| Houstonia | ‖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. [ Webster 1913 Suppl. ] |
| houstonian | |
| houstonian |
| common ageratum | (n) small tender herb grown for its fluffy brushlike blue to lavender blooms, Syn. Ageratum houstonianum |