Doors member Krieger sings while touring Washington

Robby Krieger, guitarist and founding member of the Doors, was in a musical mood as he took a tour of the U.S. Botanic Garden on Monday, ahead of his concert with Ray Manzarek at the Birchmere in Alexandria, Va.

While taking in D.C. with friend and former House Administration Committee staffer Richard Landon and another pal, old blues tunes kept coming to mind for Krieger.

When he spotted some cotton balls at the Capitol Hill greenery mecca, the “Light My Fire” writer started crooning “Cotton Fields,” by blues godfather Huddie “Lead Belly” Ledbetter. Krieger, 66, then saw a bird, and started belting out a Lonnie Donegan number about the flying animals.

We hear Krieger, who knows his stuff when it comes to horticulture and had an uncle who was a botanist, was particularly fascinated by the medicinal plants and the chocolate-producing cacao tree.