Comment on sporophyte of Marattiales.
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The Marattiaceae are a distinct group of (almost always) terrestrial ferns with large, fleshy, erect or creeping rhizomes, with a polycyclic dictyostele (Sporne 1962, Smith et al. 2006), and mucilage canals in the roots, rhizomes and leaves. Young plants usually contain a mycorrhizal fungus - the oomycete Stigeosporium marattiacearum C. West - within the cortex (Sporne 1962). Other notable features are the starchy, leathery or papery stipule-like paired auricles at the base of each petiole, which are unique among ferns. Many species produce proliferous buds on the stipules or on the leaves (Uffelen 1994). The leaves are generally large and leathery (except in some “filmy” Danaea), and 1-3-pinnate (simple in some Danaea, or palmate in Christensenia). The petioles and rachises have polycyclic xylem and swollen pulvinae at the base of each internode. The sporangia are usually fused in round or elongate synangia, where a thin part of the sporangium dries and shrinks to form a pore through which the spores fall, except in Angiopteris where the sporangia are almost free. Each sporangium encloses very large numbers of spores (from about 1000 in Angiopteris to 7000 in Christensenia); these are usually monolete, bilateral or ellipsoid, and echinate (Sporne 1962, Smith et al.