Alder Bushes

2016 April 23

There are clumps of these shrubs all over our property. They are alders, genus Alnus, which are moderately closely related to birch. Ours only get about ten feet tall.


Unlike a lot of other deciduous trees and shrubs, these are fairly easy to distinguish in the winter (these pictures were taken Marcy 12, 2016) because of their little, sausage-like catkins.


Here is a close-up. These are the male flowers, and in the spring they will stretch out, pop open so that they look more like the tails of tiny cats, and start shedding pollen.


The female flowers are separate, and look more like little pinecones that are about the size of a fingernail. These are actually last year’s cones, and have already spread their seeds.


When they leaf out in the summer, as in these pictures from August 30, 2014, they have heavily-ribbed leaves about the size of the palm of a person’s hand.


These are also the primary hosts of the wooly alder aphids, which make quite an infestation every year.


Most years these aphids are tended by ants, who defend them from predators in exchange for the honeydew that the aphids secrete along with their wax. Not always the same species, mind you: some years they are covered with one of our two local species of carpenter ants, and other years it is ants in the Formica genus. But last year, there were no ants and they were being defended by a mixture of yellowjackets and bald-faced hornets. I guess it is mainly a question of who has the closest nest that year, and/or who finds them and lays claim to the “herd” first.

One Response
  1. Carole permalink
    April 23, 2016

    Have read alders are a good host plant for a lot of caterpillars species, so a good plant for birds to find a meal.

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