Update 19/11/16: more recent photos of Nuytsia floribunda
A decade ago I had a boyfriend who lived in Kalamunda, an outer suburb of Perth. It’s on the Darling Scarp, the hills to the east of Perth, and as Christmas approached, the orange flowers of Nuytsia floribunda were a beautiful sight on my drive there. They’re called Christmas trees for the timing of their flowering, but anytime I talk about these Christmas trees people get confused with the Christmas trees people decorate right about now. Western Australian Christmas trees are so much better, because they decorate themselves.
Five years ago I worked in Kelmscott, south of Kalamunda, at the foothills of the Darling Scarp. My drive there was more enjoyable towards the end of the year because of the copious orange flowers of the Christmas trees. These days I don’t drive so far and the only Christmas tree I see regularly is at the front of a house near where I live (left). Whether I’m driving or catching the bus I go past it and it’s looking magnificent right now. An older woman lives in the house and when such people move on, the house is often sold and demolished for subdivision. I hope if this happens the Christmas tree will not be cleared.
There’s a lot of land clearing in Perth these days as our suburbs sprawl further and further (and our flora and fauna suffers ). My friends at Nuts about Natives have their nursery in a semi-rural outer suburb of Perth and a freeway is being extended next to their land. This area was previously grazed by kangaroos and cattle (and terrorized by dirt bike riders) and its vegetation included paperbarks (Melaleuca) and Nuytsia floribunda. When the vegetation was being cleared Ben told me I should come down and get one of the Nuytsias. I could have borrowed a trailer from my dad, but I never got around to it, partly because I don’t really have the room for another tree after planting the tuart and a hakea.
There are a few Christmas trees at Curtin University where I study. Much of their landscaping involves indigenous plants, which makes for some beautiful grounds. My dad told me he saw Christmas trees flowering at Star Swamp when he rode past. The header photo is of Nuytsia floribunda flowering at Star Swamp.
Nuytsia floribunda are parasitic through their roots on other trees, like that other parasitic Christmas plant, mistletoe. Nuytsia often grow next to another tree in order to parasitize it, but they can survive by only parasitizing nearby grasses or trees up to 150m away . Other mistletoes are
air-born parasitic plants which live off the sap of their hosts. 
I always thought the only other mistletoes were European (Viscum album) and North American (Phoradendron serotinum), but there are about 90 Australian species . They can infest trees in plague proportions in some parts of Australia. Mistletoe is ten times more abundant in south-east Australia than before European settlement . Ecologist Dr David Watson investigates mistletoes worldwide and his research in Australia
suggests that mistletoe, far from being an environmental scourge, plays a central role in maintaining ecosystems. 
Mistletoe provides food and shelter for many native birds and mammals. The NSW North West Weeds group suggests installing nesting boxes in trees to attract native birds and mammals if you have a mistletoe problem on your land . Dr Watson believes,
mistletoe infestations are a symptom, not a cause of a much bigger problem. Changes in fire frequency and intensity, clearing trees and a reduction in native animals have all contributed.