The long things sticking out fling the seeds away, so you have to catch them just before they get flung. They are inside the catapult heads and look like brown (pale or dark) ovals, usually with some kind of a "seam" going down the length, one per "head" (and about the size of the head). You usually can tell when they are about to go when the "head" starts to detach from the base, although you do have to look closely.

You lost me. I had the same question about the seeds--I'm not finding them. If I cover the fading flower head with a tulle drawstring bag, do you think it will catch them when they get 'flung'?

I pull off the brown "sword" when it gives way with a gentle tug. Then I take the fat end and pick the seeds loose, usually 4 or 5 of them. They have a sort of "feather" they use for flying that stays attached. I have winter sown many of these and they come up just great but grow slowly. The ivy geraniums grow very well this way and the danged bud worms don't attack them like they do the standard geraniums. I winter them over in my garage and bring them back out in the spring and have geraniums that perk up and grow beautifully. Does this help at all?
Tina