Coloured scanning electron micrograph (SEM) of two spores from a stag's-horn clubmoss (Lycopodium clavatum). These spores were once collected as lycopodium powder and used for photography flashes and as a moisture-absorbing skin powder. Spores are the asexual reproductive cells of a clubmoss plant. The stag's-horn clubmoss is found on mountain moors, heaths and grasslands. Lycopod mosses were widespread during the Carboniferous period (345-280 million years ago). Magnification: x1,700 when printed at 15cm wide.