The order Isoetales includes the modern "quillwort", the living genus, Isoetes with about 70 species, which has a worldwide distribution, and very similar fossils (Isoetites a mid-Cretaceous plant resembling modern Isoetes).  These are small, often aquatic plants with a short stem and elongate leaves.  These are highly reduced plants that have effectively "telescoped" the body into a small corm-like stem that lacks vegetative leaves (all the leaves are fertile sporophylls). Fossil forms are sometimes placed in the modern genus Isoetes. Like the more primitive Selaginellales, the Isoetales are heterosporous, producing two kinds of spore.