12 Species of Alder Trees for Your Yard

Growing Tips and Identifying Alder Species

Black alder tree with thin branches with bright green leaves and small buds

The Spruce / Evgeniya Vlasova

Alder trees and shrubs (Alnus spp.) are fast-growing and usually deciduous in nature. The 30 members of the genus are classified in the Betulaceae family, which is more commonly known as the birch family. The thin bark and light wood of the alder tree make it obvious that this tree belongs with other Betulaceae species. Alder trees are good for many uses, ranging from building structural foundations, to making fine guitars, to providing wood chips used to flavor smoked meats. The fruiting parts of the tree are edible, and substances within the bark have been used to create cancer-fighting drugs. Few trees offer more useful versatility than the alder.

The most notable features of all varieties of alder trees are their catkins and strobiles. Both male and female flowers (catkins) appear on the trees. As a monoecious species, alders self-pollinate. Female flowers begin developing as small, round green growths in the summer or fall before the next spring's bloom. Yellowish male flower clusters form into 1.2 to 3.9-inch slender, dropping cylinders, releasing their pollen in early spring (January-April). The plant is wind pollinated. When the female flowers are pollinated, they mature into small cones (called strobiles). Though the majority of alder tree species are deciduous, these trees resist the brilliant autumn color change of most other deciduous species. Green leaves simply turn brown and fall from the tree as it prepares for dormancy.

Since these trees are able to fix nitrogen in the soil, they can grow in less than fertile areas. Plants with nitrogen fixation capabilities form symbiotic relationships with bacteria that allow them to improve the soil on recently cleared land, for example. In the case of ​alders, it is with the Frankia bacteria. This quality allows them to grow in landscaping areas where other plants may struggle. They typically grow well in moist areas, such as along riverbanks.

Alders make excellent hosts for many moth and butterfly larvae, plus birds are attracted to the strobiles. The flowers attract pollinators, but the male flowers may cause allergy sufferers discomfort with the profuse pollen they produce.

Alder Tree Identification

Alder trees as a genus can be fairly easily distinguished from similar trees by inspecting various features:

  • Leaves: Young leaves are sticky to the touch and are very shiny. Mature leaves will have a rounded shape with notched edges, not the pointed tips found on birch trees. The leaves tend to turn brown rather than vibrant yellow or red in the fall.
  • Flowers: These are elongated catkins rather than blossoms. They appear in early spring. Male catkins are long and turn yellow with pollen. Female catkins are much shorter, purple in color, and gradually transform into cones containing seeds.
  • Bark: All species have grayish, rough bark that develops fissures as the tree trunk expands. These trees lack the papery bark found in birches.
  • Habitat: Alders are naturally found in wetland areas and along rivers.

Spotting small differences within these features will help you identify specific species within the genus. Here are 12 common alder trees and shrubs for your landscaping needs.

  • 01 of 12

    Black Alder (Alnus glutinosa)

    Black alder tree branch with rounded and ribbed leaves with small green strobiles closeup

    The Spruce / Evgeniya Vlasova

    The black alder gets its common name from the dark grey color of the bark in aged trees. Its Latin name, Alnus glutinosa, tips you off that this tree develops a gummy resin on new leaves and buds. Take note that this alder species can become invasive in some areas. If you prefer the look of leaves that are dissected (divided into many sections), look for the 'Laciniata' and 'Imperialis' cultivars.

    • Native Area: Europe, Northern Africa, and Western Asia
    • USDA Growing Zones: 3 to 7
    • Height: 40 to 60 feet
    • Sun Exposure: Full sun to part shade
  • 02 of 12

    Green Alder (Alnus viridis)

    green alder (Alnus viridis)
    RvFf / Getty Images

    The green alder is one of the smaller species and is a large shrub or small tree. Its shiny green leaves have a yellow hue. While most other alder trees flower before producing leaves, this variety sends out its leaves before the catkins appear.

