Roots absent; stems bearing reduced, unveined or single-veined euphylls; sporangia large, with walls two cells thick, lacking an annulus; two or three sporangia fused to form a synangium, seemingly borne on the adaxial side of a forked leaf; spores reniform, monolete, many (>1000) per sporangium; gametophytes subterranean (Psilotum), non-photosynthetic, mycorrhizal; x = 52
