From 1836 to 1862 he performed extensive botanical research throughout the Middle East and northern Africa, in which he collected over 300,000 botanical specimens. Beginning in 1836, he accompanied geologistJoseph Russegger (1802–1863) on a scientific trip to Cilicia and Syria, afterwards journeying through Nubia and Sennar. Following the dissolution with Russegger's expedition, he remained in Egypt. He later traveled to Kurdufan (1839), Cyprus, Syria, Mesopotamia and Kurdistan (1840–41); and during 1842–43 he undertook an expedition to Persia. Later he performed botanical investigations in Egypt, Palestine and Lebanon (1855); and also in Cyprus, Asia Minor and Kurdistan (1859). In 1862 he performed additional botanical research in Cyprus and Syria.
Abbildungen und Beschreibungen neuer und seltener Thiere und Pflanzen, in Syrien und im westlichen Taurus gesammelt, (Illustrations and descriptions of new and rare animals and plants, in Syria and western Taurus); (1843)