Solidago virgaurea

European Goldenrod, "virga aurea", verge d'or européenne, Europäische Goldrute, золотарник, etc.

Solidago virgaurea L. is the nomenclatural type species of the genus.  In the broad sense, it has included nearly all taxa native to Eurasia and thus would be the species of goldenrod native to China and Japan and adjacent countries.  In the narrow sense followed here, the name has been applied to the larger headed western members of S. ser. Solidago, the S. virgaurea complex of Europe and possibly the mountains of northeastern Pakistan, northern India and Nepal.  In some Russian floristic literature, the species extends all the way across Russia to Sakhalin Island. Juzepcsuk's treatment in the Flora of the U.S.S.R. (1959; English translation 1999, Smithsonian) split S. virgaurea and S. dahurica into 14 species plus S. pacifica.  The segregates are probably ecotypical variants that may or may not warrant infraspecific level recognition.  Juzepcsuk noted that S. virgaurea was quite polymorphic in terms of leaf shape and size, inflorescence branching pattern, and in the number and size of involucres. Juzepcsuk did restrict the species to plants with entirely pubescent fruits. 

In the recent English edition of the Flora of China,  Chen and Semple (2011) limited the application of name S. virgaurea to plants mostly from Europe and mountains of south central Asia.  Solidago dahurica, S. decurrens, and S. pacifica were treated as separate species native in China.  Semple (2013), in a paper describing Solidago nipponica, continued this restricted application of the name S. virgaurea, excluding it from Japan.  As defined here S. virgaurea has fruits that are generally rather hairy with hairs distributed over the entire fruit body.  A few nearly hairless fruits have been observed in collections from western Europe. Most distinct of the European members of ser. Solidago is S. litoralis, which is densely hairy on the stems and leaves unlike any other species in subsect. Solidago.

Solidago virgaurea is highly variable in stem height in Europe.  Northern and alpine plants can be only 10 cm tall while I have seen a cultivated collection (orig. Hungary) that was nearly a meter tall.  European literature divides the species into multiple subspecies or varieties.  No attempt is made here to deal with these infraspecific taxa because I have not seen any of the infraspecific variants in the field and have not examined sufficient numbers of herbarium specimens to determine what are the range limits of the proposed morphological variants.

In a multivariate morphometric study of S. sect. Solidago and the putatively related S. sect. Multiradiatae (Semple et al. 2020), the S. virgaurea a priori group was weakly supported in the analysis of 11 species (52% assignment of specimens a posteriori to S. virgaurea) that placed heavy weighting on the total number of hairs on the fruit body, a trait most varied in S. virgaurea.  In the analysis of just S. virgaurea, S. dahurica, and S. decurrens, much higher statistical support was obtained for the S. virgaurea a priori group (87% assignment a posteriori to S. virgaurea) with the greatest weight again placed on the total number of hairs on the fruit body.  Some sparsely hairy fruits occur in plants scattered across western Europe and these were weakly assigned to S. virgaurea or to other species not considered to be present in Europe.  A few specimens of S. virgaurea from the disjunct portion of the range in the Himalaya Mts. were assigned to S. virgaurea with high probability while others were not including a cluster that included a mixture of specimens assigned a priori to S. dahurica and S. virgaurea.  Semple et al. (2020) indicated that molecular research was needed to confirm the identity of specimens from the India and Nepal with hairy fruits.  Were these all just variants of S. dahurica or were some disjunct individuals of S. virgaurea.  Semple et al. (2020) also noted the need for a large scale molecular study of S. virgaurea s.s. to determine which of the many proposed infraspecific taxa might warrant recognition.   Small scale regional studies have been inconclusive in resolving whether or not all of the dwarf alpine ecotypes belonged in a single subspecies or separate species or were just a series of independently derived higher elevation ecotypes of the more lowland and widely distribution S. virgaurea.  Semple et al. (2020) did find support for recognizing the narrow sand dune endemic S. litoralis.  A polygenomic molecular approach is needed combined with a multivariate study to find diagnostic morphological traits that distinquish the molecular groups found to be sufficiently distinct to warrant recognition at the species or variety level.  Such a study may be beyond the scope of a Ph.D. dissertation.