Erigeron droebachiensis O. F. Muell., Fl. Dan. 5 (15): 4, tab. 874 1782
Creators: name: Sennikov, Alexander N.
name: Kozhin, Mikhail N.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Asterales
Asteraceae
Erigeron
Erigeron droebachiensis

description: 6. Erigeron droebachiensis O.F. Müll., Fl. Dan. 5(15): 4, tab. 874 (1782)   
Erigeron acris droebachiensis - Erigeron acris var. droebachiensis (O.F. Müll.) Willd., Sp. Pl., ed. 3, 3(3): 1959 (1803) - Erigeron acris subsp. droebachiensis (O.F. Müll.) Mela, Lyhyk. Kasvioppi Kasvio, ed. 1: 66 (1877).   
Erigeron acris angustatus = Erigeron acris var. angustatus Hartm., Handb. Skand. Fl., ed. 1: 315 (1820) - Erigeron acris subsp. angustatus (Hartm.) Fr., Novit. Fl. Suec. Mant. III: 107 (1843) - Erigeron acris f. angustatus (Hartm.) Fr., Summa Veg. Skand. 1: 183 (1846). Type. [icon] Flora Danica, tab. 874 (1782) (lectotype designated here).  
Type.  
 [icon] Flora Danica, tab. 874 (1782) (lectotype designated here). Fig. 9. Epitype (designated here): Norway. Ringerike, 05.07.1892, J. Dyring (H 1642568). Fig. 10.   
Description.  
Stems 30-70 cm tall, branched in the upper third, green or slightly purple-coloured, sparsely covered by numerous hairs 0.5-1 mm long in the basal third or nearly glabrous. Cauline leaves 12-20 under the synflorescence, sparse or slightly congested, gradually reduced towards the stem top, middle and lower ones covered by numerous hairs 0.3-0.8(1) mm long on both sides or along margins only. Synflorescence with rather short branches carrying few to several capitula, racemose in shape, branches glabrous or with solitary hairs 0.3-0.4 mm long. Phyllaries 5.5-6 mm long, slightly or moderately purple-coloured, outer and middle ones sparsely covered by hairs 0.5-1 mm long at base or on the basal half, innermost ones glabrous. Ray flowers pink. Pappus greyish-white.  
Flowers in July, fruits in August.  
Distribution in Murmansk Region.  
Apatity industrial area (Fig. 8B).  
Global distribution.  
Boreal and Hemiboreal zones of Fennoscandia and Eastern Europe, southern limit unknown.  
Nomenclatural note.  
 The species name is derived from Drøbak, now a town in Viken County, Norway, which is the original locality of the species (Müller 1782). This derivation implied the Latinisation of this place name as “Droebachia”, from which “droebachiensis” is produced by analogy with e.g. “hafniensis” that was derived from “Hafnia”, i.e. Copenhagen (Stearn 1966). The species epithet “droebachiensis” is therefore grammatically correct and cannot be changed to “droebachensis” as used in PoWO (2023), which would imply a different Latinisation as “Droebachum”. No original herbarium collections of Erigeron droebachiensis have been traced in Denmark (Ryding, pers. comm.) and Norway (Salvesen, pers. comm.). The only extant original element on which the species name was based is the illustration published in the protologue (Müller 1782). We agree that the original plant described by Müller was a glabrous taxon with corymbose synflorescences occurring as native in Fennoscandia, which was recognised in a similar way by other modern researchers (Tzvelev 1994; Kurtto and Väre 1998). Tzvelev (2001) attempted to radically change the application of the name E. droebachiensis, which he suggested to apply to a hybrid between E. acris s.l. and E. canadensis L., otherwise known as E. × huelsenii  Vatke (Seregin 2015b). This erroneous application affected some Russian collections and literature (Seregin 2005, 2010, 2015a) but gained no recognition elsewhere. Although we agree with Olander and Tyler (2017) that the original illustration of E. droebachiensis unambiguously represents the species, its identity is far from apparent to those who are not familiar with the Erigeron acris group in Scandinavia. This is evident by the gross misinterpretation of this illustration by Tzvelev (2001), and by the uncertainty expressed by Šída (1998). To avoid further doubts and debates, we formally designate the illustration as a lectotype of E. droebachiensis, and support this illustration by an epitype collected in Ringerike, a traditional district situated at the distance of 50 km from Drøbak. The epitype specimen is nearly glabrous, except for the basal part of stems and capitula, and also leaf margins. A larger plant of this specimen agrees with the original illustration in a branched paniculate synflorescence, long leaves and long-exserted ligules. A smaller plant attached to the same sheet agrees with the larger plant in the pubescence and represents its reduced variant with unbranched stems, shorter leaves and a raceme-like synflorescence. Erigeron acris var. angustatus Hartm. was described (Hartman 1820) without any original locality indicated in the protologue. One diagnostic character of this variety (small stalked flowering heads) indicated the racemose synflorescence; the second character (larger apical capitulum) was derived from the diagnosis of E. droebachiensis. Subsequently Hartman (1838) explicitly noted that this variety corresponds to E. droebachiensis, whose illustration (but not the name itself) was cited in the protologue, and we designate this illustration as the lectotype of Hartman’s variety. Fries (1843b) elevated this variety to the subspecies level, thus creating the earliest available name at this rank.   
Taxonomic note.  
 The distribution of Erigeron droebachiensis outside Fennoscandia is partly obscured due to its common confusion with other taxa of the E. acris group. Šída (1998) presumed that this species may turn to be identical to E. macrophyllus Herbich, which occurs in Central and Southern Europe, although the latter is characterised by more numerous and dense cauline leaves, which are 20-45 in number (Tzvelev 1994; Šída 2001).
description: Published as part of Sennikov, Alexander N. & Kozhin, Mikhail N., 2023, Taxonomic revision of the Erigeron acris group (Asteraceae) in Murmansk Region, Russia, reveals a complex pattern of native and alien taxa, pp. 83-128 in PhytoKeys 235 on page 83, DOI: 10.3897/phytokeys.235.111020