Mary Johnston(e) Lynn (9 January 1891 – died after 1959) was an Irish botanist known for her phyto-ecological studies in Northern Ireland.
She attended Queens University, Belfast for undergraduate and postgraduate studies, earning a bachelor's degree in 1914 and a doctorate in 1937.
[4] She was an active member of the Belfast Naturalists Field Club[5] and the Botanical Society of Northern Ireland,[6] and studied plant cell biology,[7] including the effect of carbon dioxide and rotation on the curvature of sunflower stems.
[15] She was publishing her research as late as 1960, when she updated a coastal survey of Larne Lough,[16] and reported on the appearance of Datura stramonium in Ireland.
Algae specimens collected by Lynn were part of the Algal Herbarium at Queens University, Belfast.