He would remain with the department until his death, succeeding to George Vasey as Chief botanist in 1893, a title accompanied with that of Honorary Curator of the National Herbarium (at the time conserved at the Smithsonian Institution, but funded by the USDA).

A tall man who had enjoyed success in college sports, he was described as helpful, perceptive, clear-thinking and curious, as well as greatly enthusiastic in his outdoor expeditions.

[1] In 1911, he began a program of research in conjunction with Elizabeth White, daughter of the owner of the extensive cranberry bogs at Whitesbog in the New Jersey Pine Barrens.

His work doubled the size of some strains' fruit, and by 1916, he had succeeded in cultivating blueberries, making them a valuable crop in the Northeastern United States.

In 1919, Coville played an instrumental role in drawing attention to the threatened state of the only known box huckleberry colony,[3] sparking a revival of interest that led to the discovery of many new specimens of the plant.