Mary Eva Hastings Morris was born on 9 April 1873 in Dolgelly, Montgomeryshire, the daughter of the Rev Samuel Morris, a naval chaplain. She attended the High School for Girls in Camarthan. Between 1890 and 1893, she lived in Malta, presumably as her father was serving on HMS Victoria, the navy’s flaship in the Mediterranean. In 1893, HMS Victoria was rammed by HMS Camperdown and sank, with the loss of 321 sailors, including Mary’s father. When Admiral Tyron gave the order Abandon Ship! Every Man for Himself the Reverend Morris was reported to have stayed on board, trying to rescue the sick: "In the hour of danger and of death, when all were acting bravely, he was conspicuous for his self-denying and successful efforts to save the sick and to maintain discipline. Nobly forgetful of his own safety, he worked with others to the end, and went down with the vessel ... seeing escape impossible he folded his arms upon his breast, and looking up to heaven, his lips moving in prayer, he died."
Mary returned to live with relatives, probably her mother Mrs SO Morris, in Wales and studied at the University College of Wales at Aberystwyth. In 1895, she studied at the London School of Medicine for women, becoming an M.D. Mary was a surgeon at the North Devon Infirmary and later worked with outpatients at the Bristol Royal Hospital for Sick Children and Women. She moved to Bath in 1908, becoming the first woman doctor to practise in the city.
Mary Morris was present at a 1908 meeting in Bath with Lilias Ashworth Hallet and the visiting Millicent Fawcett, leader of the moderate suffragette organisation, the NUWSS. Mary was also present when Millicent planted her own tree in Annie’s Arboretum in 1910. It is possible that Mary knew Elizabeth Garett Anderson, the founder of the London School of Medicine for Woman and Millicent Fawcett’s sister. A Mary Morris is listed in the Roll Honour of imprisoned women, but given Dr Morris’ association with Millicent Fawcett and Lilias Ashworth Hallet, it seems likely she was a moderate.
Mary planted an illex aquifolium laurifolia on 20 February 1911.
During WWI, Mary worked as a pathologist in the Bath War Hospital. At the time of her death on 11 July 1925, she was living in Gay Street, Bath and a large number of people attended a memorial service in the Abbey. She was buried in Cardiganshire.