Anyone poisoned by the Sui tree may not survive more than 7 steps uphill, 8 steps downhill, or 9 steps on flat ground.
The Sui tree, also known as the Poison Arrow tree, has the scientific name Antiaris toxicaria. This large tree can grow up to 30 meters tall and is distributed in tropical regions of Asia, Africa, and Australia. In Vietnam, the Sui tree is commonly found in the northern mountainous areas such as Hà Giang, Lạng Sơn, Thái Nguyên, and several provinces like Quảng Trị, Đồng Nai, Bà Rịa – Vũng Tàu, etc.
The Antiaris toxicaria has many different local names. On the island of Java in Indonesia, this poisonous tree is called Xuy, while on Hainan Island in China, it is referred to as the “Poison Arrow Tree” because ancient Chinese used the tree’s toxin to coat the tips of arrows for hunting and warfare.
The mature Sui tree can have a diameter of up to 40 cm, with elliptic leaves measuring 7–19 cm in length and 3–6 cm in width, and light gray bark. The tree grows quickly and reaches maturity in about 20 years.
The Sui tree contains the famous cardenolides glycoside toxin, which is used to coat arrows and darts. Therefore, in Java, the Sui tree is also referred to as Xuy, which means “poison,” and has nicknames like “guard” or “messenger.”
In China, this species is considered extremely dangerous. Folklore suggests that anyone poisoned by the Poison Arrow Tree will die after 7 steps uphill, 8 steps downhill, or 9 steps on flat ground. The toxin of the Sui tree can attack the heart of the victim, quickly causing cardiac arrest, leading to limpness, pale complexion, suffocation, and death.
Scientists advise against close contact with the Sui tree. The sap of the Sui tree can cause blindness if it enters the eye, and contact with wounds can lead to absorption into the bloodstream, resulting in death if not treated promptly.
Despite its deadly toxin, the Sui tree is currently being used in medicine to formulate certain types of medications for fevers, heart support, high blood pressure, etc.
