Papers, 1887-1977, relating to Blackwell's time as Head of Botany at Royal Holloway College, University of London, notably correspondence with her parents, 1922-1945, discussing life at Royal Holloway College; letters of congratulation on her appointment as Head of Botany at Royal Holloway College, 1922; correspondence and notes, 1928-1949, relating to gifts to Royal Holloway College; personal correspondence, 1941-1970, notably with Ellen Charlotte Higgins, former Principal of Royal Holloway College, (Elsie) Marjorie Williamson, Principal of Royal Holloway College, and John Cameron; papers, 1887-1969, relating to the Royal Holloway College Botany Department, including Botany Lunches, 1949-1977, Botany School Record Books, 1887-1969, and correspondence relating to field trips, 1930-1944; Blackwell's copies of the Royal Holloway College Boat Club Rules, 1914-1918, and the Royal Holloway Rules and Regulations, 1925; notes, memoranda, correspondence, minutes and reports of the University of London Botanical Supply Unit, 1944-1952; invitations and Christmas cards, 1922-1963; autograph books, 1922-1950, including one presented to Blackwell by her old students and staff at a luncheon at the Forum Club, [London], 1950. Records, 1897-1971, relating to the history of Royal Holloway College and the Botany Department, including press cuttings, photographs, memoirs, correspondence and draft articles, notably and article by Blackwell entitled '75 years of Royal Holloway College Botany Department', copies of College songs, and obituaries of old colleagues and students. Publications, 1902-1949, mainly comprising histories of the Botanical Departments of Liverpool and Manchester Universities. Photographs, 1880-1970, including the Botany Department staff and students, 1898-1962; Botany Department field trips, 1898-1948; Royal Holloway College staff, buildings and grounds, 1908-1952; Botany laboratories and gardens, 1912-1949; social and botanical activities at Royal Holloway College, 1927-1955.