Oxalic acid is a white crystalline powder that is easily soluble in water. It got its name because it was first isolated from Japanese shikura, and it is an important metabolite of plants and microorganisms. For a long time, shikimic acid has been mainly extracted from the dry mature fruits of star anise or Japanese shikigum (Japanese fennel), etc. In recent years, there are also research reports on the extraction of shikimic acid from the fruits and pine needles of North American sweetgum.