Crossland initially became interested in
botany in 1880, whilst helping one of his daughters with a Sunday school wild flower project. He joined the
Halifax Scientific Society to pursue his new-found enthusiasm, and subsequently the
Yorkshire Naturalists' Union. In 1888, at a
YNU fungus foray, Crossland met
George Edward Massee who encouraged him to take an interest in
fungi. As a result, he developed an expertise in
mycology, with a particular interest in the
discomycetes, making extensive local collections, often in the company of Henry Thomas Soppitt and fellow mycologist and
bryologist James Needham. Crossland produced many papers on Yorkshire fungi, including several describing species new to science. His two major works were the cryptogamic section of the
Flora of the parish of Halifax, jointly authored with botanist W.B. Crump in 1904, and
The Fungus Flora of Yorkshire, a substantial volume co-authored with Massee, in 1905. His collections of fungi, drawings, and notes are now in the mycological herbarium at the
Royal Botanic Gardens, Kew. Charles Crossland became the first secretary of the Yorkshire Naturalists' Union
Mycological Committee in 1892, becoming president of the union itself in 1907. He was a founder member of the
British Mycological Society, becoming its first treasurer in 1896. He was made a fellow of the
Linnean Society in 1899. ==Taxa==