Azores Seaside Goldenrod
Solidago azorica Hochst. ex Seubert is native to the Azores and possible introduced into Bermuda. It has been treated as S. sempervirens var. azorica (Hochst. ex Seubert) St. John and as S. sempervirens subsp. azorica (Hochst. ex Seubert) Semple. It can be similar to S. sempervirens or technically similar to so forms of S. uliginosa but with more leafy stems. The leaves are often much broader than those of S. sempervirens, sometime even being ovate or broadly elliptic.
Two studies support treating S. azorica as a separate species. Schaefer (2015) reported that plants of S. azorica from the Azores differed in their nuclear ITS and ETS sequences plus a number of microsatellite markers from plants of S. sempervirens from North America. Semple et al. (2016) found strong support for treating it as a species in a multivariate study of the S. sempervirens complex. Solidago azorica presumably was introduced by long distance dispersal into the Azores from coastal northern North America plants sufficiently in the past for divergence to have occurred; Schaefer (2015) noted that records indicate is was likely present in the Azores in pre-Columbian times. The alternative is that humans introduced it relatively recently and founder effect and selection resulted in divergence rapidly; molecular and morphological studies indicate this is not the most likely scenario. The species is diploid 2n=18.