Metz's wild petunia (Ruellia metzae) belongs to Acanthaceae (the Ruellia family). It is a perennial herb that is native to south-central United States, Texas. This herb grows in mesquite areas, oak mottes, stream beds and limestone hills, and can reach about 60 cm in height. The leaves are ovate with coarse toothed edges. The white flowers bloom from May to October.