Other forms not as purple as 'Purpurea'. The diameter of the individual flowers would indicate whether it was the hybrid catalpa or the southern catalpa. The latter also produces leaves that are more hairy beneath than the hybrid. Since the flowers look big and close together the one shown here may be southern catalpa. Being a grex hybrid catalpa varies but the common pattern is for the flower heads to have more gaps than with southern. Since the ones shown here are not larger, more developed heads it is not possible to see what the biggest heads are like on this tree. Northern catalpa produces a smaller number of flowers in each head and earlier in the year than southern catalpa. I'd expect northern catalpa to have a more truss-like inflorescence and be done blooming by now.