A Nitrogen Fixing Pioneer Species

If you are looking for a shining example of the intricate relationships between all the elements of an ecosystem, Alnus serrulata (Smooth or Common Alder) is it!

This nitrogen-fixing shrub can help an area recover from flooding, logging, mining or almost any disturbance.  All it needs is moist or wet soil and some sun.  It will provide itself with all the nitrogen it needs, so thrives in the poorest of soils.   As it grows, the soil is gradually improved and becomes receptive for other plants.

Ecosystem Wildlife Value

Alder attracts a particular aphid (yes,  aphids are part of the ecosystem!) which is food for the larvae of our carnivorous butterfly, the Harvester.  Tiger swallowtail, pallid tiger swallowtail, white admiral, green comma, and mourning cloak also rely on Alder for larval food.  To top it off, Alder also supports goldfinches and grouse.

Birds help spread plants by moving seed around, and the alder — by attracting birds — plays an important role in getting new seed to the area.  This increases the diversity of plant species, helping the area support even more birds, butterflies, pollinators, and wildlife.

Erosion Control

You don’t need a disturbed site to appreciate the alder, though.  They are excellent at erosion control on streambanks.  This sturdy shrub is heat and humidity tolerant and will even grow in up to 3 feet of water.

Alders form a fine-branched thicket and produce attractive catkins that dangle in the breeze in late winter andearly spring..  The male catkins are longer and the female catkins are short and stubby, resembling pine cones.  The female catkins remain on the shrub for up a year and provide an interesting visual appeal.  If you are looking to tidy up its appearance, it can be rejuvenated every few years by cutting to 6” from the ground.

Our container grown alders will transplants readily,  even into saturated soils.  Stop in today!