[1] The many goldenrod species can be difficult to distinguish, due to their similar bright, golden-yellow flower heads that bloom in late summer.

Propagation is by wind-disseminated seeds or by spreading underground rhizomes which can form colonies of vegetative clones of a single plant.

Solidago is in the family Asteraceae (formerly known as Compositae), a diverse and widespread clade containing approximately 23,000 species and 12 tribes, which inhabit all continents except Antarctica.

Related Asteraceae genera, such as Chrysoma, Euthamia, and Oreochrysum, have been included within Solidago at one point or another,[9] but morphological evidence[10][9][11] has suggested otherwise.

In a study comparing morphological characters of Solidago and related subgroups, the authors consider the subjectivity of classifying a genus and how to define it within broader tendencies concerning the taxonomy of North American Asteraceae.

However, external morphological characters such as habit, or the general appearance of the plant and how a suite of traits contribute to its phenotype; pappus size; and the point of freeing of stamen filaments from the corolla tube, are useful classification schemes for Solidago, since they are applied to differentiating between Asteraceae taxa.

[12] Based on the lack of bundle sheath extensions, it is suggested that Chrysoma, Euthamia, Gundlachia, and Petradoria should be distinct taxa and outside of Solidago.

The first molecular phylogeny based on chloroplast DNA treats Brachychaeta, Brintonia, Oligoneuron, and Oreochrysum as constituents of Solidago.

More recently, an analysis of combined ITS and ETS data provided additional support for the inclusion of Oligoneuron as part of Solidago.

[11] As mentioned, the lack of bundle sheath extensions in Euthamia compared to Solidago,[9] and deviations in floral morphology[12] present evidence for separation of these taxa.

A taxonomy of Euthamia as a genus was presented, providing a detailed description of distinguishing external morphological characters, such as fibrous-roots, sessile leaves, and mostly corymbiform inflorescences.

At the time a taxonomy of Solidago was published,[10] related taxa causing contention, such as Chrysoma, Euthamia, Oligoneuron, and Petradoria, were excluded from this genus.

[7] Although chromosome count is a useful metric for differentiating among Solidago taxa, it may be problematic due to the frequent variation in ploidy levels.

Cytogeographic patterns in the Solidago gigantea complex, with tetraploids occurring in eastern North America and hexaploids in Oregon and Washington, were observed.

[1] It was asserted that S. ptarmicoides should be united with Solidago rather than the genus Aster due to external morphological features such as similar pappus length as well as the same chromosome base (x=9).

[7] Goldenrod is considered a keystone species, and has been called the single most important plant for North American pollinator biodiversity.

[20] Goldenrods have become invasive species in many parts of the world outside their native range, including China, Japan, Europe and Africa.

[21][22] Solidago canadensis, which was introduced as a garden plant in Central Europe, has become common in the wild, and in Germany is considered an invasive species that displaces native vegetation from its natural habitat.

[26] Frequent handling of goldenrod and other flowers, however, can cause allergic reactions, sometimes irritating enough to force florists to change occupation.

Like George Washington Carver, Henry Ford was deeply interested in the regenerative properties of soil and the potential of alternative crops such as peanuts and soybeans to produce plastics, paint, fuel and other products.

[38] Ford had long believed that the world would eventually need a substitute for gasoline, and supported the production of ethanol (or grain alcohol) as an alternative fuel.

He and Ford experimented with different crops, including sweet potatoes and dandelions, eventually devising a way to make the rubber substitute from goldenrod, a plant weed commercially viable.

[46][47] Goldenrod is also used in some formulas for cleansing of the kidney or bladder during a healing fast, in conjunction with potassium broth and specific juices.

[28] In various assessments by the European Medicines Agency with respect to Solidago virgaurea, non-clinical data shows diuretic, anti-inflammatory, antioxidant, analgesic and spasmolytic, antibacterial, antifungal, anticancer and immunomodulatory activity.