Mary Anderson Grierson (September 27, 1912-January 30, 2012) was a Welsh-born Scottish illustrator and longtime staff artist at the Royal Botanic Gardens, Kew.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Mary_Grierson
Epigeneium Coelogyne by Mary Grierson
ND / Watercolor on paper / 15-3/4″x11-2/5″ / Shirley Sherwood Gallery at Kew, London, UK
Mary Grierson on Artnet: http://www.artnet.com/artists/mary-grierson/