Speckled Alder


The Speckled or Gray Alder (Alnus incana rugosa) is a common wetland small tree or large shrub here in Maine.  It usually occurs in moist soils though it can grow in nearly any location.  Most often the plant is seen as a series of small trunks about 4″ to 7″ in diameter arising from a common root system and growing 10 to 15 feet high.  The trees can grow singly and become taller, to 30 ft.  It is named speckled for the many light-colored gas exchange pores in the bark called lenticels.  The alder figures in the life stages of the woolly aphid, an insect I discussed earlier in this blog.ald3

Beyond the use to woolly aphids, the alder is valuable to the environment as a pioneering shrub in disturbed areas, for erosion control along waterways, and for its ability to fix nitrogen in the soil.  Because alder withstands having its roots flooded, it is often found along the very edges of streams.  Here it helps hold the soil to maintain stream banks.  After a fire or man-induced destruction of tree land, alder is among the earliest volunteers, helping to hold the soil and provide habitat for wildlife.  Many songbirds eat the alder’s seeds and the leaves and twigs are browse for herbivores.  Butterfly caterpillars also feed on the leaves.

Thanks to a symbiotic relationship with actinomycete soil bacteria, alder form large root nodules, sometimes as big as a human fist, filled with bacteria that acquire nitrogen from the soil and make it available to the plant.  The alder feeds the bacteria with the sugars it produces by photosynthesis.  This nitrogen fixing activity enriches the soil in that area for other plants much as legumes do in hayfields and gardens.

Because it is punky, the wood of speckled alders has no real use for humans beyond it’s humus forming value. But the catkins of the shrub are often used.  The male catkins are long and narrow and female catkins are shaped very much like tiny conifer cones, especially pine cones.  The male catkins are visible in the background of the first photo above.


The female catkins are woody and tough.  Being 1/2″ long or smaller, the tiny cones are desirable for many purposes including jewelry making, decorative crafts and potpourri. They contain large amounts of fine seeds that are usually shaken free before the catkins are used in crafts.ald4 These miniature cones are often fashioned whole into earrings and pendants.   A mold can also be created using a cone which is then burned away.  The resulting mold cavity is filled with silver or gold to produce solid metal jewelry.  I have a lovely little solid sterling “pine cone” pendant given to me by my husband.

In winter I collect the female catkins for sale in my online stores.  These popular craft supplies are another product helping provide cash flow for the farm.



2 thoughts on “Speckled Alder

  1. Remember when we cleared them from the field we planted to Scotch pine? They are a pest sometimes, hard to get rid of, but also a part of the ecosystem.

  2. I clearly recall when newly married to your father spending hours hauling alders he cut. There were so many of them at the campsite. They blocked the views of the water. We piled them in big stacks and they were left there. They are probably still there. Glad to hear they are so valuable for collecting nitrogen to give other trees a chance to get established. I do not remember them with great affection.

Comments are closed.