Source : Webster's Revised Unabridged Dictionary (1913)

Houstonia \Hous*to"ni*a\, n. [NL. So named after Dr. William
   Houston, an English surgeon and botanist.] (Bot.)
   A genus of small rubiaceous herbs, having tetramerous
   salveform blue or white flower. There are about twenty
   species, natives of North America. Also, a plant of this
   genus.