Lefroy was known primarily for the discovery of the
purple spurge. Purple spurge is a species of
Euphorbia; it usually grows on gravelly and sandy beaches. It has traces to western Europe and northern Africa. The plant is a small, prostrate plant with four stems at the base growing between long. She found this in
Tramore, Waterford in 1839. Other botanists attempted to visit the area where she discovered it but they failed, which led people to believe it was very rare and now extinct. Rob Randall mentions this plant in his annual report in 1978 where he visits
Lundy. He is puzzled by the fact that this plant is found on certain beaches on the island and not others. ==Other Discoveries==