One after another, musicians added their names to the list at Inman Square’s 1369 Jazz Club, waiting for a turn to trade wailing solos at the blues jam that Silas Hubbard Jr. led each Sunday afternoon beginning in the mid-1980s.

“It should be fun, not an ego trip,’’ he told the Globe in 1993, when the jam had migrated to the Black Rose in Harvard Square. “You’ve got to let people express themselves.’’

A blues singer proficient on harmonica and bass, Mr. Hubbard hosted what many considered Boston’s first honest-to-goodness blues jam at the 1369 club in Cambridge. After it closed, he moved the jam to another venue, then another, as other area club owners and musicians caught on and copied his approach.

“It’s like a bud that you plant, and it comes up in the spring,’’ he said with a smile about the blues jam circuit that grew from what he started. “It seems like a lot of buds have sprung up.’’

Mr. Hubbard, who was still playing area clubs until a month ago, died of pneumonia April 7 in Massachusetts General Hospital. He was 63 and lived in Boston.

During his career, Mr. Hubbard and his band opened for such luminaries as Ray Charles and the Four Tops. Blues jams he began with help from his late brother, Earring George Mayweather, a blues harmonica player, helped launch the careers of area artists Annie Raines, Chance Gardner, and Eric “Two Scoops’’ Moore.

“It’s like a blues church to me,’’ Moore, a pianist, said of the 1369 club in a 1986 interview with the Globe. “And Silas Hubbard is the priest.’’

When the club closed in 1988, Mr. Hubbard just “moved around the corner and continued playing the blues,’’ said bass player Gary Barcus.

“Silas was indefatigable,’’ he added. “He always looked on the optimistic side and figured that there was always someplace else to go, someplace else to play, a new hook-up.’’