Celaxryn RX What is the Tribulus Terrestris? Tribulus Terrestris is a flowering plant native to southern Europe, southern Asia, throughout Africa and in northern Australia. Tribulus terrestris has long been used as a male tonic and aphrodisiac in Indian Ayurveda. It is a natural testosterone booster used to build muscle and increase sexual desire and fantasies. Tribulus terrestris stimulates the secretion of sex steroids from the gonads, increases sperm motility and increases levels of joy and pleasure in sexual activity in both fertile and infertile men.