Thanks. I think you are probably right. The plant doesn't grow more than 12' - 15' in my garden and has soft needles on the branches. Very tough plant !
There are about 10 species of Robinia. Of the more familiar ones this would be R. hispida. R. pseudoacacia is a tall shrub or tree with white flowers. R. Purple Robe(TM) PP 2454 is from an intentional crossing of R. x ambigua 'Decaisneana' and R. hispida 'Monument' made by W. Silva in California. Another common purplish flowered, treelike hybrid locust is R. x ambigua 'Idahoensis'. Both of these have R. pseudoacacia in their genes via the R. x ambigua (R. pseudoacacia x R. viscosa) parent, but neither are pure R. pseudoacacia and should never be listed as such.
