Ellen Wright Blackwell was born at Northampton, Northamptonshire, England, on 7 October 1864, the daughter of Annie Maria Bumpus and her husband, John Blackwell, a master hosier. Ellen was one of a large family and was brought up as a Baptist. Over the years she developed a deep amateur interest in botany. She also wrote religious books for children under the pen-name of Grace Winter; the first, Keep to the right, was published in 1900.
Two of Ellen's brothers, Frank and William Blackwell, had settled in New Zealand in the early 1880s and farmed on the Pahi River on the Kaipara Harbour, although William subsequently shifted to Auckland. In 1903 Ellen, 39 years old and unmarried, sailed for New Zealand on the Omrah to visit her brothers. Another passenger, Robert Laing, returning to New Zealand, boarded the ship at Naples. Laing was a secondary school teacher in Christchurch with a strong interest in botany, and had by this stage published 10 scientific papers, mostly on marine algae. He was almost the same age as Ellen and also unmarried. The two travellers discovered their common interest in plants and went ashore together at some of the ports of call. A friendship was established and they remained in touch in New Zealand.
After arriving in Auckland, Ellen visited her brother Frank at Pahi in January 1904. Ellen marvelled at the vegetation of the local bush, a feeling shared by Frank, who had also developed considerable skill as a photographer. She remained in New Zealand for three more summers, visiting other areas, then with Robert Laing set out to produce a book, Plants of New Zealand. It was first published in 1906 under the joint authorship of R. M. Laing and E. W. Blackwell, with 160 original photographs by E. W. and F. B. Blackwell.
No semi-popular, comprehensive, well-illustrated book on the plants of New Zealand had been available previously. Laing and Blackwell's was to become a botanical classic running to seven editions over the next 60 years. Several generations of people interested in New Zealand's native plants were to use it as a constant reference book and a number of professional botanists would credit it with stimulating their original interest. The reasons for the book's success can be readily seen. All the common species were covered, it was well illustrated with skilful use of photographs, and it referred to Maori uses. In the general sections it also replaced some of the usual dry botanical descriptions with more readable, even semi-poetical language.
Unfortunately, Ellen Blackwell received little credit for her part in the work. Contemporary reviewers such as Leonard Cockayne largely ignored her contribution. Local botanists, all male, appear to have held strong views on the place of women. Yet Blackwell obviously made a major contribution to the first edition. Although many of the photographs taken around the Kaipara Harbour were Frank's, some were Ellen's. Much of the information on species such as kauri, nikau, mangrove and pohutukawa could only have been written by someone who knew them well, and these trees did not occur in Canterbury where Laing lived and had mainly worked. Laing, however, was well known among New Zealand scientists, both through his published work on algae and from his distinguished service to the Philosophical Institute of Canterbury. In July 1906 a clergyman, T. F. Robertson, defended Blackwell in the New Zealand Herald and argued that she deserved proper credit. Ellen herself took no part in any of the controversy, and indeed tried to divorce herself from it. Laing appears to have made no effort to put matters straight.
Ellen Blackwell went back to England shortly after the book was published and never returned to New Zealand. Her part in subsequent editions was probably minimal. Little was known of her life in New Zealand until a book about the early settlers on the Pahi River by Dick Scott was published in 1987.
In London on 14 October 1910 Ellen Blackwell married Thomas Maidment, a widower who was the branch manager of an insurance company. Ellen's publishing seems to have been confined to two further religious books for children, appearing in 1923 and 1926. She died in Portsmouth on 24 February 1952. Her husband had predeceased her. There appear to have been no children of the marriage.