Bernard Mathew Leadon III (pronounced led-un; born July 19, 1947) is an American musician and songwriter, best known as a founding member of the Eagles. Prior to the Eagles, he was a member of three pioneering and highly influential country rock bands: Hearts & Flowers, Dillard & Clark, and the Flying Burrito Brothers. He is a multi-instrumentalist (guitar, banjo, mandolin, steel guitar, dobro) coming from a bluegrass background. He introduced elements of this music to a mainstream audience during his tenure with the Eagles.

Leadon was born in Minneapolis, one of ten siblings, to Dr. Bernard Leadon Jr. and Ann Teresa (nee Sweetser) Leadon, devout Roman Catholics. His father was an aerospace engineer and nuclear physicist whose career moved the family around the U.S. The family enjoyed music and, at an early age, Bernie developed an interest in folk and bluegrass music. He eventually mastered the 5-string banjo, mandolin and acoustic guitar.  As a young teen he moved with his family to San Diego, where he met fellow musicians Ed Douglas and Larry Murray of the local bluegrass outfit, the Scottsville Squirrel Barkers. The Barkers proved a breeding ground for future California country rock talent, including shy, 18-year-old mandolin player Chris Hillman, with whom Leadon maintained a lifelong friendship. Augmented by banjo player (and future Flying Burrito Brother) Kenny Wertz, the Squirrel Barkers eventually asked Leadon to join the group, upon Wertz's joining the Air Force in 1963.  His stint in the Scottsville Squirrel Barkers did not last long. In late 1963, his family once again relocated to Gainesville, Florida, when his father accepted a position as Professor of Aerospace Engineering at the University of Florida. Leadon attended Gainesville High School, where he met classmate and future Eagles lead guitarist Don Felder, whose band, the Continentals, had just lost guitarist Stephen Stills. Upon Leadon's joining the group, rechristened Maundy Quintet, they gigged locally, even sharing the bill with future Gainesville legend Tom Petty and his early band the Epics (a band that also included Bernie's brother, musician Tom Leadon).  A call from ex-Squirrel Barker Larry Murray in 1967, to join his fledgling psychedelic country-folk group, Hearts & Flowers, was enticing enough for Leadon to return to California, where he soon became involved with the burgeoning L.A. folk/country rock scene. Leadon recorded one album with the band, their second release Of Horses, Kids, and Forgotten Women for Capitol Records. The record was a local hit but failed to make much of a dent on the national album charts. Discouraged, the group disbanded the following year. Answer this question using a quote from the following article:

What instrument did he play in that band ?
banjo