Hedypnois rhagadioloides (Asteraceae; Cichorieae): An alien plant found at Busan New Port
Article information
Abstract
The alien plant Hedypnois rhagadioloides (L.) F. W. Schmidt was found at Busan New Port. The genus Hedypnois Mill, to which this species belongs, is a new record in the flora of the Republic of Korea; it is related to the genera Hypochaeris L. and Picris L. Hedypnois but can be distinctly distinguished from these two genera by its pappus, which consists of scale-like bristles. Additionally, during fruiting, plants of this genus exhibit an inflated and ridged peduncle, and its inner phyllaries become hardened, curved, and envelop the outer cypselae. The cypselae have shallow longitudinal ridges and scales on their surface. This study provides photographs of H. rhagadioloides along with descriptions of the genus and species, as well as identification keys based on morphological research.
INTRODUCTION
Tribe Cichorieae, which was previously referred to as Lactuceae, is a large tribe within the subfamily Cichorioideae of Asteraceae (Kilian et al., 2009). This tribe contains approximately 1500 species, most of which are distributed in the Northern Hemisphere (Thompson, 2007; Kilian et al., 2009). Cichorieae plants are often known as weeds commonly found in urban areas, cultivated fields, and wetlands, and they are easily recognizable by their mostly spineless stems and yellow flowers in their natural habitats (Thompson, 2007). They are also morphologically characterized by abundant milky latex, zygomorphic flowers composed of ligulate florets in heads, and ligules with five toothed at the apex (Lack, 2007; Thompson, 2007; Kilian et al., 2009; Orchard, 2015).
The genus Hedypnois Mill, one of the genera in the Cichorieae, is notable for its pappus consisting of scales or scale-like hairs, distinguishing it from other related genera (Kilian et al., 2009; Enke et al., 2012; Orchard, 2015). This feature is considered to represent a reverse evolution, with the scaly pappus having branched from the primitive plumose pappus of Cichorieae (Kilian et al., 2009). There are four Hedypnois taxa globally, all of which are known to originate from the Mediterranean region and nearby areas of Southwest Asia (Thompson, 2007; Orchard, 2015; POWO, 2024). In addition to their native regions, Hedypnois taxa have been introduced to various countries, including the United States, Peru, and Australia. In the Korean flora, there are no records of this genus to date (Korea National Arboretum, 2024a, 2024b; POWO, 2024). Instead, two related genera are found in the Republic of Korea: Hypochaeris L. and Picris L. (Korea National Arboretum, 2024a, 2024b).
This study reports the alien plant Hedypnois rhagadioloides (L.) F. W. Schmidt, discovered at Busan New Port, located in the border region between Changwon-si and Busan, during a 2023 field survey of alien plants. It provides descriptions of the genus and species, along with photographs and an identification key. The results are expected to provide fundamental data for identifying this genus and species and for developing future management plans for alien plants.
MATERIALS AND METHODS
Relevant literatures were referenced to clearly identify and describe this species, as well as to provide the taxonomic key. The specimens housed in the herbaria (B, IRVC, LA, LINN, PI, SBBG) and the materials collected during field surveys from 2023 to 2024 were used for the observation of external morphology and for trait measurement using an electronic Vernier caliper (Mitutoyo 500-196-30 Absolute Digital Vernier Caliper, Tokyo, Japan). Photographs of the species were captured with a digital camera (Nikon D810, Nikon 105 mm AF Micro-Nikkor, Tokyo, Japan), and the external morphology of the cypselae was observed and photographed using a microscope (Carl Zeiss Microscopy GmbH, Stemi 508, Zeiss, Göttingen, Germany) equipped with an Axiocam ERc 5s. All the plants used for observation and measurement are preserved as voucher specimens in the herbarium of the Korea National Arboretum (KH) (Fig. 1). The terminology regarding plant morphology used in this paper follows that of Beentje (2010)
Voucher specimen of Hedypnois rhagadioloides (KH).
RESULTS AND DISCUSSION
Hedypnois Mill., Gard. Dict. Abr., ed. 4.: 606, 1754.
Korean name: 금혼초아재비속(Geum-hon-cho-a-jae-bi-sok).
Herbs annuals, hispid with anchor or simple hairs. Stems procumbent or erect, mostly branched. Leaves predominantly basal, leaf margin entire or pinnatilobed. Heads cymose or solitary, bracteate, pedunculate; peduncle ridged and inflated at fruiting; involucre cylindrical, biseriate; outer phyllaries shorter than inner phyllaries; inner phyllaries hardened and convex at fruiting, enveloping outer cypselae; receptacles flat, pitted, glabrous, epaleate. Florets ligulate, ligules oblanceolate, apex 5-lobed, yellow; stamen 5; pistil 1. Cypselae homomorphic; tetra-cylindrical, without beak, ribbed, scales; pappus dimorphic; scales or scale-like bristles.
