Her Majesty's Botanist

His/Her Majesty's Botanist is a member of the Royal household in Scotland.

The office was created in 1699, and from 1768 until 1956 it was combined with the office of Regius Keeper of the Royal Botanic Garden Edinburgh, who also held the post of Regius Professor of Botany at the University of Edinburgh. Since then the office of HM Botanist has been honorary, but conferred on a serving or retired Regius Keeper.

...
Wikipedia