Joseph Decaisne was a French botanist and agronomist.
He became an aide-naturaliste to Adrien-Henri de Jussieu, who served as the chair of rural botany. It was during this time that he began to study plants brought back by various travelers like those of Victor Jacquemont from Asia.
Dacaisne used applied research, most notably on the agronomy of the madder, the yam and the ramie. He was also interested in algae.