    There are several different subspecies of green alder found throughout the world, including: Alnus viridis subsp. crispa (sometimes seen as A. crispa), A. viridis subsp. fruticosa, A. viridis subsp. viridis, A. viridis subsp. maximowiczii (sometimes A. maximowiczii), A. viridis subsp. sinuata, (sometimes A. sinuata) and A. viridis subsp. suaveolens.

    • Native Area: North America, Europe
    • USDA Growing Zones: 3 to 7
    • Height: 6 to 14 feet
    • Sun Exposure: Full sun to part shade
  • 03 of 12

    Gray Alder (Alnus incana)

    alder, Alnus incana
    Danler / Getty Images

    Also known as speckled alder or mountain alder, this species is commonly seen in the Rocky Mountains of North America. These alder trees have smooth, gray bark and the underside of the leaves also has a gray appearance. While most other alder trees produce yellow catkins, this tree has reddish-purple catkins that appear each spring.

    • Native Area: Europe and North America
    • USDA Growing Zones: 2 to 6
    • Height: 20 to 35 feet
    • Exposure: Full sun to part shade
  • 04 of 12

    Hazel Alder (Alnus serrulata)

    Alnus Serrulata, the hazel alder or smooth alder blooming
    Jarmila Horalkova / Getty Images

    This species is either a shrub or a small tree. It tends to clone itself through suckers, forming a dense thicket of alders if left unchecked. The species name serrulata refers to the margins of the leaves, which are toothed. Also known as tag alder or swamp alder, these trees need consistently moist soil conditions and are most often found near a water source, like a river or stream. These alder trees are most prevalent in the eastern part of North America.

    • Native Area: North America
    • USDA zones: 4 to 9
    • Height: 10 to 20 feet
    • Exposure: Full sun to part shade
    Continue to 5 of 12 below.
  • 05 of 12

    Italian Alder (Alnus cordata)

    Italian alder tree Alnus cordata male catkins and shaped leaf
    Whiteway / Getty Images

    Native to Mediterranean locations in southern Italy or off the coast of France, this stately tree and its rounded leaves are an attractive choice for landscaping. The species name cordata tips you off that this has cordate—or heart-shaped—leaves. It's a recipient of the Award of Garden Merit from the Royal Horticultural Society and grows well in poorly drained soil conditions. However, it also fares better in drier soil conditions than some other species of alder trees. Considered to be a medium-sized alder tree with top heights around 50 feet, it can occasionally grow to 80 feet.

    • Native Area: Corsica, Southern Italy
    • USDA zones: 5 to 7
    • Height: 30 to 50 feet
    • Exposure: Full sun
  • 06 of 12

    Red Alder (Alnus rubra)

    Pacific Northwest forest and Red alder tree
    Craig Chanowski / Getty Images

    If you are in the Pacific Northwest, the red alder is the hardwood that you are most likely to come across. For this reason, it's aptly known as the Pacific Coast alder or Oregon alder. You can identify this species from the others in the genus by the fact that the margins of the leaves curl under. The bark can be used to make different colors of natural dyes.

    Interestingly, Fender has used red alder as the hardwood of choice for its electric guitars since the 1950s. The acoustic properties, plus the fact that it was abundantly available on the west coast near Fender headquarters, made it a natural choice.

    • Native Area: North America: Pacific coast, southeast Alaska, British Columbia, Washington, Oregon, Southern California, Northern Idaho
    • USDA Zones: 4 to 7
    • Height: 40 to 80 feet
    • Exposure: Full sun
  • 07 of 12

    Seaside Alder (Alnus maritima)

    seaside alder

    Robert H. Mohlenbrock / USDA-NRCS PLANTS Database

    Also known as a beach alder, the name is a bit of a misnomer since these trees are found in northeastern coastal regions but never on the coast. It's worth pointing out that populations of seaside alders are also known to exist in Oklahoma, which is baffling considering the tree's more common native region of Maryland, Delaware, and Georgia. Interestingly, the seaside alder blooms in the fall, while most of the other alder species produce flowers in the spring. An alternative Latin name for this species is Alnus metroporina. There are three different subspecies of the seaside alder: subsp. georgiensis, subsp. oklahomensis and subsp. maritima.

