About 100 perennial species make up the genus Solidago (Goldenrod), most being found in the meadows and pastures, along roads, ditches and waste areas in North America. There are a handful of species from each of Mexico, South America, and Eurasia. Some American species have also been introduced into Europe some 250 years ago.
Many species are difficult to distinguish. Probably due to their bright, golden yellow flower heads blooming in late summer, the goldenrod is often unfairly blamed for causing hay fever in humans. The pollen causing these allergy problems is mainly produced by Ragweed (Ambrosia sp.), blooming at the same time as the goldenrod, but is wind-pollinated. Goldenrod pollen is too heavy and sticky to be blown far from the flowers, and is thus mainly pollinated by insects.
Goldenrods are easily recognized by their golden inflorescence with hundreds of small capitula, but some are spike-like and other have auxiliary racemes. They have slender stems, usually hairless but S. canadensis shows hairs on the upper stem. They can grow to a length between 60 cm and 1.5 m. Their alternate leaves are linear to lanceolate. Their margins are usually finely to sharply serrated.
Propagation is by wind-disseminated seed or by underground rhizomes. They form patches that are actually vegetative clones of a single plant.
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Goldenrods can be used for decoration and making tea. Goldenrods are, in some places, held as a sign of good luck or good fortune; but they are considered weeds by some.
In the garden, Goldenrod is a companion plant, playing host to some beneficial insects, repelling some pests.
nventor Thomas Edison experimented with goldenrod to produce rubber, which it contains naturally. 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.
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