Moss spores. Coloured Scanning Electron Micrograph (SEM) of 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. The bright yellow spores are the asexual reproductive cells of L. clavatum, and are ripe between June & September. The stag's-horn clubmoss is found today on mountain moors, heaths and grasslands. Lycopod mosses were widespread during the Carboniferous period (345-280 million years ago). Magnification: x250 at 6x6cm size.