    • Native Area: North America
    • USDA zones: 4 to 7
    • Height: 20 to 30 feet
    • Exposure: Full sun
  • 08 of 12

    White Alder (Alnus rhombifolia)

    white alder

    Don Loarie / Flickr / CC BY 2.0

    The white alder grows at a fast pace to about 30 feet in height, before slowly creeping towards its full maturation of 50 feet. Some of the tallest specimens of this species have been known to reach 100 feet. The tree gets its common name from its bark color, which ranges from white to gray. It's a good choice if you have a soggy spot in your yard or garden and it has deep green leaves with a fresh fragrance.

    • Native Area: North America
    • USDA Zones: 8 to 11
    • Height: 30 to 50 feet
    • Exposure: Full sun to part shade
    Continue to 9 of 12 below.
  • 09 of 12

    Japanese Alder (Alnus japonica)

    Japanese alder (alnus japonica)

    Marina Denisenko / Getty Images

    Japanese alder trees are native to Japan. Korea, and parts of China. This small variety of alder grows quickly to a mature height of 12 to 25 feet. It features a dense canopy of slender, oval-shaped green leaves. Usually deciduous, in some climate zones Japanese alder is evergreen in nature. Like other alder specimens, it does well in nutrient-deprived soil or wet conditions.

    • Native Area: Asia
    • USDA Zones: 5 to 7
    • Height: 40 to 60 feet
    • Exposure: Full sun
  • 10 of 12

    Mexican Alder (Alnus jorullensis)

    Mexican alder (Alnus jorullensis)

    Auckland Museum / Wikimedia Commons / CC BY 4.0

    The Mexican alder is an evergreen or semi-evergreen tree or shrub, often used for ornamental landscaping. Its most eye-catching feature is its vivid green leaves with deeply serrated edges. These trees are considered to develop an invasive root system, so choose a planting location where the roots won't interfere with plumbing or structural aspects of your home. Check with your local extension office to make sure it's not classified as an invasive species in your area.

    • Native Area: Central America: Honduras, Guatemala, Mexico
    • USDA Zones: 7 to 12
    • Height: 65 to 80 feet
    • Exposure: Full sun
  • 11 of 12

    Oriental Alder (Alnus orientalis)

    Oriental alder (Alnus orientalis)

    Michael Kurz / Wikimedia Commons / CC BY-SA 3.0

    For a fast-growing shade tree, consider the Oriental alder. This variety, also known as the Syrian alder, reaches its mature height of 25 to 50 feet in as little as a decade. The wedge-shaped leaves are dark green, glossy, and feature a small-toothed margin. Don't confuse this tree with the Japanese alder; the orientalis variety hails from the coastal Mediterranean region of Turkey.

    • Native Area: Cyprus, Iran, Lebanon-Syria, Palestine, Turkey
    • USDA Zones: 7 to 9
    • Height: 25 to 50 feet
    • Exposure: Full sun
  • 12 of 12

    Himalayan Alder (Alnus nitida)

    Himalayan Alder alnus nitida

    Krzysztof Ziarnek / Wikimedia Commons / CC BY-SA 4.0

    The Himalayan alder is native to the Himalayan mountains and Pakistan. This tree is known for its useful applications, including providing dye or hardwood for furniture-making. The bark is also said to have anti-inflammatory properties and a variety of herbal remedies exist using this and other alder species.

    • Native Area: Pakistan, western Himalayas, Nepal
    • USDA Zones: 7 to 10
    • Height: 65 to 80 feet
    • Exposure: Full to part sun

The alder tree family includes smaller shrubs and towering trees. Regardless of the size and species you select, these trees are sure to thrive in wet, soggy soil that might be a challenge for other species. If you're looking for other fast-growing shade trees, consider maple or elm trees.

Article Sources
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  1. Black Alder. University of Minnesota

  2. Alnus cordata | italian alder/rhs gardening.