Goldenrod

Goldenrod

Goldenrod patch
All photos by Jim Mason

Common Name:
Goldenrod

Scientific Name:
Solidago sp.

Provides for:
Many species of insects

One of the last big flower shows each year is provided by the goldenrods. Within Kansas 12 species are known with several varieties. They are all perennials with large clusters of small yellow flowers that appear from the end of summer until frost. The leaves of goldenrods are simple, lance or egg shaped and usually have a toothed margin. Most species propagate by a spreading root system in addition to seed. They can be a troublesome addition to a wildflower garden for that reason. They become more common in pastures under heavy grazing pressure and so are used as an indicator species by range managers.

Just about every insect with an interest in flowers may by found on goldenrod in autumn. The predators of those insects will be found there also. Wheel bugs and flower crab spiders, in particular, like to lay in wait for prey on goldenrod clusters. In the picture, a couple of blister beetles are nosing around amongst the blossoms, probably grazing on pollen. Often the visiting insects will use the occasion to get acquainted with each other and breeding will be observed. The yellow and black goldenrod soldier beetles will frequently be seen in pairs on goldenrod.

Goldenrod with beetles

Goldenrod gets mistakenly blamed for the agonies of hay fever sufferers in autumn. It blooms at the same time as ragweeds (Ambrosia sp.), which are the real culprit. Ragweeds are pollinated by the wind. Using the wind to fertilize your flowers is a very chancy business. Only by releasing billions of pollen grains into the wind can they ensure that some will find their way to the female flower of another ragweed plant and produce seed. Because they are not pollinated by insects, ragweed does not need visually attractive flower parts. They are an inconspicuous green color. People suffering from allergies in September look for a flower to blame and goldenrod gets the rap because it is so visible and abundant. The pollen grains of goldenrod, as is true of all insect-pollinated flowers, are comparatively fat and sticky so that they will adhere to visiting insects and be transferred by them to another flower. In order for a person to be affected by goldenrod pollen, they would have to stick their nose right into the flower just like a bee would!

A casual observer will notice swollen lumps on the stems of goldenrods. Some will be round and others will be football-shaped. These are called galls and they are the homes of two different types of insects that are parasites on the goldenrod. Gall-making insects may be found on a wide variety of plants, but each species of insect is specific to a given species of plant and their galls have a characteristic and recognizable shape and location. The insect larva receives protection from most predators by living within the gall and it uses the inside of the gall for food.

The round ones are home to the larval stage of the goldenrod stem gall fly (Eurosta solidaginis). In an undisturbed field one can usually find the previous year's galls along with this year's, so you can compare an inhabited one to an empty one. Carefully cutting a new one open will reveal the maggot in a chamber in the center of the gall. That is, unless it was previously discovered by a certain small beetle which specializes in burrowing into the galls and eating the hapless inhabitant! The surviving larvae finish their metamorphosis the following spring and emerge to find a mate and start the cycle anew.

The oblong ones were home to the larval stage of a moth (Gnoremoschema gallaesolidaginis). The moths emerge in late summer through a hole at one end of the gall. They mate and lay eggs in the foliage near the base of the plant. The larva overwinters and burrows down the stem of the new growth the following spring to make a new gall.

The yellow of goldenrod makes a pleasant scene with the varied bronzes, russets, oranges and purples of the fall prairie. It is a sure sign that the first frosts of winter are not long away.

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- This page was spun by Jim Mason -

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