I did some reading, and the three-leaf arrangement is called "whorled." However, it alternates by 60 degrees (or 180 - could be either way) at each leaf level, making it also "decussate."
I've googled pictures and seen this elsewhere, so it's apparently not that rare - but none of them are this big!
The stems of these are now huge - about 1/2 inch thick! The flower heads are also huge. They are even growing stems in three directions from the leaf/stem joints at the lower levels now with their own flower heads. The leaves are also larger, which probably is why the stem is more than the expected 50% larger size.
It's a monster! I'll be posting pictures with a ruler for showing size in the next few weeks.
