Cacti, often admired for their unique forms and resilience, are not typically thought of as “killer” plants. However, some species possess sophisticated defense mechanisms that can cause significant harm to humans and animals. These defenses, developed over millennia, range from physical deterrents to potent chemical compounds. Understanding these dangers allows for safe appreciation and interaction.
Understanding What Makes a Cactus “Killer”
Cacti have evolved defenses to protect themselves from herbivores in arid environments, crucial for preserving water and nutrients. These protective features are broadly categorized into physical and chemical forms.
Physical defenses include sharp spines and barbed glochids, which deter animals. Large size and dense growth patterns can also create impassable barriers. These structural elements offer protection and help in water conservation.
Beyond physical barriers, some cacti employ chemical defenses like irritating saps, toxic compounds, or hallucinogenic properties. These chemicals primarily protect against ingestion, making the plant unpalatable or harmful. Such dual defense strategies allow cacti to thrive in challenging conditions.
Cacti with Dangerous Physical Features
Cylindropuntia species, commonly called Cholla, are known for their specialized spines and growth habit. Cholla cacti have tiny, barbed glochids that easily detach upon contact. These glochids are difficult to remove and can cause skin irritation, itching, burning, and rashes. Some Cholla species, like the “jumping cholla,” have segments that readily break off and attach to passersby, increasing the risk of painful encounters.
The Saguaro (Carnegiea gigantea) is another large cactus, growing to immense sizes. Its body and branches are covered with straight spines that can inflict deep puncture wounds. While these larger spines are easier to remove than glochids, they still pose a risk of injury and potential infection.
Opuntia species, or prickly pear cacti, present a dual threat with larger spines and numerous glochids. Even spineless varieties can possess these tiny, irritating barbed hairs. Glochids embed deeply and resist easy extraction, leading to prolonged discomfort and contact dermatitis.
Cacti with Potentially Harmful Chemical Defenses
Some cacti contain chemical compounds harmful if ingested or if their sap contacts skin or eyes. The Peyote cactus (Lophophora williamsii), a small, spineless species, contains mescaline. Ingesting peyote can lead to hallucinations, altered perceptions, and physical effects like nausea, vomiting, increased heart rate, and elevated blood pressure. Due to its psychoactive properties, possession and use of peyote are illegal in many regions.
The San Pedro cactus (Echinopsis pachanoi), a tall, columnar species, also contains mescaline. Its effects are similar to peyote. San Pedro has a long history of traditional use in indigenous rituals for its hallucinogenic properties.
Certain Euphorbia species, though succulents and not true cacti, are often mistaken for them. They possess a milky latex sap that is highly irritating. It can cause severe skin irritation, including rashes, blistering, and pain upon contact. If the sap enters the eyes, it can lead to intense burning, swelling, and temporary blindness. Ingesting Euphorbia sap is toxic and can cause serious internal reactions.
Safety and First Aid When Encountering Cacti
Preventing cactus-related injuries involves careful awareness and precautions. When handling cacti, especially those with dangerous physical or chemical properties, wear thick, protective gloves, as cotton gloves offer insufficient protection against glochids. Use tongs or other tools to manipulate plants to prevent direct contact. Keep children and pets away from hazardous species to minimize accidental exposures.
If spines become embedded, immediate action can reduce discomfort and potential complications. For larger spines, sterilized tweezers can be used to pull them out. After removal, the affected area should be cleaned thoroughly with soap and warm water to prevent infection.
Removing glochids requires a different approach. Use fine-tipped tweezers to remove visible clumps. Then, apply a thin layer of glue over the affected area. Once dry, peel off the glue to pull out remaining glochids. Alternatively, pressing and quickly removing duct tape or other sticky tape can also help extract them.
For chemical exposure, flush the affected skin or eyes immediately with plenty of cool water for at least 15 minutes. If toxic cactus material is ingested or severe reactions develop, seek medical attention promptly. Monitor the affected area for signs of infection, such as increased redness, swelling, or warmth.