Karl H. Bergius, pharmacist and naturalist, probably spent his youth in Berlin. There he was a school friend of the botanical collector J.L.L. Mund*, with whom he later served in the Prussian army. He was awarded the Iron Cross in the Napoleonic Prussian Campaign in 1813. He studied pharmacy in Berlin, but also had a strong interest in botany and zoology. Being an excellent student he came to the attention of Dr. M.H.K. Lichtenstein* of the Berlin Museum, who recommended him for employment as assistant in the firm of Pallas and Polemann*, apothecaries in Cape Town. Lichtenstein expected him to collect specimens for the Berlin Museum in his spare time.
Bergius arrived in Cape Town in May 1815. Though his free time was limited to one day per month and his means were small, he collected plants, birds, insects, mammals, reptiles and other zoological speciments for Lichtenstein with enthusiasm, often in the company of local or visiting naturalists. A good friend to him was the botanical collector Rev. C.H.F. Hesse*. He met and collected with W.J. Burchell*, botanist C.G.C. Reinwardt*, entomologist B.W. Westermann*, G.L.E. Krebs*, and two collectors for the Berlin Museum, his friend Mund and L. Maire*.
Bergius's conditions of employment, and particularly his treatment by Polemann, caused him great unhappiness, leading to his resignation from the firm in July 1817. However, he had very little money and received no financial or other support from his family in Germany or from Lichtenstein. Despite suffering from the increasing effects of pulmonary tuberculosis he tried to make ends meet by collecting and selling natural history specimens to European museums. He preferred collecting plants, as the preservation of his zoological specimens proved difficult and often beyond his means. His favourite plants were the Cape orchids, which he collected, described and painted with Mund and on which they planned to produce an illustrated publication. This was, however, never finished. By December 1817 Bergius had a collection of insects ready to be shipped to Berlin, containing mainly small and lesser known species. He was planning to move to Plettenberg Bay for the sake of his health, and from there to undertake a journey with Mund to the territory of the Bechuanas. However, nothing came of this and he died of his illness, poor and neglected, in January 1818. His remaining collections, writings and drawings were sent to Berlin. Many of his plants ended up in the Regio Museo Botanica, Berlin. Other specimens are in the Natural History Museum of the Humboldt University in Berlin.
Bergius was commemorated in the names of the plant species Diascia bergiana, Melanthium bergii, Ophioglossum bergianum, and Ficinia bergiana. The Swift Tern, Sterna bergii, of which he collected the first specimen near Cape Town, was named after him by Lichtenstein in 1823.