Harry Delbert Thiers (January 22, 1919 in Fort McKavett, Texas – August 8, 2000 in Ohio) was an American mycologist who studied and named many fungi native to North America, particularly California. Thiers taught mycology at San Francisco State University. He comprehensively revised and expanded on the North American collection of boletes and named many new species. Species authored by Thiers include the boletes Suillellus amygdalinus, Boletus barrowsii, Xerocomellus dryophilus, Rubroboletus pulcherrimus, Leccinum manzanitae, and other mushrooms including Gymnopilus luteoviridis and Russula xanthoporphyrea.

Legacy

The fungal genera of Chaetothiersia and Harrya and the species of Cortinarius thiersii were named in his honor. Botanist and herbarium curator Barbara M. Thiers is his daughter.

Harry D. Thiers Herbarium

San Francisco State University (SFSU) established the herbarium in 1959 with the name the "San Francisco State University Herbarium". When Thiers retired in 1989 the herbarium was given its present name. Thiers and his students collected most of the early specimens. Later, Dennis E. Desjardin and his students made major contributions. The herbarium has taxonomic coverage of fleshy fungi, lichens, bryophytes, and vascular plants. Specimens were collected from North America (especially California), South America, the Hawaiian Islands, Indonesia, southeast Asia, Micronesia, and Madagascar.