The “glue plant” refers to Drosera species, or sundews. They are known for producing a glistening, sticky mucilage on their leaves, which attracts and captures small insects. This carnivorous adaptation allows them to thrive in nutrient-poor environments.
The Sticky Mechanism
The “glue plant”‘s stickiness comes from specialized glandular tentacles on its leaves. These tentacles secrete a clear, glistening, highly adhesive mucilage. This sweet-smelling substance lures and ensnares insects, trapping them upon contact.
Many sundew species, like Drosera capensis, can slowly curl their leaves or tentacles around trapped insects, increasing contact with glandular surfaces. The plant then secretes digestive enzymes (esterase, peroxidase, phosphatase, protease) to break down the insect’s soft tissues. This dissolves the prey into a nutrient-rich “soup,” allowing the plant to absorb essential nutrients like nitrogen and phosphorus, which are scarce in their natural boggy habitats.
Growing and Care
Light
Sundews need bright light for ample dew production. Most species require at least six hours of direct sunlight daily. Indoors, use a sunny windowsill with morning light or supplemental grow lights. Insufficient light leads to weak, leggy growth, poor coloration, and reduced dew.
Water
Water type is important for sundew health. These plants are sensitive to tap water minerals, which accumulate and cause harm. Use only distilled, reverse osmosis (RO), or rainwater. Keep the substrate consistently moist, often by placing the potted plant in a tray with 1-3 cm of pure water for bottom absorption.
Humidity
Sundews prefer high humidity for consistent mucilage production. Insufficient humidity is a common reason for a lack of dew, though some species adapt to lower levels. Increase humidity with a humidity tray (distinct from watering tray) or by growing plants in a terrarium.
Substrate
Sundew soil must be nutrient-poor, acidic, and well-draining, mimicking bog habitats. Standard potting soils with fertilizers will harm them. A common blend is sphagnum peat moss and an inert aggregate like perlite or rinsed silica sand, typically in a 2:1 or 1:1 ratio.
Feeding
Sundews get nutrients, especially nitrogen and phosphorus, from captured insects. Though they photosynthesize, insects provide supplementary nutrition for growth and flowering. Outdoors, they usually catch enough prey. For indoor plants or when natural prey is scarce, supplemental feeding with small insects (e.g., freeze-dried bloodworms, crushed beta fish food pellets, wingless fruit flies) every two to three weeks can be beneficial. Avoid overfeeding.
Common Varieties and Identification
The term “glue plant” refers to the diverse Drosera genus, with over 194 species. These carnivorous plants exhibit various growth habits, from flat rosettes to upright forms. A defining characteristic is their leaves covered in glistening, tentacled structures that secrete sticky mucilage.
Two popular, easy-to-grow varieties are Drosera capensis (Cape sundew) and Drosera spatulata (spoon-leaved sundew). D. capensis, native to South Africa, forms semi-erect rosettes of elongated leaves with prominent red-tipped glands. D. spatulata is a smaller, rosette-forming sundew with distinctive spoon-shaped leaves, widely distributed across Asia and Australia.
Troubleshooting Common Issues
Lack of Dew
A sundew’s lack of dew indicates suboptimal growing conditions. Common causes include insufficient light (reducing mucilage production), low humidity (causing dew evaporation), and impure water (inhibiting dew). To resolve, ensure adequate bright light, maintain high humidity, and use pure water sources.
Wilting or Drooping Leaves
Wilting or drooping leaves signal water management or root health issues. While sundews need consistently moist soil, overwatering can cause root rot and wilting due to suffocated roots. Conversely, completely dry substrate also causes wilting from dehydration. Check soil moisture, adjust watering frequency, and ensure proper drainage to alleviate symptoms.
Leaves Turning Brown/Black
Leaves turning brown or black can stem from several factors. Mineral buildup from tap water is a common culprit, as accumulated salts can burn roots and foliage. Too much direct sunlight for unaccustomed species, or sudden light changes, can also lead to browning. Some temperate sundew varieties naturally brown or die back during dormancy in cooler months.
Safety and Handling
“Glue plants” are non-toxic to humans and pets. The sticky mucilage, effective at trapping insects, is harmless on skin but can leave a minor residue.
When handling sundews, especially those with delicate tentacles, do so gently to avoid disturbing mucilage glands. Excessive touching removes dew, temporarily impairing prey capture. Mucilage on hands washes off with soap and water.