Thank you for starting this thread, Hilary, and so nice to see that it has generated so much interest as far away as Australia!
I was also intrigued by the reference to Menelaus having married into a tree-cult.
It seems there were a number of cults of Helen (Helen of Troy, wife of Menelaus, daughter of Zeus and Leda, sister of Castor, Polydeuces (Pollux) and Clytemnestra).
There was a cult of Helen and Menelaus at the Menelaion in Therapne (near Sparta), focusing on Helen as a married mortal woman (in spite of its name, this was originally a shrine to Helen alone) and a cult of Helen Platanistas (Helen of the plane trees) focusing on Helen as a divine virgin figure associated with fertility through tree worship.
Helen was also worshipped in Attica along with her brothers and in Rhodes as Helen Dendritis (Helen of the trees).
For more information see:
http://argos.chs.harvard.edu/cgi-bin/WebObjects/eJournal.woa/wa/dist?dis=159#n.5