DILLEN (DILLENIus), JOHANN JAKOB English botanist, was born at Darmstadt and educated at the university of Giessen, where he printed in 1719 his Catalogus plantarum sponte circa Gissam nascentium. In 1721 he came to England, and in 1724 published a new edition of Ray's Synopsis stirpium Britannicarum. In i732 appeared Hortus Elthamensis, a catalogue of the rare plants growing at Eltham, Kent, for which Dillen himself executed 417 plates, and it was described by Linnaeus as opus botanicum quo absolutius mundus non vidit. In 1734 he became professor of botany at Oxford. Dillen, who wrote Historia muscorurn(1741), died at Oxford on April 2, For an account of his collections preserved at Oxford, see The Dil lenian Herbaria, by G. Claridge Druce (Oxford, 1907).