Black Acacia is a tree that can be found in parking strips in older neighborhoods around San Diego. I once had an old one in front of a house I owned at the time. It was felled by the city because it was causing problems with the sidewalk. The wood is incredibly tight grained and fibrous and nearly as hard as ironwood. I never thought of it as luthier material, but I can see the possibilities. I wonder if Bob Taylor has ever considered it.