Dicotyledonous plants (dicotyledonous plants for short), formerly known as Dicotyledonous Plants and Magnolia, refer to flowering plants with two leaflets, with about 199350 species. 1 A flowering plant that is not a dicotyledonous plant is called a monocotyledonous plant and generally has only one cotyledon. Unlike monocotyledons, dicotyledons can thicken the stems. But later research gradually made botanists realize that monocotyledonous plants actually evolved from ancient dicotyledonous plants and were one of the specialized branches of dicotyledonous plants, which made the traditional dicotyledonous plants classified as a joint group and no longer regarded as an effective classification. Dicotyledonous plants are no longer considered as a suitable group name, at least in the sense of classification. But most of the dicotyledonous plants mentioned above can be divided into a branch of true dicotyledonous plants in a single line. This single system can be distinguished from other flowering plants by pollen structure. The pollen of other dicotyledonous plants and monocotyledonous plants is single furrow or single furrow derivative model; However, the pollen of real dicotyledonous plants is in the form of tri-furrow or tri-furrow derivatives, and there will be three or more holes in the furrows of the pollen.