There are around 130 species Goldenrods in two genera, Solidago and Euthamia, with about 70 species for the USA, and around 20 for Québec. A few species were introduced from Europe some 250 years ago. Solidagos are known to hybridize freely and botanists are not in agreement as to the number of species.
The genus belongs to the Asteraceae family.
Their leaves are alternate, linear to lanceolate, most often toothed, usually finely to sharply serrated, but a few species have entire leaves. The leaves are either feather-veined or with parallel veins.
The flower heads are yellow and sometimes white. They have ray florets with few rays, seldom more than ten. Groups of flower heads are often clustered on the top edge of branches near or at the top of the plant. The flowers are almost always pollinated by insects and their pollen is not carried on the wind.
Propagation is by wind-disseminated seed or by underground rhizomes. Solidagos are clonal plants which spread by both specialized underground stems called rhizomes and by seeds. Because of this vegetative growth through rhizomes, Solidagos form clumps of stems which are all genetically identical (i.e. clones). Each individual stem within a clone is called a ramet. In recently abandoned fields, it is often easy to spot the individual clones. However, in some old fields, there may be only a few clones each with thousands of ramets.
Goldenrod are used as a food plant by the larvae of some Lepidoptera species.
Unlike many other taxa, the characteristics of the flowers are often not the most important issue for identification. Shape of the inflorescence and characters of the leaves are often critical and each has its challenges. Individual inflorescences may not conform closely to the standard descriptions for a given species and stems that have been damaged during development may fail to meet expectations.
It is not necessary to collect the below-ground structures, but it is wise to collect one or more full stems, because the lower stem leaves may be of different shape and size than the upper leaves and they may be critical in negotiating the key. The lower leaves of some species may shrivel and fall off late in the growing season, making identification difficult if the broader suite of characters is not recognized. As in the collection of all plant vouchers, it is a good idea to spend a few minutes to determine that the specimens collected are representative of the population.
To compound all these difficulties, some Solidagos have conflicting common names. Many amator botanist, and even some experienced ones, are simply content to just simply call them all Goldenrods, without concerning themselves about what species each plant may be. Many of the established Latin names of Soidago species have been changing lately due to DNA and genetic research that is being done on all plants.
The following species are common in my area and somewhat easy to identify: Solidago caesia, Solidago juncea, Solidago nemoralis, Solidago rugosa and Solidago flexicaulis.
Euthamia graminifolia that was know as Solidago graminifolia and changed genus a few years ago, is also common in my area and easy to identify.
On the other hand, some species are very similar and very difficult to tell apart, e.g. Solidago canadensis vs. Solidago gigantea. But if you see a goldenrod with a ball gall it is Solidago canadensis or Solidago gigantea or Solidago altissima.
Solidagos can be used for decoration and making tea. They are, in some places, held as a sign of good luck or good fortune. Since the golden plumes of Solidagos line Kentucky's roadsides in the fall and since nearly 30 species are found there, the Solidago is the official state flower of Kentucky. It was also recently named the state wildflower for South Carolina.
British gardeners adopted Solidagos long before Americans. They only began to gain some acceptance in American gardening (other than wildflower gardening) during the 1980s. The ability of Solidagos to survive in less than perfect situations means that it can rapidly become a weed (i.e. taking up more of the garden than the gardener had planned!) when given good conditions. A hybrid with an Aster, known as x Solidaster is less unruly, with pale yellow flowers, equally suitable for dried arrangements.
Solidago canadensis was introduced as a garden plant in Central Europe, and is now common in the wild. In Germany, it is considered an invasive species that displaces native vegetation from its natural habitat.
Inventor Thomas Edison experimented with Solidagos to produce rubber, which it contains naturally. Edison created a fertilization and cultivation process to maximize the rubber content in each plant. His experiments produced a 12 foot tall plant that yielded as much as 12 percent rubber. The rubber produced through Edison's process was resilient and long lasting. The tires on the Model T given to him by his friend Henry Ford were made from Goldenrod. Examples of the rubber can still be found in his laboratory, elastic and rot free after more than 50 years. However, even though Edison turned his research over to the U.S. government a year before his death, Goldenrod rubber never went beyond the experimental stage.
There is an old legend that relates Solidagos to Asters. Two young girls talks about what they would like to do when they grew up. One, who had golden hair, said she wanted to do something that would make people happy. The other, with blue eyes, said that she wanted to be with her golden-haired friend. The two girls met and told a wise old lady of their dreams. The old lady gave the girls some magic corn cake. After eating the cake, the girls disappeared. The next day, two new kinds of flowers appeared where the girls had walked: Asters and Goldenrods.
In folk beliefs, Solidagos were thought to bring good luck when grown beside the house, and could be worn to help you meet your future love or carried to help you find lost objects! Useful as these properties may be, they are difficult to prove scientifically, whereas the physical properties of Solidagos are more tangible.
The Solidagos however has been approved by a German Commission for the treatment of bladder and urinary system inflammations. Their beneficial actions are said include increasing blood flow to the kidneys and promoting urination, without ridding the body of valuable minerals as allopathic diuretics do. Solidagos are said to be anti-inflammatory and antispasmodic and therefore calms and strengthens inflamed, painful kidneys. It will be especially appropriate where there has been a history of mild kidney infections and kidney stones or gravel. It is thought to help flush out small stones and gravel by reducing the amount of calcium that builds up in the kidneys.
The month, day and picture number might be followed by a letter:
Click on the thumbnails to get larger view. The original photos are usually in TIFF format, the photos shown are generally in JPEG format, usually of dimension one half (surface one quarter) for loading time reduction.
|Field of Goldenrods||Blooming Goldenrods||Blooming Goldenrods||Blooming of Goldenrods|
|Larvae on Goldenrods||Wasp feeding||Feeding Bumble Bee||Feeding Bumble Bee|
|Feeding Bumble Bee||Feeding larvae||Field of Goldenrods in fruits||Field of Goldenrods in fruits|