• (a.) Of or pertaining to an order of herbaceous plants (Primulaceae), of which the primrose is the type, and the pimpernel, the cyclamen, and the water violet are other examples.
Prim`u·la'ceous adjective (Botany) Of or pertaining to an order of herbaceous plants ( Primulaceæ ), of which the primrose is the type, and the pimpernel, the cyclamen, and the water violet are other examples. 
belonging to the plant family Primulaceae. Cf.