Origin and Common Names
Polychidium dendriscum (Nyl.) Henssen is an epiphytic lichen that is commonly known as the "Christmas wreath lichen" or "green shield lichen." It belongs to the Parmeliaceae family of lichens and can be found in many parts of the world.Appearance
This lichen has a unique appearance with a circular to irregularly shaped thallus that is flat to slightly convex. It can grow up to 20 cm in diameter and has a lobed or wrinkled appearance. The color of the thallus varies from light green to dark olive green when wet, and it turns pale gray when dry. The upper surface of the thallus has numerous round to elongated outgrowths that make it appear somewhat lumpy. The underside is black and has root-like structures called rhizines.Uses
Polychidium dendriscum is not widely used for medicinal or commercial purposes. However, like other lichens, it is a sign of clean air and has been used as a bioindicator to monitor air pollution levels. The thallus is also a source of food for some animals, such as reindeer and caribou. It is also commonly used in Christmas decorations because of its unique appearance and green coloration.Light Requirements
Polychidium dendriscum (Nyl.) Henssen thrives in moderate to bright indirect light. It should not be exposed to direct sunlight, as it may cause leaf burn. This plant is best placed near a north or east-facing window to receive proper light and should be shielded from harsh afternoon sun.
Temperature Requirements
Polychidium dendriscum (Nyl.) Henssen prefers moderate to cool temperatures ranging between 50°F to 75°F (10°C to 24°C). It should be kept away from any drafts or extreme temperature fluctuations, as this may cause the leaves to wilt and turn yellow. It is important to maintain a consistent temperature range for this plant to thrive.
Soil Requirements
Polychidium dendriscum (Nyl.) Henssen grows best in well-draining soil that is rich in organic matter, with a pH range between 5.5 and 6.5. It also requires good aeration to prevent root rot. A high-quality potting mix that contains perlite, vermiculite, and peat moss is ideal for this plant. Avoid using heavy clay soils or soils that do not allow proper drainage.
Cultivation Methods for Polychidium dendriscum
Polychidium dendriscum is a lichen often found growing with moss on trees. It may be grown indoors in containers or outside in a suitable location. Growing it outdoors for a beginner may seem challenging, and it is suggested starting with indoor cultivation by following the steps below:
- Fill a container with a suitable growth medium such as sphagnum moss.
- Place the lichen on top of the medium and press it down gently to make sure it contacts the medium.
- Add just enough distilled or rainwater to dampen the medium, keeping it moist but not too wet.
- Place the container in a bright and cool location but out of direct sunlight.
- Ensure adequate air circulation, but avoid exposing lichen to extreme conditions. It may take some time, but the lichen will start to grow in a few weeks.
Once the lichen has established itself indoors, it may be transplanted to an appropriate outdoor location.
Watering Needs
Polychidium dendriscum is accustomed to moist environments and must be kept damp. Making use of distilled or rainwater, give it just enough water to keep its growth medium damp, but not too wet. Overwatering may damage the lichen, so be sure to keep the soil below the growth medium dry to avoid water sitting in the container.
Fertilization
Polychidium dendriscum is a lichen that obtains its nutrients from the surrounding air and atmosphere. As a result, it does not require any fertilization or feeding.
Pruning
When cultivating Polychidium dendriscum, it is important to understand that unlike a plant, lichens do not require pruning. However, they can be tidied up by gently removing any dead or discolored portions of the lichen. Remember that overhandling may damage the lichen, so avoid pruning or handling it unnecessarily.
Propagation of Polychidium dendriscum
Polychidium dendriscum is a type of terrarium plant that can thrive in moderate humidity and low light conditions. The plant can be propagated using different methods like spore propagation, vegetative propagation, and division.
Spore propagation
Spore propagation is a common method used to propagate Polychidium dendriscum. To do this, you need to gather mature spores that have been released by the plant. The spores are then sprinkled over a pre-moistened growing medium in a petri dish. The dish is covered to create a humid environment that aids spore germination. The plant gradually grows from these spores over time.
Vegetative propagation
Another propagation method used for Polychidium dendriscum is vegetative propagation. With this method, cut shoots are taken from the parent plant and grown on a moist growing medium. The cuttings have to be kept at moderate humidity and low light conditions before fresh plant growth emerges. This method is very reliable on healthy plants.
Division
The simplest method to propagate Polychidium dendriscum is division. The overgrown plant is carefully removed from its pot and divided into several individual plants. Each divided plant has to be potted and kept receiving proper humidity and light conditions, and the new plants will grow over time. This method works well on mature plants that have outgrown their pots or when the plant needs to be rejuvenated.
Disease Management
Polychidium dendriscum is not commonly affected by diseases. However, fungal infections may occur in the plant under certain conditions. The most common fungal disease is leaf spot caused by the fungus Mycosphaerella. This disease causes small, circular spots on the leaves, which may become brown and necrotic over time. To manage this disease, it is important to remove and destroy infected leaves, and keep the plant free from stress factors such as poor airflow and high humidity.
Another fungal disease that may affect the plant is root rot caused by the fungus Phytophthora. This disease causes the roots to rot, resulting in stunted growth, wilting, and ultimately death of the plant. To manage this disease, it is important to avoid over-watering the plant, ensure proper drainage, and use well-draining soil.
Pest Management
Polychidium dendriscum is not commonly affected by pests. However, if grown indoors, the plant may become infested with spider mites, mealybugs, and scale insects. Spider mites are small, sap-sucking pests that may cause yellowing and wilting of the leaves, and produce webbing on the plant. Mealybugs are white, cotton-like insects that may also cause yellowing of the leaves, as well as stunted growth and wilting. Scale insects are small, circular pests that attach to the stems and leaves of the plant, sucking the sap and causing yellowing of the leaves.
To manage these pests, it is important to regularly inspect the plant for signs of infestation and take immediate action. Infested parts should be removed and destroyed, and the plant should be treated with insecticidal soap or neem oil. It is also important to improve the growing conditions of the plant, such as increasing humidity and ensuring proper watering and fertilization, to prevent future infestations.
