Succulents are plants with thick, fleshy parts adapted for storing water in arid climates. While many varieties have smooth leaves, a significant number of popular species are covered in sharp structures, ranging from fine bristles to rigid points. These sharp features are an evolutionary solution to the harsh conditions of their native environments, promoting survival.
The Biological Purpose of Spines and Thorns
Sharp structures are an evolutionary adaptation promoting survival in challenging environments. Their primary function is mechanical defense against herbivores seeking the plant’s stored water and nutrients. Larger, rigid spines deter large mammals, while finer bristles discourage smaller insects and pests.
These sharp growths also help manage the plant’s environment. A dense covering of spines creates shade, reducing the plant’s surface temperature and preventing sun scorch. This shading minimizes the rate of transpiration, conserving internal water reserves. In certain species, structures like the tiny, barbed hairs known as glochids can collect condensation, channeling dew or fog droplets down to the soil for absorption.
Identifying Common Spiky Varieties
The terminology for a succulent’s sharp points is not interchangeable because the structures originate from different parts of the plant.
Spines
True spines are modified leaves featured on cacti, developing from specialized structures called areoles. These spines are often woody, long, and stiff, such as those found on the Golden Barrel Cactus (Echinocactus grusonii).
Glochids
Glochids are minuscule, fine, and barbed bristles found on Opuntia species, like the Bunny Ears Cactus. They detach easily upon contact and are irritating to the skin.
Thorns and Teeth
Thorns are modified stems or branches, a feature seen in many Euphorbia species, such as the Crown of Thorns (Euphorbia milii). Plants like Agave and some Aloe species possess sharp, fibrous teeth along the margins of their leaves. These teeth are extensions of the leaf tissue.
Specific Care for Spiky Succulents
Spiky succulents, especially cacti, often originate in environments with intense sunlight. They generally require more direct light than soft-leaf varieties. Placing them near a south- or east-facing window is ideal to ensure they receive several hours of bright light. This prevents stretching and paleness, a condition known as etiolation. If grown outdoors, gradually introducing them to full sun is important to avoid tissue burn.
The soil mixture is important for these species, which thrive in a porous substrate mimicking their natural rocky habitats. A commercially available cactus and succulent mix, often amended with materials like perlite or pumice, provides the superior drainage necessary to prevent root rot. Watering should follow the “soak-and-dry” method. Water thoroughly until it runs out of the drainage holes, then allow the soil to dry out completely before the next application. During the colder, dormant months of winter, reduce watering frequency significantly to align with the plant’s rest cycle.
Safe Interaction and Placement
Proper handling and placement are important due to the physical hazards of spines and the chemical risks of certain species. When repotting or moving a spiky plant, use tools to provide a secure grip without injury.
Tools for handling include:
Kitchen tongs
A folded newspaper strip
A thick piece of foam
For plants with fine glochids, which easily penetrate standard gardening gloves, a thick barrier or specialized technique is recommended.
The latex sap in many Euphorbia species contains compounds that can cause skin irritation, blistering, and severe eye inflammation. When pruning these plants, wear thick gloves and eye protection. Any exposed skin that contacts the milky sap should be washed immediately with soap and water. For safety, place plants on high shelves or in hanging planters, keeping them out of reach of pets and small children.