The Nilssoniales were a bizarre and entirely extinct group of Mesozoic plants with cycad-like leaves. Although they are often tentatively grouped with cycads, some studies suggest they may be more closely related to Bennettitales, or form a completely separate lineage altogether. Nilssonia typically refers to the leaf of the plant. In palaeobotany, it is common practice to give different names to plant parts like leaves, cones, and stems, since they are rarely found attached. In older literature, the whole-plant concept was sometimes called the “NilAnBe plant,” a combination of Nilssonia (leaves), Androstrobus (pollen cones), and Beania (seed cones). While the leaves and cones resemble those of cycads, the plant’s growth habit was very different. Modern cycads usually have an unbranched trunk with a single crown, or occasionally one that splits uniformly. In contrast, Nilssoniales had a central long-shoot with smaller short-shoots jutting off, each bearing its own crown of leaves and cones. This structure was more akin to a ginkgo branch. The stems were usually only a few centimetres thick, and many species likely grew as vine-like plants or small shrubs in the understory of Mesozoic forests.