Recently an aquatic fern called Hydropteris has appeared that seems to be an intermediate between these two orders of water ferns, which had traditionally been thought to come from separate lineages out of the filicaleans. Cycads typically have short, stout trunks, although their stems can also be tuberous, more elongate or even rhizomatous. Stems have manoxylic wood and resin canals and girdling leaf traces, a feature that is unique to this group. They have pinnately compound leaves with either single veins, simple dichotomous or rarely reticulate venation. They are dioecious with individuals bearing either pollen or seed cones.
Cones can get to be very large.
Pollen is borne in sacs on lower surfaces of the microsporophylls in pollen cones and is nonsaccate and monolete. When it germinates it produces a branched, haustorial pollen tube and swimming sperm. Ovules are borne pinnately on megasporophylls with their micropyles pointed out. Usually the megasporophylls are aggregated together in to a cone, although some species of Cycas have unaggregated, more leafy megasporophylls. Similarities in ovule size and structure and some other features have suggested to some that cycads might be related to medullosan seed ferns.