Carl Ludwig Willdenow (22 August 1765 – 10 July 1812) was a German botanist, pharmacist, and plant taxonomist. He is considered one of the founders of phytogeography, the study of the geographic distribution of plants. Willdenow was also a mentor of Alexander von Humboldt, one of the earliest and best known phytogeographers. He also influenced Christian Konrad Sprengel, who pioneered the study of plant pollination and floral biology.