Hedypnois rhagadioloides (L.) F. W. Schmidt, Samml. Phys. Aufsätze Böhm. Naturgesch. 1: 279, 1795; Hyoseris rhagadioloides L., Sp. Pl.: 2: 809, 1753; Hyoseris cretica subsp. rhagadioloides (L.) Arcang., Comp. Fl. Ital., ed. 2: 732, 1894; Hedypnois cretica subsp. rhagadioloides (L.) Täckh. & Boulos, Publ. Cairo Univ. Herb. 5: 29, 1974; Leontodon rhagadioloides (L.) Enke & Zidorn in Organisms Diversity Evol. 12: 14, 2012.—TYPE: LINN 957.9 (lectotype: designated by Nordenstam, 1977, Photo!).
Korean name: 금혼초아재비 (Geum-hon-cho-a-jae-bi).
English name: Cretan Hedypnois (GBIF.org, 2024).
Herbs annuals, usually up to 20 cm tall, hispid with eglandular, anchor, or simple hairs. Stems erect or prostrate, usually branched, spreading, sparsely hispid. Leaves basal and cauline; predominantly basal, alternate, sessile; basal leaves persistent, blade oblong to oblanceolate, apex acute, base attenuate, amplexicaul, hispid, 4.4–8.3 cm long, 0.8–1.9 cm wide, margin pinnatifid or entire, ciliate; cauline leaves blade oblong to oblanceolate, apex acute, base subcordate, amplexicaul, hispid, 2.8–5.5 cm long, 0.4–1.2 cm wide, margin entire, ciliate. Heads cymose or solitary, bracteate, pedunculate; bract subtending peduncle, blade linear, apex acute, base subcordate, amplexicaul, hispid, 1.2–3.3 cm long, 0.1–0.5 cm wide, margin entire, ciliate; peduncle hispid, ridged and inflated at fruiting; involucres cylindrical, biseriate, 3–6 mm in diameter; outer phyllaries 6–8, linear to lanceolate, hispid, 2–3 mm long, margin hyaline; inner phyllaries 8–10, linear to lanceolate, hispid, 8–10 mm long, margin hyaline, hardened and convex at fruiting, enveloping outer cypselae; receptacles flat, pitted, glabrous, epaleate. Florets bisexual, bilateral, ligulate; ligule limb oblanceolate, apex 5-toothed, 7–9 mm long, yellow with red to purple teeth abaxially or not; stamens 5, yellow; pistil 1, yellow, style pubescence with pale hairs. Cypselae homomorphic; tetra-cylindrical without beak, 5–6 mm long, curved, slightly and longitudinally ridged, scabrous scales along the ridges; outer achenes enveloped in hardened and curved inner phyllaries; pappus dimorphic; outer pappus scales fused to form teeth or a crown-like, 0.3–0.5 mm long, pale brown; inner pappus scalelike bristles, usually with 5 longer ones and several shorter ones, lanceolate, 7–9 mm long, scabrid-barbellate, pale brown.
Origin: Mediterranean, Southwestern Asia.
Introduced: Australia, England, Germany, Poland, South Africa, Southwestern United States, Uruguay, Korea (Changwon-si).
Specimens examined: GREECE. Epirus: Thesprotia, 19 Jun 2021, E. Willing, R. Willing 303698 (B: B 10 1255182).
ITALY. Sicily: Messina, 19 Apr 2022, J. Franzoni, A. Giacò, L. Pinzani, J. Franzoni s.n. (PI: PI 061874). Tuscany: Livorno, 6 May 2024, H. Öhm s.n. (PI: PI 066240).
USA. California: San Diego, 28 Apr 2020, J. Rebman, M. Mulligan 36494 (SBBG: SBBG 243325). Orange, 18 Jun 2020, G. Michael, R.V. Simpson, G. Kyle, B. James 4610 (IRVC: IRVC 113673). Los Angeles, 19 Mar 2019, J. Rebman, S. Vanderplank, K. O’Connor, B. Munson 35285 (SBBG: SBBG 180665); 22 Aug 2021, A.E. Baniaga 1000 (LA: LA 00645395). Ventura, 18 Mar 2022, C. M. Guilliams, K. Hasenstab-Lehman, 7055 (SBBG: SBBG 244157); 10 May 2023, R. Burgess, E. Dean 11873 (SBBG 249380).
