[1][3] Scannell became Assistant Keeper of the Natural History Division of the National Museum, Ireland, 1949.
She was an expert in the identification of woods and charcoals, leading her to identify the material used in all the Irish harps in the National Museum[4] as well as from archaeological sites.
[1] The Botanical Society of Britain and Ireland called her "an inspiration to generations of botanists" for her taxonomic knowledge of seeds and fibres as well as microfungi and algae.
Her very wide knowledge within botany, particularly of Ireland and the Herbarium collection, is illustrated in the diversity of publications that acknowledge her contribution or advice: a follow-up to a record of Salix hibernica in Ireland in 1963 records her contribution of information from the Herbarium indicating the tree's presence in Ireland substantially earlier, in the 1880s;[5] Identifying the species of reeds in a print of an oil painting in 1996 led to its identification as an important post-Famine Irish landscape painting;[6] Identification of wood and charcoal fragments for archaeological excavations.
[7] Over 200 scientific publications, books and floras are attributed to her, in addition to specimExpandens and field records deposited in the national Herbarium.