Ferdinand Christian Gustav Arnold

Ferdinand Christian Gustav Arnold (1828–1901) was a German lichenologist and taxonomist born in Ansbach, Bavaria. Even as a high school student he showed an active interest in botany: "Ich und August Gattinger ... durchstreiften von November 1846 bis zum Spätherbst 1847, Pflanzen sammelnd, die Landschaft von München nach allen Richtungen." ("August Gattinger and I … roamed across the landscape of Munich from November 1846 up to the late autumn 1847, collecting plants, in all directions.").

He studied jurisprudence in Munich and Heidelberg and during his career practiced law in Eichstätt (1857–77) and Munich (1877–96). He was awarded an honorary doctorate by the University of Munich in 1878. Additionally he was a student of botanists Carl Friedrich Philipp von Martius (1794–1868) and Otto Sendtner (1813–1859), and his spare time was devoted to floristics and classification of plants and fungi.

His initial studies dealt with vascular plants, but his primary focus later shifted to lichens and bryophytes. Well known for his studies of herbarium specimens (exsiccatae), his personal herbarium contained approximately 150,000 specimens, largely consisting of lichens and lichenicolous fungi. Today this collection is kept at the Botanische Staatssammlung in Munich.

Arnold was the author of Lichenologische Ausflüge in Tirol (Lichenological Excursions in Tyrol), which is still considered to be an important source of information on alpine lichenology . He was a founding member of the Bayerische Botanische Gesellschaft, and in 1878 he received an honorary doctorate from the University of Munich. Arnold died in Munich in 1901. The journal series Arnoldia, named in his honor, started publication in 1991. It is devoted to describing the labels and annotations of the dried herbarium specimens in the Botanische Staatssammlung.

The standard author abbreviation Arnold is used to indicate this individual as the author when citing a botanical name.