Joseph Charles Arthur (January 11, 1850 – April 30, 1942) was a pioneer American plant pathologist and mycologist best known for his work with the parasitic rust fungi (Pucciniales).

In his second year, botanist Charles E. Bessey obtained a professorship at Iowa State and it was under his guidance that Arthur began his formal study of botany.

To help facilitate Arthur’s studies, Bessey purchased a rust collection from the herbarium of Moses A. Curtis.

Underwood took Arthur to a pasture in the Bronx that was to become the future site of the New York Botanical Garden.

Arthur was elated by this news, as was the New York Agricultural Experiment Station where he was granted increased freedom to study rusts.

[8] The year after Arthur earned his Doctor of Science from Cornell in 1886, he was appointed professor of botany at Purdue University, where he remained until his retirement in 1915.

[9] It was at Purdue where Arthur began over 19 years of culture experiments with American species of rusts.

[10] He was faced with the task of identifying a species concept appropriate for rust fungi, many of which exhibit up to five different spore types and can alternate between two hosts, known as heteroecism.

Through those culture studies, Arthur realized the importance of host specialization to the delimitation of species.

Arthur also introduced a greater emphasis on morphological, and especially microscopic characters, such as the number and arrangement of germpores on spores that had up to this point, not been considered in the taxonomy of rust fungi.

This caused a standoff with Winthrop E. Stone, President of Purdue, who directed that he return all of the specimens, papers, drawings and notes related to his work with the North American flora to the herbarium.

Arthur married Emily Stiles Potter of Lafayette, Indiana in 1901 and the two lived together until her death in 1935.