Ellis was born in Potsdam, New York, on January 21, 1829, to parents Freeman Ellis and Sarah Bicknell. He was the tenth child of fourteen. In 1851, he graduated from Union College in Schenectady, New York, the same institution attended by lichenologist Edward Tuckerman (A.B. 1837) and mycologist Charles Horton Peck (A.B. 1859). Bicknell began an erratic career as a classics teacher and farmer in New York, Pennsylvania, and South Carolina. He became the principal of the Canton Academy in 1856, the same year he married Arvilla Jane Bacon, who became his lifelong assistant and collaborator. Their daughter Cora was born on January 12, 1857; she later became a professional musician in New York. It was around this time that Bicknell started developing his interest in botany, by collecting plants with fellow teachers on weekends. He saw a copy of Henry William Ravenel's Fungi Caroliniani Exsiccati, a set of dried specimens (exsiccata) collected and distributed from North Carolina and area. Ellis initiated a correspondence with Ravenel, and established a friendship that lasted until Ravenel's death in 1887.^[1]

Ellis taught in a public school in Potsdam village in 1863,^[2] and later served on the Union side in the American Civil War from 1864 to 1865.^[3] He served on the steam frigate USS Susquehanna of the North Atlantic Blockading Squadron, and was present during the bombardment of Fort Fisher on December 24–25, 1864 and January 13–15, 1865, when the Fort was captured. The war took its toll on his spirits; his April 22, 1865, diary entry reads: "I have felt degraded ever since I have been here & no amount of money & I might perhaps safely say no motive not even patriotism will ever induce me to put myself in the like position again."^[1] He was discharged from the Navy on May 18, 1865, and returned to Potsdam.^[1] After the war Ellis settled in Newfield, New Jersey, where he lived until his death.^[2]

Although he did not have any formal training as a botanist or mycologist, Ellis gradually took up mycological fieldwork and ultimately dedicated his life to the collection and exchange of dried fungal specimens. He created four exsiccata series as reference collections that were sold in sets of one hundred, or "centuries".^[4] The most important of these were the Fungi Nova-Caesarienses (Fungi of New Jersey) (1878) and the North American Fungi, issued in Series I and Series II from 1878 to 1898.^[2][5] The complete set of North American Fungi numbered 3600 specimens.^[6][7] The obituary of his wife, who died on July 18, 1899, elaborated her devotion to his work:

Besides binding many of her husband's books and pamphlets, she prepared some three thousand blank books in which the North American Fungi were issued and in which the greater part of the Ellis collection was mounted. Besides this she arranged at least three fourths of the 200,000 specimens which were issued in this exsiccata series and in the Fungi Columbiani^[8], folding papers, inserting specimens, pasting labels and inserting in their places.^[9]

Based in Newfield, New Jersey, Ellis maintained an extensive correspondence with many renowned American and European mycologists. In 1880, Ellis began to receive financial support from Benjamin Matlock Everhart, a wealthy merchant of West Chester, Pennsylvania. Together they co-authored North American Pyrenomycetes (1892). With William A. Kellerman, Ellis and Everhart founded the Journal of Mycology in 1885, a forerunner to Mycologia. Most of the articles in the first issues were written by Ellis. He published many of his newly discovered species in the journal, as well as the Botanical Gazette, Torrey Bulletin, American Naturalist, and Proceedings of the Philadelphia Academy. In 1896, near the end of his life, Ellis sold his collection of over 100,000 specimens to the New York Botanical Garden for its Cryptogamic Herbarium, including the types of 4,000 new species described by Ellis and his collaborators.^[11] The Garden Library also received a "large cache" of his letters in 1983.^[12] Ellis was one of the most prolific authors of new fungal species, having formally described about 3520 in his career.^[13] He was also a prolific author, and published over 500 scientific articles. He died December 30, 1905, in Newfield.^[2]

Ellis was honored by several scientific societies. In 1878, he was elected a corresponding member of Philadelphia's Academy of Natural Sciences. In August 1882 he was elected a corresponding member of the Cryptogamic Society of Scotland and in December of the same year was elected a corresponding member of "Die Kaiserlich-Königliche Zoologisch-Botanische Gesellschaft in Wien".^[2]

• Works by or about Job Bicknell Ellis at Internet Archive