Family: Loranthaceae (Mistletoe family).
It is common in the Harcourt-Faraday area where it grows on Red Gums. It is abundant along the old Calder Highway in the vicinity of the vineyards.
Creeping Mistletoe has a wide range of hosts, including introduced trees, such as the Plane Trees in Collins Street and St Kilda Road. I have not seen it on anything but Red Gums locally.