The natural world presents many intriguing phenomena, including certain trees exuding a striking red-colored sap. This occurrence, sometimes likened to a tree bleeding, stems from unique biological processes. The vibrant crimson liquid has captured human attention for centuries, sparking both curiosity and practical applications. This characteristic appears only in specific trees that have evolved distinct mechanisms for producing such a vivid exudate.
Trees with Distinctive Red Sap
Several tree species worldwide are renowned for their red sap. One of the most famous is the Dragon’s Blood Tree (Dracaena cinnabari), native to Yemen’s Socotra Archipelago. This tree produces a deep red resin when its bark is damaged, and its unique umbrella-shaped canopy is a striking feature. Another notable example is the African Bloodwood tree (Pterocarpus angolensis), found across southern Africa. When cut, this tree releases a dark red, sticky sap that resembles blood, known locally as Kiaat, Mukwa, or Muninga.
Australian Bloodwood trees, primarily Corymbia and Eucalyptus species, also yield a dark red sap known as kino. The Red Bloodwood tree (Corymbia gummifera), for instance, exudes a deep red kino when its bark is damaged, used by Indigenous Australians. Other Eucalyptus species, like Eucalyptus camaldulensis, also produce this reddish-brown gummy exudate. The Desert Bloodwood (Corymbia opaca) is another Australian tree known for its dark red sap, which oozes readily when injured. These trees typically grow to significant heights and often have rough, fibrous bark.
A different type of “dragon’s blood” resin comes from Croton lechleri, a tree native to the Amazon. This fast-growing tree produces a thick, red sap when its bark is damaged. Various Pterocarpus species, including the Indian Kinotree (Pterocarpus marsupium), are also known for their red sap.
The Science Behind Red Sap
The red coloration in these tree saps is due to specific chemical compounds. Many red saps, particularly those referred to as “kino,” contain high levels of tannins and other polyphenols. For example, Pterocarpus angolensis sap contains a significant concentration of tannins, sometimes as high as 77%. These compounds are responsible for the sap’s bitter or astringent taste and its characteristic color.
When a tree is wounded, it produces an exudate as a defense mechanism, analogous to how an animal might bleed. This exudate, which can be sap or resin, seals the wound, preventing moisture loss and protecting against pests and pathogens. The red sap acts as a natural bandage, helping the tree to heal by forming a protective layer.
The chemical composition of these red saps often includes compounds like proanthocyanidins (condensed tannins), alkaloids, and flavonoids. Taspine, for example, is a component found in Dragon’s Blood sap that has anti-inflammatory and wound-healing properties. These chemical constituents contribute to the sap’s protective functions, deterring herbivores and inhibiting microbial growth.
Cultural and Practical Uses
Red sap from these trees has been utilized for a variety of cultural and practical purposes for millennia. Dragon’s Blood resin, from species like Dracaena cinnabari and Croton lechleri, has been highly valued since ancient times. Romans and other early civilizations used it as a medicine and as a red dye. It has also been used as a varnish, particularly by 18th-century Italian violinmakers, and as a pigment in paints.
In traditional medicine, the red sap is frequently applied topically to treat wounds, burns, and skin abrasions due to its astringent and antiseptic properties. Indigenous Australians, for instance, used the sap from Desert Bloodwood for sore eyes, wounds, burns, and as a tanning agent. The sap of Pterocarpus angolensis has been used to treat ringworm, eye problems, and to stimulate breast milk production. Some red saps have also been used internally for gastrointestinal issues such as diarrhea and dysentery.
Beyond medicine, red sap has found applications as a cosmetic and a dye. The sap from Pterocarpus angolensis has been mixed with animal fat to create cosmetics for faces and bodies, and its sticky red sap leaves a permanent stain on cloth, making it an effective dye. The Indian Kinotree’s gum, also known as “kino,” has been used in traditional Indian medicine and as a dye.