Few natural phenomena are as striking as the tree that appears to bleed when its bark is broken. This deep red or reddish-brown liquid is not blood, but a specialized plant exudate that flows in response to physical injury. This substance, often referred to as kino or dragon’s blood, is a concentrated mixture of compounds that a tree produces for its own defense and survival. The color and viscous texture have captured human curiosity for centuries, leading to both mythical interpretations and practical applications.
The Science Behind the Red Sap
The vibrant, crimson color of the exudate is due to a high concentration of secondary metabolites, which are organic compounds not directly involved in the plant’s normal growth and development. These include complex phenolic compounds such as tannins, anthocyanins, and flavonoids. When the tree sustains a cut or scrape, specialized cells release this resinous material to quickly seal the wound.
The sap serves as a biological defense mechanism against pathogens and pests. The tannins and other phenols are highly astringent and possess potent antimicrobial and antifungal properties that inhibit the growth of organisms attempting to enter the tree through the open wound. This colored sealant prevents the loss of water and nutrients while creating a physical barrier to deter insects and herbivores. Solidification of the sap ensures the tree can repair its structural integrity and continue to thrive after injury.
Notable Trees That Exude Colored Resins
One of the most famous sources of this deep red sap is the Dracaena cinnabari, commonly known as the Dragon’s Blood Tree, which is endemic to the island of Socotra, Yemen. This distinctive tree produces a resin that dries into garnet-red droplets collected by scraping the bark. The resin from this species, often considered the “true” dragon’s blood, has been traded internationally for thousands of years.
Another group of trees known for this trait are the Pterocarpus species, particularly the Indian Kino Tree (Pterocarpus marsupium) native to India and Sri Lanka. When incised, these trees exude a deep red resin known as “kino.” This kino is rich in polyphenolic compounds and is historically harvested for its medicinal properties and use in timber.
The Australian continent is home to the Bloodwood Gum trees, such as Corymbia opaca, which are part of the eucalyptus family. These trees produce a sticky, dark-red sap that local Aboriginal communities have long utilized. This particular kino is rich in tannins and gums, which help the tree survive the harsh, dry climates of the Australian desert.
Applications of the “Blood” in Medicine and Industry
The resinous exudates have been valued across human cultures since ancient times. Traditionally, the red resins were used as a powerful dye and pigment, including for varnishing musical instruments. The dried sap was also historically burned as a sweet-smelling incense in spiritual and ceremonial practices.
In traditional medicine, the resins are prized for their astringent and antiseptic qualities, making them a common remedy for wound healing. Indigenous communities applied the gum directly to cuts, sores, and burns to act as a topical antiseptic and stop bleeding. Internally, the resins were used to treat gastrointestinal ailments like diarrhea and mouth ulcers due to their antimicrobial and anti-inflammatory effects.
Modern scientific research continues to investigate the properties of these extracts, confirming the presence of numerous bioactive compounds, including flavonoids and lignans. These compounds exhibit antioxidant and anti-inflammatory activity, supporting the traditional uses for promoting skin repair and improving circulation. Beyond medicine, the high tannin content of certain bloodwood saps makes them useful as a natural tanning agent for preparing leather goods.