Good name, Cow Itch - I haven't heard it called that before. It is commonly planted in coastal towns because of its salt tolerance, and then it somehow gets out into swampy areas mostly. I don't know how, since the seeds don't look particularly enticing and the fibreglass-like stuff they are embedded in would be a definite turn-off for birds you'd think. But it's a fairly common weedy tree on the south coast.
Thanks Jackie. There were Little Wattlebirds feeding in the tree and they didn't seem at all bothered by the seed heads. I picked up a seed head one day as a kid and got the needle like spines all across my palm. Swelled up red and hurt more than any wasp or bee sting since. Tweezers to get them all out! They used to use them as street trees in Wodonga Victoria until too many encounters with people/pets and then they were all removed!