ar·bo·re·tum 
(är′bə-rētəm)
(är′bə-rētəm)n. pl. ar·bo·re·tums or ar·bo·re·ta (-tə)
A place where an extensive variety of woody plants are cultivated for scientific, educational, and ornamental purposes.
[Latin arborētum, a place grown with trees, from arbor, tree.]