Solid white pine. The posts are 5x5 with pegged through-tenons on the half-notched stretchers. This glass top is a 4' x 6' oval and a full 1" thick making it extremely heavy.  The key to making this base sturdy enough to hold the glass is tight locking joinery. Not using fasteners or glue makes the base able to knock down completely. The white pine comes from trees planted by my father some 40 years ago and recently harvested after a bad storm.