He started his career as an apprentice to his grandfather, the publisher of the Oquawka Spectator newspaper.
At the age of 19, he published his first botanical paper, which was a catalog of plants collected around his hometown of Oquawka, Illinois.
He began to study the flora of Colorado sporadically between 1880 and 1895, with his early trips focused on the Gore Range.
He often collaborated with botanists such as Michael Schuck Bebb, Cyrus Pringle, Edward Lee Greene, William Marriott Canby, and Asa Gray, and exchanged printed floras with his contemporaries.
He also published works by other botanists, including John Donnell Smith's catalog of Guatemalan plants.