Overview of Physcia adscendens
Physcia adscendens (Fr.) H. Olivier, commonly known as tree lichen, is a foliose lichen that belongs to the Physciaceae family. This lichen is widespread and commonly found in various parts of the world, including North America, Europe, and Asia. It is a symbiotic association between a fungus and an algal partner, which allows it to thrive in a variety of habitats, including forests, woodlands, and urban areas.
Common Names of Physcia adscendens
Physcia adscendens is known by several common names, including tree lichen, common greenshield lichen, and hoary rosette lichen. These names are derived from the lichen's ability to grow on trees and its physical appearance, which is characterized by a greenish-grey fruticose thallus and rosette-shaped lobes.
Uses and Benefits of Physcia adscendens
Physcia adscendens is not widely used for medicinal or industrial purposes. However, it can be an indicator of air pollution, as it is sensitive to sulfur dioxide levels, which are commonly associated with industrial activities. Additionally, it plays an important role in the ecosystem, as it provides food and shelter for a variety of insects and other animals.
Appearance of Physcia adscendens
Physcia adscendens has a unique appearance that makes it easy to identify in the field. It has a fruticose thallus, which means that it is a bush-like structure that branches out from a central stem. The thallus is greenish-grey in color and can grow up to 10 centimeters in diameter. The lobes of the thallus are rosette-shaped, with a white tuft of fibers at the center. The lower surface of the thallus is smooth, while the upper surface has a rough, scaly texture. Overall, Physcia adscendens is a beautiful and fascinating lichen that is an important part of many ecosystems around the world.
Light Requirements
Physcia adscendens prefers to grow in partially shaded areas. It cannot tolerate direct sunlight as it may cause desiccation of the thallus. It can grow in various light intensities ranging from low to moderate but high light intensity is inhibitory to its growth.
Temperature Requirements
The optimum temperature range for the growth of Physcia adscendens is between 15°C and 25°C. However, it can tolerate freezing temperatures and can survive even at -20°C. The extreme hot temperature limit is unknown, but reports suggest that the thallus can withstand a temperature of up to 45°C for a short time.
Soil Requirements
Physcia adscendens is a lichen that grows on the bark of trees, rocks, and soil, making it a versatile plant in terms of substrate preferences. It grows well in acidic soils, although it can survive in alkaline soils as well. The plant prefers a humid environment and grows well in soils with a pH range of 4.5-6.5.
Cultivation Methods for Physcia adscendens
Physcia adscendens is a type of lichen that grows well in areas with low air pollution. To cultivate this plant, you should first find a location with the appropriate conditions.
This plant prefers to grow in areas with a high humidity, so you should try to provide enough moisture for it to grow healthily.
Moreover, you should also provide a location with enough sunlight exposure. This plant can grow in partial shade, but it prefers to grow in areas with at least six hours of direct sunlight per day.
Ideally, you should also choose a location that is not exposed to strong winds or heavy rains, as these conditions can damage the plant's structure.
Watering Needs for Physcia adscendens
Watering is a crucial part of the cultivation process for any plant, including Physcia adscendens. However, since this plant is a type of lichen, it has unique watering needs compared to traditional plants.
Physcia adscendens absorbs water and nutrients through its thallus, which is the tissue that covers the surface of the plant. As such, it does not require regular watering like traditional plants but instead relies on moisture from the surrounding environment.
If you are growing this plant in a container, you should ensure that the soil remains evenly moist but not waterlogged. In case you notice the soil is too dry, step in and give it a light misting.
Fertilization for Physcia adscendens
Since it is a type of lichen, Physcia adscendens doesn't need regular fertilization. It obtains its nutrients from the air, water, and nutrients in the substrate.
Thus, you should avoid using commercial fertilizers as they can harm the plant, The main issue is that they can cause an increase in the amounts of rapidly growing or aggressive competing species of fungi, which might damage or even smother the lichen-forming fungi that make up the lichen.
Pruning for Physcia adscendens
Pruning is not required for Physcia adscendens since its growth isn't 'out of control' like normal plants. You can simply remove the dying or heavily soiled top layer of the thallus to keep the plant healthy and looking good.
Additionally, avoid the use of chemicals to wash the plant as they can damage its delicate structure. Instead, gently brushing or lightly blowing off any dust or debris on the surface is enough.
Propagation of Physcia adscendens
Physcia adscendens (Fr.) H. Olivier can be propagated through vegetative reproduction, which involves the use of thallus fragments.
Vegetative propagation
To propagate Physcia adscendens vegetatively, thallus fragments can be cut, using a sterilized blade, to about 1-2cm in length.
The fragments are then placed on a suitable substrate, such as moistened bark, rocks, or soil, and kept in a humid environment with moderate light exposure. The fragments will gradually grow and attach to the substrate, developing into mature thalli.
Vegetative propagation can be a quick and efficient way to establish new populations of Physcia adscendens, especially in areas where natural populations may be limited or threatened.
Disease Management for Physcia adscendens
One common fungal disease that can affect the plant is Physciella chloantha, which causes blackened patches on the thallus. To prevent this disease, it is important to maintain good air circulation around the plant and avoid watering from above. If the disease is already present, it may be necessary to apply a fungicide to the affected areas.
Another fungal disease that may occur is Pertusaria pertusa, which causes yellow to reddish-brown spots on the thallus. Infected areas should be removed and destroyed to prevent spread.
Physcia adscendens may also be susceptible to bacterial diseases such as Pseudomonas putida. Avoid overwatering and provide good air circulation to prevent infection. If the disease is already present, a copper-based fungicide may be applied to manage it.
Pest Management for Physcia adscendens
One common pest that may attack Physcia adscendens is the mite Bryobia spp. Mites can be controlled by introducing predatory mites, such as Phytoseiulus persimilis, or by applying neem oil to the plant.
Snails and slugs may also cause damage to the plant. Copper barriers or snail baits can be used to manage them.
If larger animals, such as deer, are browsing on the plant, fencing or other physical barriers may be necessary to protect it.
