Origin
Betula nana L. ssp. exilis (Sukatschev) Hultén commonly known as dwarf birch is a small and hardy woody shrub that belongs to the genus Betula and family Betulaceae. The plant is native to the Arctic and subarctic regions of Europe, North America, and Asia. It is widely distributed across the northern hemisphere and is found in alpine, subalpine, and arctic tundra habitats having a good level of cold adaptation.
Common Names
The plant goes by many common names such as dwarf birch, bog birch, Arctic birch, western dwarf birch, and Greenland dwarf birch. In the Inupiaq language of Alaska, it is known as Ugamaga while in Siberia it is called "????????? ???????."
Uses
Betula nana L. ssp. exilis has several uses. It is a popular ornamental plant commonly used in rock gardens and landscaping designs. In some parts of North America, it is also grown as a ground cover plant. Besides its aesthetic value, the plant also has medicinal properties as it contains betulinic acid, which has been shown to have antitumor and anti-inflammatory action. Additionally, the leaves and twigs of dwarf birch have been historically used to make tea, and the bark has been used for tanning leather, making baskets, and as fuel.
General Appearance
Betula nana L. ssp. exilis is a deciduous shrub that grows up to 1-1.5 meters tall. The stems are slender, reddish, and hairy when young, but become grayish-brown and scaly with age. The leaves are dark green, oval, and pointed, and grow up to 2.5 cm long. The underside of the leaves is covered with small white hairs that give it a silky texture. The flowers are greenish-yellow and hang in catkins that bloom in spring. The fruits are small, winged nutlets that ripen in late summer and fall. The plant has a shallow root system and grows in dense colonies, forming important habitats, especially in the arctic tundra environment.
Light Requirements
Betula nana L. ssp. exilis grows best in full sun or partial shade. It can tolerate some shade but too much shade can result in poor growth and spindly plants. Thus, it is recommended to plant them in a location that receives at least six hours of direct sunlight daily.
Temperature Requirements
Betula nana L. ssp. exilis is a hardy plant that grows well in cool to cold climates. It can tolerate temperatures as low as -50 degrees Fahrenheit (-45 degrees Celsius) and can be found in USDA zones 1-7. In warmer climates, it may require some shade or protection from the hot afternoon sun to prevent wilting or scorching.
Soil Requirements
Betula nana L. ssp. exilis thrives in moist, well-drained, acidic soils. It prefers soils with a pH range of 4.5 to 6.5 and can tolerate some waterlogging. The plant is adapted to grow in poor quality soils such as sandy or rocky soils. However, it can also grow in loamy or clay soils with good drainage. It is recommended to amend poor quality soils with peat moss or compost to improve soil structure and fertility.
Cultivation Methods for Betula nana L. ssp. exilis (Sukatschev) Hultén
Betula nana L. ssp. exilis (Sukatschev) Hultén, commonly known as dwarf birch, is a plant that requires specific growing conditions for survival. This plant thrives in cool and moist environments and is found naturally in the Arctic and subarctic regions of the world. It can, however, be grown indoors or outdoors under certain conditions.
If you plan to cultivate dwarf birch indoors, be sure to provide it with partial to full exposure to sunlight. These plants grow slowly and prefer well-drained acidic soil with pH levels ranging from 4.0 to 6.0. For outdoor cultivation, it is recommended to plant the tree in the early spring when the soil is still moist and well-drained. Shadier areas are preferable for this purpose, as the plant prefers partial sunlight.
Watering Needs for Betula nana L. ssp. exilis (Sukatschev) Hultén
Watering is a crucial aspect of caring for Betula nana L. ssp. exilis (Sukatschev) Hultén. These plants require consistent moisture, and the soil should never be allowed to dry out completely. Overwatering, on the other hand, can cause root rot and should be avoided. To check if your plant needs watering, poke your finger about an inch into the soil. If it feels dry, it's time to water the plant. During the growing season, you should water the plant once a week or whenever the soil feels dry, but reduce the frequency during winter.
Fertilization of Betula nana L. ssp. exilis (Sukatschev) Hultén
As dwarf birch is a slow-growing plant, it does not require regular fertilization. A light application of a balanced slow-release fertilizer once every spring should suffice. Overfertilization can cause the plant to become weak and susceptible to pests and diseases. Always make sure to follow the instructions on the fertilizer package and use recommended concentrations.
Pruning of Betula nana L. ssp. exilis (Sukatschev) Hultén
Pruning of dwarf birch is generally not required unless you want to shape the plant or in cases where there are dead or diseased branches. Prune during late winter or early spring before new growth begins. To prune, use sharp and clean pruning shears to cut back the branches. Removing more than a third of the plant can damage the tree, and it can take several years for the tree to recover.
Propagation of Betula nana L. ssp. exilis
Betula nana L. ssp. exilis, also known as dwarf birch, is a low-growing deciduous shrub that is widely distributed across the Arctic region. The plant is typically propagated through vegetative methods such as cuttings, layering, and division.
Cuttings
Propagation through cuttings involves taking a stem or branch from the parent plant and allowing it to grow new roots and shoots, creating a genetically identical clone. For Betula nana L. ssp. exilis, softwood cuttings are best taken in late spring or early summer when the plant is actively growing. The cuttings should be about 4-6 inches long and taken from the tips of healthy, disease-free branches. The cuttings can then be dipped in rooting hormone and planted in a well-draining rooting medium.
Layering
Layering is another propagation method that involves creating a new plant by encouraging roots to grow from a stem that is still attached to the parent plant. For Betula nana L. ssp. exilis, layering can be done by bending a low-growing stem to the ground and covering it with soil. The stem should be secured in place with a U-shaped stake or a rock. Over time, roots will form at the point where the stem touches the soil, and a new plant will emerge.
Division
Propagation through division involves separating an established clump of plants into smaller sections, each of which can become a new plant. For Betula nana L. ssp. exilis, division can be done in early spring or fall. The clump should be carefully dug up and the roots teased apart, ensuring that each section has a healthy root system and several shoots. The new plants can then be replanted in well-draining soil.
Disease Management
Betula nana L. ssp. exilis is generally a hardy plant that can resist many diseases. However, some diseases may still affect it:
- Birch rust: Caused by Puccinia spp. fungus, this disease causes yellow spots on leaves. Birch rust can be controlled by pruning and removing infected parts.
- Leaf spots: This disease is caused by various fungi, including Marssonina betulae and Septoria betulae. It manifests as small brown lesions on leaves that can merge and kill the whole leaf. This can be managed by removing and destroying infected leaves and maintaining good air circulation.
- Canker: This disease is caused by fungi and bacteria and can lead to small sunken lesions on the bark. Infected areas should be removed and treated with fungicides or bactericides.
Pest Management
Betula nana L. ssp. exilis can also be subject to some pests:
- Birch leafminer: The larvae of Fenusa pusilla feed on leaves, causing brown patches. This can be prevented by maintaining healthy trees and using insecticides.
- Alder aphid: Euceraphis betulae sucks sap from plant tissue, leading to weakened plants and sooty mold. Pruning can help, and using insecticidal soap and neem oil can deter aphids.
- Birch skeletonizer: The larvae of Bucculatrix canadensis feed on leaves, causing brown patches that lead to defoliation. This can be prevented by using insecticides or introducing natural predators like parasitic wasps.
