I don't know either... but about this time of year, the underside of the fronds get covered with this pollen looking stuff. I thought I'd show you since yours won't have any fronds on when you get them. These fronds will turn brown and die in spring. For garden tidiness, I usually cut them off about now, before the new ones come up. To propogate them, you might want to leave them until they die.
I've only ever really multiplied them by digging them up and splitting them, so I really don't know. They're looking a little more dignified now, I put them in buckets.
And now I'll take a break from the pictures for awhile, so the dial up folks don't curse my name [any more than they already are] :~D