The pin-leaf vervain (Verbena perennis) belongs to Verbenaceae (thr Verbena family). It is a perennial herb that is native from Arizona to Texas in the southwestern United States, and northern Mexico. This herb grows in grassy, rocky ridges, canyons and hillsides, and up to a height of 60 cm. The stems branch regularly, from the widely-spaced leaf nodes. They usually have a fine covering of very short, stiff hairs, often slightly glandular. The leaves are short and linear, with a lighter-colored midvein. The leaf margins are rolled under. The pink to bluish flowers bloom in the narrow, elongated inflorescence from March to May. They mature from the base of the cluster upwards.