KOREA. Gyeongsangnam-do: Changwon-si, 11 Apr 2023, S.W. Lee LSW2023037 (KH: KHB 1648842); 27 May 2024 E.S Kang, A. Cho HR24052273 (KH: KHB 1648840); 12 Jun 12, E.S. Kang, Y.K. Jung HR2406122 (KH: KHB 1648841).
Taxonomic note: Hedypnois, along with related genera Hypochaeris and Picris, shares the common characteristic of having cypselae with a pappus composed of bristles rather than plumose hairs (Lack, 2007; Kilian et al., 2009; Enke et al., 2012; Korea National Arboretum 2024a, 2024b). However, this genus can be easily distinguished from the two genera by its unique external morphology during fruiting (Fig. 2F–H). The most distinguishing feature is that its two types of pappus consist of scale or scale-like bristles instead of feathery ones (Sell, 1976; Vasil’chenko, 2001; Lack, 2007; Thompson, 2007; Orchard, 2015) (Figs. 2H, 3). This genus is also characterized by its inflated and ridged peduncle (Fig. 2F), hardened and inwardly curved inner phyllaries that envelope the outer cypselae (Fig. 2G), and cypselae that are slightly and longitudinally ridged and covered with short scales (Fig. 2H) (Sell, 1976; Vasil’chenko, 2001; Lack, 2007; Thompson, 2007; Orchard, 2015).
Photographs of Hedypnois rhagadioloides. A. Habitat. B. Stem. C. Leaf and bract. D. Involucres. E. Flower. F, G. Fruit (F. Peduncle. G. Inner phyllary and outer cypsela.). H. Cypselae (left is outer cypsela and right is inner cypsela).
Comparative photographs of the cypselae from Hedypnois rhagadioloides and related genera in the Republic of Korea. A. H. rhagadioloides. B. Hypochaeris radicata. C. Picris hieracioides subsp. japonica.
Among the taxa of Hedpnoids, H. rhagadiloides can be distinguished by its rough hairs on the inner phyllaries and its strong inward curvature during the fruiting (Fig. 2D, F–G) (Sell, 1976; Vasil’chenko, 2001; Lack, 2007; Thompson, 2007; Orchard, 2015). This species predominantly grows in sandy loam or clay soils in dry regions (Orchard, 2015).
In the Republic of Korea, H. rhagadioloides was discovered at Busan New Port in Jinhae-gu, Changwon-si. Initially, around 10 individuals were observed growing around the street trees. However, it later spread to roadsides, between sidewalk blocks, and in the gaps of building marble, with the population gradually increasing to about 30 individuals occupying an area of 150 m2. While it currently shows no invasive behavior in Korea’s natural ecosystem, its potential impact due to future spread and climate change remains uncertain. Therefore, it is necessary to evaluate the adaptation and potential spread of this species in the Republic of Korea with thorough monitoring.
Considering the habitat characteristics of H. rhagadioloides and the surrounding environment of the discovered location, it is presumed that the seeds of this species were unintentionally introduced during the sand laying process for sidewalk installation. Research on H. rhagadioloides and other recently reported alien plants (Kang et al., 2022; Lee et al., 2024) suggests that various alien plants are often introduced during the sand and gravel laying processes associated with road or building construction. Therefore, it is advisable to exercise caution regarding the introduction of invasive plants in areas where such activities are carried out.
Key for identification of Hedypnois and related genera in Korea
1. Heads peduncle uninflated and non-ridged at fruiting; involucres multi-seriate, inner phyllaries constant at fruiting, not enveloping outer cypselae; cypselae rugose or transversely ridged; pappus bristles.
2. Plants hispid with simple hairs, leaves mostly basal; cypselae rugose, glabrous Hypochaeris L. (금혼초속)
2. Plant hispid with anchor hairs, Leaves basal and cauline, basal leaves withered at flowering; cypselae transversely ridged, scales ·························· Picris L. (쇠서나물속)
1. Heads peduncle inflated and ridged at fruiting; involucres biseriate, inner phyllaries hardened and convex at fruiting, enveloping outer cypselae; cypselae slightly and longitudinally ridged; pappus scales or scale-like bristles ···· ·································· Hedypnois Mill. (금혼초아재비속)
Acknowledgements
This study was supported by the project “Research on taxonomy and distribution of invasive alien plants in Korea (KNA1-2-39, 21-2),” which is funded by the Korea National Arboretum.
Notes
CONFLICTS OF INTEREST
The authors declare that there are no conflicts of interest.