Clubmoss (Selaginella selaginoides) strobilus. Light micrograph of a section through a strobilus from a lesser clubmoss plant, showing the sporophylls (leaves) and male microspores (brown). Sporophylls are leaves that bear sporangia, where spores are produced. Strobili are structures that consist of sporangia-bearing structures densely collected along a stem. Magnification: x5 when printed 10 centimetres wide.