Erigeron

Farhani, Tayyebeh, Kazempour-Osaloo, Shahrokh, Zare-Maivan, Hassan & Mozaffarian, Valiollah, 2018, Evolutionary history of the tribe Astereae in the Flora Iranica area: Systematic implications, Phytotaxa 379 (1), pp. 95-117 : 111

Eurasian Erigeron

In the Flora Iranica area 15 species of Erigeron were listed, whereas only five species, including E. annus as a weed, were recognized in Iran ( Grierson & Rechinger 1982, Tavakkoli & Ghahremaninejad 2008). All the species are classified into two sections, Trimorpha (Cass.) M. Pop. (represented by E. acris L.) and Erigeron . Our analyses of the datasets revealed that 22 sampled taxa of Erigeron (from North America and Eurasia) formed a highly supported clade. Within this clade, species of Eurasian Erigeron constituted a subclade derived from the basal North American congeneric species. This result is in agreement with the nrDNA ITS analyses of Noyes (2000).

Erigeron acris is widely distributed in temperate regions of Eurasia to North America ( Nesom 2008, Pliszko 2015). This species consists of annual, biennial or perennial plants with trimorphic flowers within each capitulum, i.e. outer female ray flowers with an erect filiform lamina, inner female ray flowers without a lamina, and typical inner bisexual disc flowers ( Grierson & Rechinger 1982, Nesom 2008). It is very variable in morphological features especially in indumentum, number of cauline leaves, and arrangement of capitula, and is divided into 10 subspecies ( Greuter 2003, Pliszko 2015) represented by six subspecies in the Flora Iranica area, three of which are restricted to Iran ( Grierson & Rechinger 1982). This species is distinct because of its trimorphic flowers within each capitulum, i.e. outer female ray flowers with an erect filiform lamina, inner female ray flowers without a lamina, and typical inner bisexual disc flowers ( Nesom 2008). The species at the current status appears to be non- monophyletic, two accessions of which (from Turkey and France) along with E. borealis (Vierh.) Simmons form a trichotomy being sister to E. uniflorus , whereas four out of six subspecies recognized in Flora Iranica ( Grierson & Rechinger 1982) are placed in a distinct subclade along with a couple of other Eurasian Erigeron . Apparently, these subspecies should be treated at the species rank, yet a comprehensive phylogenetic analysis with more plant sampling is needed to assess their exact taxonomic status. The same situation occurred for E. uniflorus . The species has a widespread distribution in most alpine and arctic areas across the northern hemisphere. It is represented by two subspecies in Iran, E. uniflorus subsp. daenesis and subsp. elborensis ( Grierson & Rechinger 1982) . On the basis of our molecular data together with the morphological characteristics (indumentum of peduncles with some glandular hairs in addition to spreading hirsute and smaller weak adpressed hairs, as well as slightly larger capitula with involucres 10–18 mm wide ( Vierhapper 1906, Grierson 1975), these two are distinct from the typical E. uniflorus L. and should be considered as independent species which retain their species ranks. Indeed, the former has been treated in Flora of Turkey as a distinct species ( Grierson 1975). We here resurrect, hence, these two subspecies at the species rank E. daenensis Vierh. and E. elborsensis Boiss.