István Isépy, Hungarian botanist and vegetation ecologist passed away on 8 November 2022 at the age of 80. From a young age, learning about the flora became the focus of his interest, so after completing high school, he applied for the biology-chemistry teacher training program at the Eötvös Loránd University (ELTE), Budapest, where he earned his degree 1966. After graduating from university, he received a job in the research group of the Hungarian Academy of Sciences operating in the ELTE Botanical Garden, and from 1982 until his retirement in 2005, he worked as the director of the ELTE Botanical Garden. In his scientific research, he investigated the forest associations of the Vértes Mountains (Western Hungary), the turnover of organic matter in oak-hornbeam forest ecosystems, the ecology of dry grasslands of the Pannonicum, and the possibilities of ex situ conservation and propagation of protected plant species. In addition, he participated in the flora and vegetation mapping of Hungary, and had an active role in the establishment of nature conservation areas. As a university lecturer, he mainly taught plant systematics and biogeography. In addition, his elective courses on botanical garden plant diversity in every spring and autumn, as well as the optional high mountain field trips organized during the summer vacation, were popular among the students. He led botanical expeditions to Uzbekistan, Georgia, Austria, Slovenia, Italy, and Transylvania. His excellent work was acknowledged by several awards, including the civilian section of the Knight's Cross of the Hungarian Order of Merit and the József Gelei lifetime achievement award of the Hungarian Biological Society. He will always be missed as a kind and helpful person who wanted to do something for the science of botany and its popularization. We honour his memory in the pantheon of Hungarian botanists and directors of the ELTE Botanical Garden. [ABSTRACT FROM AUTHOR]