Uruguayan chemist and botanist. Arrillaga was born in the north of Uruguay in the department Artigas from where she moved to Montevideo and studied to become a pharmaceutical chemist in the Faculty of Chemistry (University of the Republic). In 1951 she became a botany teacher here, before continuing the same role in the Faculty of Agronomics. Arrillaga specialised in the histological study of Uruguayan plants and their taxonomy and has published many works in the field, both in her own country and abroad (Argentina and Canada). She has undertaken many fieldwork trips, collecting plants for her studies and to add to the collections at in the Faculty of Agronomy and has taken part in numerous projects with this faculty and that of Chemistry. A visiting researcher at the Smithsonian Institution, Washington, and the New York Botanical Gardens she has presented works at various botanical congresses. Her most important publications include 'Nuevas especies y notas taxonómicas en Uruguay y Paraguay' (1968) in collaboration; Plantas Medicinales (1969) and Gramíneas Uruguayas (1970) with B. Rosengurtt and P. Izaguirre de Artucio.