Solidago L.
Family: Asteraceae
Solidago image
Emmet J. Judziewicz  
Goldenrods are familiar late summer and autumn wildflowers easily recognized by the large inflorescences of many small golden-yellow heads. The identification of species, however, is often difficult. Most of the common wide-ranging species are highly variable. Many of the features used in keys can be altered by habitat, herbivore damage to the stem apex, hybridization, and other factors. Identification is often easier in the field where traits such as the presence of basal leaves and rhizomes, height of undamaged stems, size of clone, etc. can be observed for the whole population and "typical" characters determined. This genus of more than 100 species, all but one native to North America, has been trimmed in some treatments by the removal of the species with flat-topped (corymbiform) inflorescences. Recent studies support the transfer of the "grass-leaved goldenrods" to Euthamia, but the species sometimes placed in Oligoneuron (included in this key in the first part of couplet one) fit well in Solidago.