American botanist interested in the flora of Minnesota. Originally from Hillsdale in Michigan it is not certain where Conway MacMillan was first educated, but he later moved to Lincoln and the University of Nebraska, graduating from there with a BA in 1885. After receiving an MA the following year he began to work as an assistant geologist on the university's Board of Regents and also undertook an expedition to the Badlands of South Dakota with Prof S.E. Hicks. For a short while MacMillan worked as an entomologist at the Nebraska Agricultural Experiment Station before leaving the state in 1888 when appointed instructor of botany at the University of Minnesota. By 1893 he was a full professor there and was known for his excellent teaching ability.

His research centred on the flora of Minnesota and plant ecology. Also working as a botanist for the Minnesota Geological Survey and the Natural History Survey he published two important works on the flora of this state: his Metaspermae of the Minnesota Valley (1892) and Minnesota Plant Life (1899). The latter of these was a particularly important and well written ecological contribution to the flora of the USA. During his final five years at the university (1901-1906) MacMillan served as director of the Minnesota Seaside Station, a laboratory which he had established to aid the study of marine plant and animal life. On retiring in 1906 he moved to Philadelphia where he became involved in the advertising industry.

Sources:
H.B. Humphrey, 1961, The Makers of North American Botany: 159-160
F.A. Stafleu and R.S. Cowan, 1976-1998, Taxonomic Literature, 2nd edition (TL-2).