"Luo bu ma" (Apocynum venetum) belongs to Apocynaceae (the Dogbane family). It is a perennial herb that is distributed to China, India, Pakistan, southwesten Asia, southern Europe and North Africa. It herb grows in barrens, desert margins, swamps and maritime sands and can reach 1-4 m in height. Leaves are narrowly elliptic to narrowly ovate and usually opposite. The purplish red or pink tubular flowers appear from April to September. The inner barks contain strong fibers and are used in making cloth and string. The leaves are used as a herbal medicine for sedative and to treat hypertension.