Portuguese botanist, professor and director of the botanic garden at the University of Coimbra, Luis Wettnich Carrisso succeeded Júlio Henriques in a variety of roles and carried on his vital promotion of the plant sciences in Portugal. Also interested in the flora of Portugal and Angola he collected in both countries.

Born in the parish of Julião in Figuera da Foz to a Portuguese father and German mother he grew up speaking both languages. After completing his schooling at the Liceu Figueirense Carrisso went on to study at the University of Coimbra, receiving a bachelor's degree in 1910 and a PhD in natural philosophy in 1911 with a thesis on the plankton of the Portuguese coast. Carrisso had also worked for a time in Geneva, under Professor R. Chodat, where he became greatly interested in ecology and phytogeography.

In 1912 he gained a position as assistant to the Biological Sciences Group at the museum and in 1918 was promoted to professor; he also acted as secretary of the Faculty of Sciences at the university between 1917 and 1919. At the same time Júlio Henriques retired from his post as director of the Botanic Garden of Coimbra and Carrisso took over, taking on the botanic museum and the laboratories at the same time. Directing the institute (which became the Botanical Institute 'Dr. Júlio Henriques') until his death in 1937, Carrisso developed the garden which had suffered badly at the hands of the Great War, and, despite a constant lack of funds, he greatly enhanced the variety of plants cultivated there and changed the organisation for a greater educational impact.

At this time the Bulletin of the Broterian Society (the publication of the botanical society of Portugal) was suffering due to the advancing years of its founder and editor (Henriques) and Carrisso revived the periodical by beginning its second series as well as creating another means of disseminating the society's news, the Memórias da Sociedade Broteriana which he founded in 1930. During his lifetime he published 29 scientific and historical works, including several on myrmecophily (the interspecific relationship between ants and other organisms, particularly plants).

While teaching plant taxonomy, anatomy, physiology ecology and pharmacology Carrisso conducted research into the local Portuguese flora. He also developed a particular interest in the flora of the former Portuguese colony of Angola which he first visited in 1927 with F. A. Mendonça, bringing back valuable collection from Lunda, a province barely studied previously. Later he ran a successful project taking a group of students from universities in Portugal to the same territory in Angola. In total he would travel to Angola three times, always accompanied by his wife Ana Maria Costa Pereira de Sousa, and using plants collected by himself and colleagues on these trips Carrisso began to write his Conspectus of the Flora Angolensis. This was a project in collaboration with the Botany Department of the British Museum, but he had only edited and published the first volume when he died suddenly of a heart attack in the Namib Desert on his third trip to Angola.

Much of Portugal mourned the death of Carrisso, who was a popular public figure occupying many state administrative roles, including president of the Coimbra municipality, representative of the National Assembly, member of the Imperial Council and president for the Commission for the Construction of Schools. The genus Carrissoa Bak. and the species Ritchiea carrissoi Exell and Mendonça bear his name.

Sources:
J. Guimarães, "Carrisso, Luís Wittnich, 1886-1937", Biblioteca Digital de Botânica:
http://bibdigital.bot.uc.pt/index.php?menu=5&language=eng&tabela=geral, accessed February 2010.
A.W. Exell, 1937, "Obituary: Dr. L. W. Carrisso (1886-1937)", Rendle. Journal of Botany, 75: 356-357.