Johannes Elias Teijsmann (June 1, 1808 – June 22, 1882) was a biologist, botanist and plant collector. He was born in Arnhem, The Netherlands. His surname is sometimes spelled Teysmann, although he himself spelled it Teijsmann.
Teijsmann travelled to Java in 1830 as gardener of Governor General Johannes van den Bosch. He was appointed the director - hortulanus - of the 's Lands Plantentuin in Buitenzorg (now Bogor) the following year, a post he held until 1869. He took part in important botanical expeditions throughout maritime Southeast Asia. Teijsmann was also part of a Dutch fact-finding mission to Siam (presently Thailand).
He is notable for the introduction of cassava plants (from the island of Bantam, near Sumatra) as a food source to alleviate famines in the then Dutch East Indies. Together with his collaborator Justus Carl Hasskarl, he introduced the cultivation of Cinchona trees (from Peru) for the production of quinine to treat malaria (ca. 1852/1854). There was bitter conflict between Teijsmann and two fellow botanists, Johann Eliza de Vrij (1813–1898) and Franz Wilhelm Junghuhn on the effectiveness of various Cinchona species in the treatment of malaria. Nevertheless, successful experimentation on the plant was carried out in the new Cibodas Gardens which eventually made Java the largest producer of kina (Cinchona bark). His personal interest in palm trees led Teijsmann to introduce the oil palm (from West Africa) to Indonesia, which remains a significant export earner for the country’s economy. He also introduced vanilla artificial pollination techniques to Java, making the crop much more productive and cheaper. Due to Teijsmann's hard put effort the number of plant collections in the garden had grown from 900 in 1822 to 10,000 in 1863.