A plant with a place in photographic history

The stag's horn clubmoss Lycopodium clavatum is an ancient  spore-bearing vascular plant. These are the "cones" which produce the spores in July-August.
In the past the spores were used as a dusting agent on latex condoms. They are also highly inflammable and were once used in fireworks where they burn explosively emitting sparks and in photographic flash powders. Their lightness and propensity to stick to any slight electrical charge or oil also made then useful as a fingerprint powder.