The Collaborative International Dictionary of English v.0.48:

Rubiaceous \Ru`bi*a"ceous\, a. [L. rubia madder, fr. rubeus
   red.] (Bot.)
   Of or pertaining to a very large natural order of plants
   (Rubiaceae) named after the madder (Rubia tinctoria), and
   including about three hundred and seventy genera and over
   four thousand species. Among them are the coffee tree, the
   trees yielding peruvian bark and quinine, the madder, the
   quaker ladies, and the trees bearing the edible fruits called
   genipap and Sierre Leone peach, besides many plants noted for
   the beauty or the fragrance of their blossoms.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Rubiaceae
    n 1: widely distributed family of mostly tropical trees and
         shrubs and herbs; includes coffee and chinchona and
         gardenia and madder and bedstraws and partridgeberry [syn:
         Rubiaceae, family Rubiaceae, madder family]