How to identify Red alder (Alnus rubra)

How to identify Red alder (Alnus rubra)

Red alder, also known as Oregon alder

Red alder stands as a significant deciduous member of its family, reaching heights of 65-98 feet (20-30 meters) with a notable bark that peels in a way that exposes a distinctive orange/red hue beneath. The leaves are simple, rounded with serrated edges, and a glossy green. The catkin-like flowers give way to small, woody cones. Crucial identification includes the smooth grey bark of younger specimens that darkens and fissures with age.

Lifespan: Perennial

Plant Type: Tree

Leaf Type: Deciduous

Quickly Identify Red alder

Smooth grey bark darkening to rusty red with age.

Ovate leaves with serrated margins and revolute hairs.

Male catkins measuring 4-6 inches (10-15 cm), hang pendulously.

Triangular olive to reddish-brown twigs with pubescent scales.

Small cone-like strobiles with winged samaras for wind dispersal.

Detailed Traits of Red alder

Leaf Features

Red alder has ovate leaves that are 2.5-6 inches (6-15 cm) long, with a pointed apex. The green leaves feature serrated margins that curl under (revolute). The veins are deeply impressed, especially on the underside, which also has hairs. In fall, the leaves turn a striking yellow, adding a seasonal touch to the plant's appearance.

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Flower Features

Red alder exhibits distinct sexual dimorphism in its floral structures. Male catkins are elongated and reddish, measuring 4-6 inches (10-15 cm) in length. They hang pendulously from branches, facilitating wind pollination. Female catkins, on the other hand, are cone-like, woody, and oval-shaped, serving as crucial reproductive sites. These female structures eventually mature into seed-bearing cones. Flowers typically bloom in early spring, with male and female catkins appearing on the same tree but in separate clusters.

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Stem Features

The stems of red alder are characterized by olive to reddish-brown twigs that are triangular in cross-section. The stems feature distinctly stalked buds with 2-3 pubescent scales. Prominent lenticels are also a notable characteristic, aiding in gas exchange. The texture can be somewhat rough due to the presence of these lenticels, and the triangular shape helps in identifying the plant distinctively. Twigs generally exhibit a consistent thickness and branching pattern crucial for proper identification.

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Fruit Features

The fruit of red alder is characterized by small, cone-like strobiles, with each reaching under 1 inch (2.54 cm) in length. These woody, brown fruiting bodies persist on the branches throughout the winter season. The seeds within are crafted into winged samaras, facilitating dispersal by wind. The fruit's notable trait is the lightweight construction of the seeds, designed to glide away from the parent tree, ensuring propagation of red alder.

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Red alder and Their Similar Plants

Black alder vs. Red alder: What's The Difference?

Black alder (Alnus glutinosa) is indigenous to almost all of continental Europe. It’s used commercially in papermaking, in the manufacture of fiberboard, and in energy production. The bark of black alder has been used for hundreds of years in dyeing and tanning. The leaves of this species are so sticky, some people put them on the floor of their homes to trap fleas.

Hazel alder vs. Red alder: What's The Difference?

The hazel alder is a small tree common to the United States. It is slow growing and takes about ten years to reach maturity. It prefers the moist soil of riverbanks and creek beds. This tree or large bush bears fruit that resembles a pinecone.

Manchurian alder vs. Red alder: What's The Difference?

Found in the wild at elevations of 762 m and 1524 m, manchurian alder, is said to be the most drought tolerant Alder and can be transplanted easily. Manchurian alder is used for furniture and as building timber. It also makes for good fuel and charcoal. It has been noted as a nitrogen fixer and utilized to prevent soil erosion.

East Asian alder vs. Red alder: What's The Difference?

The tree height is 15 to 20 m and the diameter is about 60 cm. The male flower ears are a black-brown cylindrical shape that hangs down in a tail shape. The fruits are pine cones and ripen around fall. The leaves are patterned and oval with a length of 5 to 13 cm. There are fine saw blades on the edges.

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Key Facts About Red alder

Attributes of Red alder

Plant Type

Tree

Plant Height

3.5 m to 22 m

Spread

10 m

Leaf Color

Green

Flower Size

2.5 cm

Flower Color

Yellow

Green

Red

Fruit Color

Brown

Copper

Stem Color

Green

Brown

Yellow

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Scientific Classification of Red alder

Phylum

Vascular plants

Class

Dicotyledons

Order

Beeches, walnuts, and allied trees

Family

Birch

Genus

Alders

Species

Red alder (Alnus rubra)

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Distribution Map of Red alder

Red alder is a tree native to the temperate broadleaf and mixed forests of the Pacific Northwest region of North America. It has a range extending from northern California to Alaska. In addition, red alder has been introduced to South America, where it has adapted to similar environmental conditions.

Native

Cultivated

Invasive

Potentially invasive

Exotic

No species reported

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A Comprehensive Guide to Red alder How to Grow and Care for Red alder