Depends where she's at career wise.
The Brian Capon is an excellent introductory text for both amateur and
professional gardeners and he relishes his subject as the reader usually
will.
Travel/adventure/gardening - Valley of Flowers by F. S. Smythe - it's out
of print but widely available.

Rod

Thanks for the feedback on Brian Capon and the F. S. Smythe suggestion, I'll
look into it.

Tim