Roscher (Nektar and Ambrosia, 1883; see also his article in Roscher's Lexikon der Mythologic) nectar and ambrosia were originally only different forms of the same substance - honey, regarded as a dew, like manna, fallen from heaven, which was used both as food and drink.
Xvi.) P's version of the sending of the manna and quails.
The manna ash is a small tree found in Italy, and extending to Switzerland, South Tirol, Hungary, Greece, Turkey and Asia Minor.
This kind of manna seems to be alluded to by Herodotus (vii.