[Sue@lagouraxi]

Does anyone know the Greek name for this stunning tree flowering now - known in English as Manna ash - resin previously used as a sweetener?

[Andriy]

Dear Sue!
Take a look here http://mediplantepirus.med.uoi.gr/pharmacology/plant_details.php?id=123.
The greek name for a Fraxinus genus is "Φράξινος". The names "Μελιός", "Μέλεγος", "Φράξο" may also be used.
The exact name of a tree you are asking about is "Φράξινος ο όρνος".