First, the pics. These two were taken by a Gardenwebber, Peter_NZ, while visiting New Caledonia (be patient - the server can be slow):
http://www.kakariki.orcon.net.nz/Xeronema2.jpg
http://www.kakariki.orcon.net.nz/Xeronema1.jpg
He said it was at: "Monts Koghis, south-western Grande Terre, New Caledonia, March 2002". I find it rather odd that it was in March (autumn), as X. callistemon blooms in the spring.

Here's some more pics, taken in October (spring) in New Caledonia:
http://www.endemia.nc/plante/fiche.php?code=116
Notice how small they can start flowering at.

I emailed a professor in NZ named John Dawson, who had mentioned the species in an article, and he had this to say:

"X. moorei is quite common on rocky mountain ridges, mostly ultramafic but also schist in the north-east. I have seen X. moorei a number of times and it seems to flower at various dates bur this isn't uncommon in the tropics. It is a smaller species with shorter leaves, smaller inforescences and shorter flower heads. It is perhaps a brighter red too. Hybrids between the two could be interesting."

By the way, "ultramafic" rock is very high in iron and magnesium - so much so that most plants can't grow in it. I think X. callistemon grows in a more normal composition of rock (volcanic).

Somewhere here i have a photocopy of the journal Pacific Science, vol. 11, 1957, which gives a botanical comparison of the two species, and explains the "bracteosa" variety. If you don't have access to this, let me know and i'll dig it up.
Maybe we can trade notes on X. callistemon through email?

Before making a comment, are you the same Cherimoya that contributes to the craigslist.org (SFO) gardening forum? Prob. not, but just curious . . .

In any event, and with all due respect, you are mistaken about plants growing in the ultramafic soils in NC. Very large areas of NC are exclusively ultramafic (which also includes high nickel values as well as chromium and other fairly toxic elements), and these regions have an incredible and stupefyingly diverse and varied flora growing on it.

X. moorei does, from what I've heard, grow in ultramaffic environments (as well as others). If you are interested in more information, I may be able to tell you where to go.