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Bennettitales is an extinct group of seed plants with reproductive structures that are similar in some respects to both Gnetales and angiosperms, but systematic relationships among the three clades remain controversial. This study summarizes characters of bennettitalean plants and presents new evidence for the structure of cones and seeds that help clarify relationships of Bennettitales to flowering plants, Gnetales, and other potential angiosperm sister groups. Bennettitales have simple mono‐ or bisporangiate cones. Seeds are borne terminally on sporophylls. They have a unique structure that includes a nucellus with a solid apex, no pollen chamber, and a single integument, and they are clearly not enclosed by a cupule or other specialized structures. Such features differ substantially from Gnetales, flowering plants, and the seed fern Caytonia, providing no compelling evidence for the origin of the angiospermous …