The term “bleeding tree” refers to diverse plant species that exude a deeply colored, often vibrant red or dark crimson substance when their bark or wood is damaged. This phenomenon visually resembles the flow of blood, but the expelled material is not true blood. It is a concentrated form of sap or resin, which is the tree’s natural response to injury. This unusual, pigmented fluid has been a source of fascination across various cultures for centuries.
The Biological Mechanism of Exudates
The expulsion of this crimson fluid, categorized as an exudate, is a biological defense mechanism that protects the tree. When the trunk or branches suffer a mechanical wound, insect attack, or pathogen invasion, the tree quickly mobilizes this substance to the site of injury. Its primary function is to physically seal the breach, acting like a natural bandage that prevents moisture loss and blocks the entry of harmful microorganisms and pests.
The specific type of exudate determines its chemical composition and physical properties. In many angiosperms, the red substance is known as kino, a phenolic compound rich in tannins, which polymerize and harden rapidly upon exposure to air. This rapid hardening effectively seals the wound. Other species produce a red-pigmented resin, comprised mainly of terpenes, or a colored latex; both serve the same protective purpose.
The red or dark coloration is due to high concentrations of organic compounds produced by the plant. In species that produce kino, the color is primarily derived from astringent tannin compounds and their oxidized derivatives, often called kino red. These phenolic compounds are potent antioxidants and possess antimicrobial properties, providing a chemical layer of defense against fungi and bacteria that attempt to colonize the wound.
Prominent Global Species
The most famous example of this phenomenon is the Socotra dragon tree, Dracaena cinnabari, native to the Socotra archipelago in Yemen. This species has a dense, upright crown that gives it an inverted umbrella or mushroom-like appearance. When its bark is cut, the tree secretes a deep red resin, known historically as Dragon’s Blood, which solidifies into brittle, dark pieces.
Another example of “bleeding trees” is the African bloodwood, particularly species within the genus Pterocarpus, such as Pterocarpus angolensis. Found across Southern Africa, this tree is valued for its timber. Its common name comes from the deep red kino that flows freely from any incision, which defends the tree against drought conditions and intense insect pressure common in its native habitat.
In Australia, species of Corymbia and Eucalyptus, collectively known as bloodwoods, also produce a dark red exudate. For instance, the Marri tree, Corymbia calophylla, exudes dark crimson kino, which stains the trunk and surrounding soil. This gum-like substance is chemically distinct from the dragon’s blood resin but performs the same protective function against environmental threats.
Traditional and Modern Applications
The “bleeding” fluid was widely adopted in traditional medicine and artisanal practices. Historically, the resin from Dracaena species was used as a dye for various materials. Notably, it is believed to have been a component in the varnish used on 18th-century Stradivarius violins, imparting a rich, deep hue. The kino from Pterocarpus species was often used as a folk remedy for various ailments.
In traditional medicine, the exudates were valued for their healing properties, particularly for treating wounds, ulcers, and diarrhea. This historical use is supported by modern scientific investigation isolating the bioactive compounds within the substances. Research focuses on the high concentration of phenolic compounds, such as flavonoids and proanthocyanidins, which exhibit antioxidant, anti-inflammatory, and antimicrobial activity.
The extracts from these exudates are now being studied for applications in pharmaceuticals and nutraceuticals. The resin from the Croton lechleri tree, often called Sangre de Grado, has been clinically investigated for its wound-healing and anti-diarrheal effects. The ancient uses of these materials have transitioned into a modern search for scientific validation of their therapeutic and industrial potential.