there are multiple species of Ash that grow here in North America. Common names include Northern Ash, Black Ash, Green Ash, Pumplin Ash, etc ... There is no species with the common name of Swamp Ash. without specific scientific testing together with a sample of the bark and leaves, it is extremely difficult to know the precise species of Ash you are purchasing from a wood supplier
in the guitar wood industry, Swamp Ash is a marketing term for 'light weight' Ash and is typically wood from several of the different Ash species
furniture makes want wood of a consistent heavy density, as this has the best properties for their needs. they pay more for the heavier graded wood, guaranteeing them thay they won't be spending money on 'punk Ash' that is unusable
guitar builders want wood of a consistent maximum density where lighter is better, as this is a feature that their customers demand. they pay more for the lighter graded wood, guaranteeing them that they won't be spending money on 'Northern Ash' that is too heavy for what their customers demand
the wood companies sell to both industries what their market demands, and sort specific to the needs of each market
instrument makes answer to their customers ... and because customers are always right (even if they are quite uninformed at times) ... Swamp Ash rules for guitar body making
all the best,
R