In ancient Sumeria, hundreds of medicinal plants including myrrh and opium are listed on clay tablets. The ancient Egyptian Ebers Papyrus lists over 800 plant medicines such as aloe, cannabis, castor bean, garlic, juniper, and mandrake.[14] From ancient times to the present, Ayurvedic medicine as documented in the Atharva Veda, the Rig Veda and the Sushruta Samhita has used hundreds of pharmacologically active herbs and spices such as turmeric, which contains curcumin.[15][16] The Chinese pharmacopoeia, the Shennong Ben Cao Jing records plant medicines such as chaulmoogra for leprosy, ephedra, and hemp.[17] This was expanded in the Tang Dynasty Yaoxing Lun.[18] In the fourth century BC, Aristotle's pupil Theophrastus wrote the first systematic botany text, Historia plantarum.[19] In around 60 AD, the Greek physician Pedanius Dioscorides, working for the Roman army, documented over 1000 recipes for medicines using over 600 medicinal plants in De materia medica. The book remained the authoritative reference on herbalism for over 1500 years, into the seventeenth century.[4]