Eugen Otto Wilhelm Ruhland (7 August 1878 – January 5, 1960) was a German botanist and plant physiologist.
He served as a professor of botany at the universities of Tübingen and Erlangen.
Ruhland was born in Schleswig where his father was a government official.
Along with Hans Winkler he founded and edited the journal Planta from 1925.
In 1933 he was a signatory to the Vow of allegiance of the Professors of the German Universities and High-Schools to Adolf Hitler and the National Socialistic State.