Goldenrod along the Sweet Marsh near my home
in northeast Iowa. USA
One of the last big flower shows each year is provided by the goldenrods. There are at least 12 species 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 gets mistakenly blamed for the agonies of hay fever sufferers in autumn. It blooms at the same time as ragweeds 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!