The Australian and New Guinean everlasting paper daisy genus Xerochrysum, widely grown around the world as Strawflower, Everlasting or Immortelle, was recently revised. The first and type species, Xerochrysum bracteatum, was described in 1803 as Xeranthemum bracteatum from a plant cultivated in the Empress Joséphine's garden at Malmaison. During our project, we learned that Xerochrysum was naturalised in St. Helena, the place of Napoleón Bonaparte's last exile, and is presumed to have been introduced by him. We conducted genetic analyses to test the derivation of the St. Helena plants. Comparisons with some colourful hybrid cultivars and naturally occurring populations in Australia found the St. Helena plants to be most similar to Xerochrysum bracteatum s. str. of the Sydney Basin. The St. Helena plants were without admixture of another species as would be expected if they were more recently escaped ornamental cultivars. Our results support the conclusion that the St. Helena Xerochrysum were introduced during Napoleón's exile, likely as a reminder of his wife's garden.

Golden everlasting paper daisies in the genus Xerochrysum Tzvelev are iconic Australian native plants grown worldwide. The X. bracteatum species complex has been regarded as taxonomically confusing and in need of revision for over 60 years. We applied morphological and molecular analyses to delimit species, detect common ancestry among populations, and identify putative hybrids in the genus Xerochrysum (Asteraceae: Gnaphalieae). Multiple lines of evidence provided strong support for the recognition of new taxa. Here we describe the following 11 new species: X. andrewiae T.L.Collins & J.J.Bruhl, X. berarngutta T.L.Collins & I.Telford, X. copelandii J.J.Bruhl & I.Telford, X. frutescens J.J.Bruhl & I.Telford, X. gudang T.L.Collins & J.J.Bruhl, X. hispidum T.L.Collins & I.Telford, X. macsweeneyorum T.L.Collins, X. murapan T.L.Collins & I.Telford, X. neoanglicum J.J.Bruhl & I.Telford, X. strictum T.L.Collins, and X. wilsonii T.L.Collins, reinstate Helichrysum banksii A.Cunn. ex DC. (as X. banksii (A.Cunn. ex DC.) T.L.Collins & I.Telford), lectotypify X. banksii and X. papillosum (Labill.) R.J.Bayer, and recircumscribe X. bicolor (Lindl.) R.J.Bayer to include X. halmaturorum Paul G.Wilson and some populations of X. bracteatum sens. lat. from mainland South Australia and Victoria. We also provide revised descriptions of all taxa in the genus, their conservation status, a dichotomous key, tables distinguishing closely related taxa and distribution maps.

Golden everlasting paper daisies (Xerochrysum, Gnaphalieae, Asteraceae) were some of the earliest Australian native plants to be cultivated in Europe. Reputedly a favourite of Napoléon Bonaparte and Empress Joséphine, X. bracteatum is thought to have been introduced to the island of St Helena in the South Atlantic during Napoléon's exile there. Colourful cultivars were developed in the 1850s, and there is a widely held view that these were produced by crossing Xerochrysum with African or Asian Helichrysum spp. Recent molecular phylogenetic analyses and subtribal classification of Gnaphalieae cast doubt on this idea. Using single-nucleotide polymorphism (SNP) data, we looked for evidence of gene flow between modern cultivars, naturalized paper daisies from St Helena and four Xerochrysum spp. recorded in Europe in the 1800s. There was strong support for gene flow between cultivars and X. macranthum. Paper daisies from St Helena were genotypically congruent with X. bracteatum and showed no indications of ancestry from other species or from the cultivars, consistent with the continuous occurrence of naturalized paper daisies introduced by Joséphine and Napoléon. We also present new evidence for the origin of colourful Xerochrysum cultivars and hybridization of congeners in Europe from Australian collections.