The willow oak (Quercus phellos) is a state-endangered species in Pennsylvania (rank S2). It occurs rather abundantly in the tiny sliver of the Atlantic coastal plain that stretches into the very southeastern corner of PA. But because most of this coastal plain region in PA has been developed, fragmented, or otherwise extensively disturbed, their wild populations are relatively low in number. Willow oak does quite well as a street and landscape tree here in Philadelphia and suburbs (even into th