Erechtites hieraciifolius

Trotta, Italy Giacomo, Castello, Miris, Petruzzellis, Francesco, Pischedda, Sara & Boscutti, Francesco, 2023, Short communication First record of naturalization of Erechtites hieraciifolius (L.) Raf. ex DC. (Asteraceae) in Italy, Natural History Sciences 10 (2), pp. 77-79 : 77-79

Erechtites hieraciifolius (L.) Raf. ex DC. (≡ Senecio hieraciifolius L.) ( Asteraceae ) is a therophyte native to the Americas,introduced as medicinal or ornamental plant or unintentionally to Asia, Europe, and the Pacific region

1 Dipartimento di Scienze della Vita (DSV), Università degli Studi di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italia.

2 Dipartimento di Scienze Agrioalimentari, Ambientali e Animali (DI4A), Università degli Studi di Udine, Via delle Scienze 99, 33100, Udine, Italia.

* Corresponding author: [e-mail]

© 2023 Giacomo Trotta, Miris Castello, Francesco Petruzzellis, Sara Pischedda, Francesco Boscutti

Received for publication: 11 September 2023

Accepted for publication: 16 September 2023

Online publication: 11 October 2023

( Barkley, 2006; Darbyshire et al., 2012; Rojas-Sandoval, 2022). It is rapidly spreading in Europe as a new alien species in many eastern countries (Gudinskas & Taura, 2020; Dudáš et al., 2022; Kaplan et al., 2023; Štech et al., 2023). Reports of its occurrence have emerged from Germany, Austria, Slovenia, Croatia, Bosnia-Herzegovina, Serbia, Czechia, Slovakia, Poland, Romania, and Hungary; it is considered invasive in Czechia, Hungary, and Poland ( Greuter, 2006 +; Zaniewski et al., 2020; Rojas-Sandoval, 2022; Pladias, 2014+).

In North America it mainly occurs in deciduous and mixed forest areas, but it grows also in rocky open woods, eroded slopes, thickets, waste ground, wetlands, fields and along roadsides and railroads ( Steyermark, 1963; Britton & Brown, 1970; Barkley, 2006; Darbyshire et al., 2012). It is a pioneer species associated with major disturbances, such as forest fires (common name: American burnweed, fireweed), but it is also common in disturbed forest edges and in stands affected by wind-throws. The species pre- fers shade and moist conditions ( Neal et al., 2023), but shows a considerable phenotypic variability, since it col- onizes areas with different soil nutrient content, moisture, pH and salinity ( White et al., 2017).

The first record in Europe dates to 1876 in Croatia ( Kornhuber & Heimerl, 1885). The species remained rare until the beginning of the 2000s, when it showed a fast spread, especially along an east to west direction. It becomes a weed with an expansion possibly related to climate change or extension of its ecological amplitude, as well as to an increase in fire frequency ( Zaniewski et al., 2020). Most records in Europe are related to forest clearings, but it has been found also in open-canopy for- ests, man-made habitats, disturbed sites, waste grounds, exposed bottoms of fishponds and flower beds (see e.g. Kaplan et al., 2023).

Erechtites hieraciifolius is an annual species, up to 100-200 cm tall with an erect stem, simple or branched above, and alternate, ovate-lanceolate to lanceolate, sessile leaves up to 20 cm or more long, with irregularly coarsely toothed to coarsely lobate-dentate margins ( Fig. 1a ). Reproduction is by seeds, which are mainly dispersed by wind. The germination is enhanced by soil disturbance, including fire ( Neal et al. 2023). It has economic impacts being a serious weed of crops and mixed pastures. Thanks to its fast growth, large size and abundant production of seeds it can outcompete other species, with negative impacts on native biodiversity and modification of succes- sional processes (Rojas-Sandoval, 2022).We found E. hieraciifolius during fieldwork carried out in July-Septem- ber 2023 in the western Classical Karst (Friuli Venezia Giulia, FVG, North-East Italy) near the border between Italy and Slovenia, in areas affected by large fires in July 2022, within burnt karstic thermophilous mixed Quercus pubescens Willd. subsp. pubescens woodland and Pinus nigra J.F.Arnold subsp. nigra plantations. It was found with other neophyte and ruderal species dominant in the burnt areas, e.g. Erigeron canadensis L., E. sumatrensis Retz. , and Senecio inaequidens DC.

The plants were identified according to Tutin (1976), Barkley (2006), Haines (2011), and Neal et al. (2023).

Specimina visa ( Fig. 1b ): Doberdò del Lago (Gorizia), fraz. Jamiano , burnt area of karstic mixed oak woodland, WGS84: 45.818251N, 13.591968E, 81 m a.s.l., 31 July 2023, F. Boscutti, M. Castello, G. Trotta ( TSB); Duino-Aurisina (Trieste), fraz. Medeazza, burnt area of karstic mixed oak woodland, WGS84: 45.801258N, 13.5932914E, 123 m a.s.l., 16 August 2023, G. Trotta, F. Boscutti ( MFU); Doberdò del Lago (Gorizia), fraz. Jamiano, burnt area of karstic mixed oak woodland, WGS84: 45.812900N, 13.572080E, 52 m a.s.l., 22 August 2023, S. Pischedda (Field observation); Doberdò del Lago (Gorizia), loc. Gola Gorica (near Sablici, Gorizia), burnt Black pine plantation, WGS84: 45.807360N, 13.585337E, 90 m a.s.l., 8 September 2023, M. Castello (Field observation) .

We observed few individuals in each site (from 3 to 12). Most individuals were adult. Plant height was 80-137 cm; all individuals had abundant flowers and fruits. We propose E. hieraciifolius as a naturalized alien species new for the flora of Italy.

The species was found in burnt forest sites, but always in rather or light shaded conditions while it was never found in fully burnt open sites (scrubland or grassland) nor unburnt sites. It seems to prefer moist forest soils. Based on the features of this pioneer species and field observations, we consider E hieraciifolius a plant with a high invasive potential.

In the past, it was recorded in an urban garden in the lowlands of the FVG region in the municipality of Codroi- po (Udine), some 60 km away from the present location. (F. Martini personal communication), with an uncertain status of cultivated or escaped plant.

After its appearance, connected to the wildfires of 2022 in the Karst, there may occur an ongoing or future dispersion in other burnt areas or other types of disturbed sites, forest clearings and edges. Considering this, our data suggest that further research should be undertaken in the near future to better understand its colonization and expansion mode. We also suggest possible early eradication actions, bearing in mind that manual eradication of this annual weed is particularly easy.

Figures

Fig. 1 - Flowering individual and typical flower head of Erechtites hieraciifolius (L.) Raf. ex DC. recorded in a burnt wood stand in Jamiano (Friuli Venezia Giulia, Italy) (a). The distribution of the population currently known is also reported (b). / Individuo in fiore e capolino tipico di Erechtites hieraciifolius (L.) Raf. ex DC. trovato in un bosco incendiato a Jamiano (Friuli Venezia Giulia, Italia) (a). Si riporta anche la distribuzione delle popolazioni attualmente note (b). (Photo / Foto: Francesco Boscutti).