UNITY ? A total of 104 graduates at Unity College, clad in black caps and gowns, walked off the commencement stage Saturday with a degree clasped in one hand and a tree seedling cradled in the other.

The seedling tradition at “America’s Environmental College” was started many years ago by longtime botany professor Martin Rosinski, who died in 1988.

This year, graduates chose Jimmy Hubbard, a 25-year custodian at the college and a trusted friend, to carry out the seedling custom.

All majors studied at Unity College are environmental in nature, Mark Tardif, associate director of College Communications, said Saturday, noting Unity College celebrates its 40th anniversary in September.

Commencement speaker Naomi Schalit, executive director of Maine Rivers in Augusta, spoke to graduates about being activists for the environment.

“Being an activist means having the imagination to speak the truth to power,” Schalit said. “There is no more fundamental truth about activism than this.

“You must be able to imagine a better, more just world in order to fight for it and then speak about it. And fighting for truth and fairness against powerful, entrenched forces means not knowing what the response will be ? walking, essentially, into the unknown, which is a frightening place.

“But it is a place you must enter in order to find the new, the right and the just.”

Of the 104 graduates at the 525-student college, 100 were awarded bachelor’s degrees, and four received associate degrees, in environmental studies.

A reception on the lawn outside Quimby Library followed the commencement.