listing of his discoveries as Enumeratio Systematica Plantarum (1760), emphasising those plants he believed to be new to science. Linnaeus, who immediately entered into correspondence with Jacquin in 1759, greeted the work with enthusiasm. Three years later Jacquin published a more detailed description, the Selectarum stirpium americanarum historia, with drawings of many species. His names have been applied to many common plants of the Caribbean based on this work. He also found time to publish his first work on the flora of Austria in 1762, before moving to Schemnitz, Hungary (now Banská Štiavnica, Slovakia), where he was appointed to a professorship in chemistry and metallurgy. He spent nearly six years here, during which time he published further descriptions of his American plants and amendments to his Viennese flora. In 1769 he returned to Austria as the chair of botany and chemistry at the University of Vienna, remaining in this position until 1797. He also became director of the university's botanic gardens and supervised those at Schönbrunn. He published many more superbly illustrated botanical works in this period, including a monograph of the genus Oxalis (1794). He was made a baron in 1806.

Sources:
R.A. Howard, 1973, "The Enumeratio and Selectarum of Nicolaus von Jacquin", Journal of the Arnold Arboretum, 54: 435-436
R.A. Howard, 1975, "Modern Problems of the Years 1492-1800 in the Lesser Antilles", Annals of the Missouri Botanical Garden, 62(2): 370-371
F.A. Stafleu, 1971, "Jacquin and His American Plants", introduction to facsimile reprint of N.J. Jacquin, Selectarum stirpium americanarum historia: F7-F17.