Robert Knuds Friedrich Pilger was a German botanist who collected plants in Brazil. His publications numbered around 200, including Das system der bluetenpflanzen (1908), and his contributions as one of the editors (with A. Engler and others) of Die natuerlichen Pflanzenfamilien. Several of his publications dealt with a single plant family, including the Taxaceae (1903), Santalaceae (1925), Cycadaceae (1926), Coniferae (1926), Cupressaceae (1926), Santalaceae (1935), Plantaginaceae (1937) and Gramineae (grasses, in several parts). He seems to have been associated with the Botanical Garden and Botanical Museum at Berlin-Dahlem for most of his career. In 1943, during World War II (1939-1945), he reported on the institution and from 1945 to 1950 served as its director. The genera Pilgerodendron and Pilgerochloa were named after him.
Several of Pilger's publications dealt with plants from German South West Africa (now Namibia), though it is not clear whether he visited the territory: 'Algen aus Suedwestafrika' (Algae from South West Africa, Hedwigia, 1908); 'Suedwestafrikanische Futtergraeser' (South West African fodder grasses, Notizblatt der Botanische Garten zu Berlin, 1910); 'Die Gattung Wellstedia in Suedwest-Afrika' (The genus Wellstedia in South West Africa, Botanische Jahrbuch, 1912), and 'Die grasvegetation der Farm Okainapuro in Deutsch-Suedwest-Afrika' (The grass vegetation of the farm Okainapuro in German South West Africa, Notizblatt der Botanische Garten zu Berlin, 1913).