Red Alder

Basic Information

Common Name: Red Alder

Scientific Name: Alnus rubra

Native Habitat: Western North America, from Southeast Alaska to Southern California, primarily along the Pacific Coast.

History / Discovery / Cultivator

Red Alder, scientifically known as Alnus rubra, is a prominent tree species of the Pacific Northwest. Its history is intertwined with both the indigenous populations and the later European settlers of the region. Long before European contact, Red Alder played a significant role in the lives of Native American tribes. They utilized the tree for various purposes, recognizing its medicinal properties. The inner bark was often used to create a red dye, providing color for textiles, basketry, and body paint. Additionally, the bark possessed analgesic and anti-inflammatory qualities, making it a valuable remedy for ailments such as skin irritations, digestive issues, and even tuberculosis. The wood, though not as durable as some other hardwoods, was used for carving, tool handles, and firewood.

The formal scientific description of Alnus rubra dates back to the late 18th century. While the exact details surrounding its initial “discovery” are somewhat ambiguous, it’s generally attributed to European botanists exploring the Pacific Northwest during this period. The name “rubra,” meaning red in Latin, clearly refers to the distinctive reddish color of the freshly exposed inner bark.

Unlike many commercially cultivated plants, Red Alder hasn’t undergone extensive selective breeding for ornamental purposes. Its primary cultivation remains focused on forestry and land management. It’s valued for its rapid growth and ability to fix nitrogen in the soil, improving soil fertility. This makes it a popular choice for reforestation projects, particularly on disturbed or nutrient-poor sites, such as clear-cut areas or after wildfires. Its ability to thrive in moist, often poorly drained soils also makes it suitable for riparian zone restoration, helping to stabilize stream banks and improve water quality.

While not heavily cultivated for ornamental use, Red Alder is increasingly recognized for its ecological value in urban environments. Its ability to tolerate a range of soil conditions and its relatively fast growth make it useful for creating urban forests and green spaces. Additionally, it provides habitat for various wildlife species, contributing to biodiversity in urban landscapes. Ongoing research continues to explore the full potential of Red Alder, not only for its ecological benefits but also for its potential in bioenergy and other sustainable applications. Its ability to thrive in challenging environments and its valuable ecosystem services are likely to ensure its continued importance in the Pacific Northwest and beyond.

Plant Care Summary

Botanical Insights

Adaptations

Red Alder exhibits several notable adaptations that contribute to its success in its native habitat. One of its most significant adaptations is its symbiotic relationship with nitrogen-fixing bacteria (specifically Frankia alni) in its root nodules. These bacteria convert atmospheric nitrogen into a form that the tree can use, allowing Red Alder to thrive in nutrient-poor soils, a common characteristic of recently disturbed areas. This nitrogen-fixing ability also enriches the soil, benefiting other plant species in the vicinity.

Another adaptation is its ability to tolerate wet and poorly drained soils. This allows it to colonize riparian zones and other areas where other tree species might struggle. The tree also exhibits rapid growth, enabling it to quickly establish itself and outcompete other plants for resources. Furthermore, Red Alder’s relatively thin bark and deciduous nature allow it to respond quickly to changes in environmental conditions.

Propagation Methods

Red Alder can be propagated through several methods:

• Seed Propagation: The most common method. Collect cones in the fall, extract the seeds, and stratify them (cold treatment) before sowing in the spring.
• Stem Cuttings: Hardwood cuttings can be taken in late winter or early spring. Rooting hormones can improve the success rate.
• Root Suckers: Red Alder readily produces root suckers, which can be carefully dug up and transplanted. This is a less reliable method than seed propagation.

Toxicology

Red Alder is generally considered non-toxic to humans and common pets like cats and dogs. While some sources mention mild skin irritation from handling fresh sap, serious adverse effects are not commonly reported. Ingestion of small amounts of bark or leaves is unlikely to cause significant harm. However, as with any plant, it’s best to avoid consumption, especially in large quantities.

Common Problems

Pests:

• Aphids
• Alder Woolly Sawfly
• Leaf Miners

Diseases:

• Alder Dieback (Phytophthora)
• Root Rot (various fungi)
• Leaf Spot (various fungi)

Other:

• Iron Chlorosis (yellowing leaves due to iron deficiency, common in alkaline soils)
• Wind Damage (susceptible to breakage in high winds, especially when young)
• Sunscald (damage to bark from intense sun exposure, especially on young trees)

Rarity & Value

Rarity:

Red Alder is not considered rare. It is a common and widespread tree species throughout its native range in western North America.

Value:

The value of Red Alder is primarily related to its timber and ecological services. It’s a commercially valuable hardwood used for furniture, cabinets, and pulpwood. Its ecological value stems from its nitrogen-fixing ability, its role in soil stabilization, and its provision of habitat for wildlife. Individual trees are not typically highly valued unless they possess exceptional size, form, or unique characteristics. However, stands of Red Alder are valued for their timber production and ecological benefits.