Euan Hillhouse Methven Cox (1893–1977) was a Scottish plant collector, botanist, and horticulturist, who accompanied Reginald Farrer on his last botanical expedition to Burma and its border with China, from 1919 to 1920.

He was a very successful propagator of rhododendrons and had an extensive collection in his garden at Glendoick, Perthshire, Scotland, which formed in 1953 the basis of his commercial nursery, later run by his son, Peter A Cox, and grandson, Kenneth N.E.

[1] The enterprise introduced many dwarf hybrids,[2] suitable for the Scottish climate.

[4] The commercial nursery, with Britain’s largest selection of rhododendrons, developed a major tourist attraction consisting of an expansive garden centre, an award-winning café, and a series of woodland spaces filled with plants collected by or grown by the Cox family.

[3] In 2001 Kenneth Cox discovered the species R. titapuriense in Arunachal Pradesh, northeast India near the border with China.