Two species of invasive goldenrods, Solidago canadensis and
Solidago gigantea, are spread over all territories of
Lithuania. Solidago × niederederi, a putative hybrid
between S. canadensis and native Solidago
virgaurea, was found in 27 populations mixed with the parental
species. This research represents the characterization of S. ×
niederederi in comparison to the other mentioned
Solidago species, with the use of one-way analysis of
variance (ANOVA), principal-components analysis (PCA), and discriminant
analysis of a large data set. Twenty quantitative, four qualitative, and
five ratio morphological and anatomical characteristics, pollen viability,
and somatic chromosome numbers of the four Solidago species
were studied with the aim to ascertain inter- and intraspecific variation
and reliable features identifying S. × niederederi, and to
test the hypothesized hybrid origin. The PCA of morphological and anatomical
characteristics showed the clear intermediate position of S. ×
niederederi compared to S. canadensis and
S. virgaurea. The results showed that the most
informative characteristics for the distinction of hybrids from parental
species are floral traits such as the lengths of the disc, ray florets, and
involucre. The intermediate stomatal characteristics and sharply decreased
pollen viability discovered herein could potentially be used as an
additional discriminating character in Solidago hybrid
identification and support the hybrid origin of S. ×
niederederi.