His special field of study was the Bromeliaceae on which family he was the recognized authority.
He was editor of the journal La Belgique Horticole in which he published descriptions of numerous new species.
His manuscripts and commissioned watercolor plates were sold to Kew Gardens by his widow shortly after his death and examined by John Gilbert Baker and Carl Christian Mez, who described numerous unpublished new species.
Baker made extensive use of these paintings in the preparation of his Handbook of the Bromeliaceae which was published in 1889.
Morren employed four artists to work on the plates - Marie Jean Guillaume Cambresier,[1] R. Sartorius, Francois Stroobant (1819-1916) and François De Tollenaere.