In Korea, two alien plants were newly found, and we describe their morphological characteristics and habitats with photographs. One, a member of Cyperaceae, Carex annectens, was found in roadside forests from Gyeongsangnam-do. This species can be distinguished from C. gravida by having inflorescences, usually branched, with more than 15 spikes and pistillate scale yellow or brown. The other is C. gravida, which was found along roadsides of open habitats from Chungcheongnam-do and Gyeonggi-do. This species can be distinguished from C. muehlenbergii Schkuhr ex Willd. var. enervis Boott by having proximal leaf sheaths longitudinally green-and-white striped and with prominent green cross veins. These species grow on roadsides, suggesting that they were likely to have been introduced when green sites were installed and during road construction. Their introduction into Japan has been reported, but the associated ecological risk is unknown. Therefore, we need continuous population monitoring for these new invasive species in Korea.

Keywords: alien plants; Carex annectens; Carex gravida; Cyperaceae; subgenus Vignea

INTRODUCTION

The genus Carex L. (Cyperaceae) is one of the largest genera of vascular plants, comprising nearly 2,000 species distributed almost worldwide in various habitats (Ohwi, 1936; Ball and Reznicek, 2002; Dai et al., 2010; Global Carex Group, 2021; WCSP, 2024). In Korea, there are 157 Carex species (Oh, 2006, 2007, 2018). More recently, the Checklist of Korean Plants (Korea National Arboretum, 2020, 2021) listed 199 species, including alien plants. Later, an additional species was reported (Kim et al., 2022).

Carex has been placed within the tribe Cariceae and divided into several subgenera in many ways based on the following characters: the stigma number, achene shape, inflorescence structure, and arrangement of the staminate and pistillate flowers within the spikes (Ball, 1990; Reznicek, 1990; Goetghebeur, 1998; Nam et al., 2020). Traditional subgeneric classification was recognized by Kükenthal (1909): subg. Carex, subg. Psyllophorae (Degl.) Peterm., subg. Vignea (P. Beauv. ex T. Lestib.) Peterm., and subg. Vigneastra (Tuck.) Kük. Recently, molecular data have suggested the infrageneric classification of Carex, classifying it into the following six subgenera: subg. Carex, subg. Euthyceras Peterm., subg. Psyllophorae, subg. Siderosticta M. J. Waterway, subg. Uncinia (Pers.) Peterm., and subg. Vignea (P. Beauv. ex T. Lestib.) Heer (Villaverde et al. 2020; Global Carex Group, 2021).

Carex subg. Vignea is perhaps the best morphologically defined large group in the genus (Jiménez-Mejías et al., 2021). It includes approximately 320 species in 25 sections distributed mainly in extra-tropical and, very rarely, in tropical areas of the Northern Hemisphere, with a few species also occurring in the Southern Hemisphere (Egorova, 1999; Ball and Reznicek, 2002; Dai et al., 2010). Subg. Vignea is characterized by sessile and bisexual spikes, distigmatic flowers, and a lack of cladoprophylls (Ford et al., 2006). One of the most remarkable diagnostic characteristics of the taxonomy of subg. Vignea is the arrangement of mono-sexual spikelets within the spikes, which remains more or less consistent in most groups (Jiménez-Mejías et al., 2021). Taxonomic identification keys soon delineate species with androgynous spikes and those with gynaecandrous spikes (Egorova, 1999; Ball and Reznicek, 2002; Dai et al., 2010). In Korea, subg. Vignea is composed of 22 species in eleven sections (Ohwi, 1936; Oh and Jo, 2003; Oh, 2006). However, some of the species in certain sections have been transferred to (or the entire section merged with) other groups (Dai et al., 2010; Hoshino et al., 2020; Global Carex Group, 2021). Over the past few years, unrecorded alien sedge species from Korea have been reported occasionally (Cheon et al., 2014; Ko et al., 2020; Korea National Arboretum, 2021, 2024). Therefore, there are currently 27 species in 12 sections distributed in Korea.

During a plant diversity field survey, C. annectens (E. P. Bicknell), E. P. Bicknell, and C. gravida L. H. Bailey, previously unrecorded as Korean flora, were collected in Korea. Carex annectens belongs to the section Multiflorae (J. Carey) Kük., which consists of seven species, mainly from North America and Mexico and introduced into Europe, New Zealand, and Japan (Standley, 2002; Hoshino et al., 2011, 2020). Carex gravida belongs to the sect. Phaestoglochin Dumort. The sect. Phaestoglochin includes ca. 27 species that are mainly in the temperate regions of the Northern Hemisphere, with some species introduced into Japan (Ball, 2002; Hoshino et al., 2020). Two species of the subgenus Vignea belonging to the genus Carex (Ball, 2002; Standley, 2002; Mohlenbrock, 2011; Hoshino et al., 2020) are discovered in Korea for the first time.

We here formally report the first occurrence of the Carex annectens and C. gravida in Korea (Figs. 1 –3). We provide morphological characteristics with photographs and a taxonomic key to related taxa as well as habitat details for both.

Fig. 1.

Distributions of Carex annectens (E. P. Bicknell) E. P. Bicknell (●) and C. gravida L. H. Bailey (■) in Korea.

Fig. 2.

Photographs of Carex annectens (E. P. Bicknell) E. P. Bicknell. A. Habit. B. Inflorescence (a, flowering season; b, fruiting season). C. Leaf sheath (a, adaxial view; b, abaxial view). D. Perigynia. E. Achenes.

Fig. 3.

Photographs of Carex gravida L. H. Bailey. A. Habit. B. Inflorescence (a, flowering season; b, fruiting season). C. Leaf sheath (a, adaxial view; b, abaxial view; red arrow indicates: green cross veins). D. Perigynia. E. Achenes.

TAXONOMIC TREATMENT

Carex annectens (E. P. Bicknell) E. P. Bicknell, Bull. Torrey Bot. Club 35: 492, 1908; Carex xanthocarpa var. annectens E. P. Bicknell, Bull. Torrey Bot. Club 23: 22, 1896.—TYPE: U.S.A. Richmond Valley, 6 Jul 1895, N. L. Britton s.n. (holotype: NY, 00688245, photo!).

Korean name: Na-do-mi-guk-ta-rae-sa-cho (나도미국타래사초).

Plants perennial, densely cespitose. Rhizome short, fibrous roots. Culms trigonous, 30–80 cm tall, smooth; basal sheaths tight, fronts indistinctly spotted pale brown or red, membranous, rugose. Leaves basal and cauline; blades Vshaped in the cross-section, filiform, shorter than culms, 2–5 mm wide, apex acuminate, glabrous, smooth. Inflorescences spicate, 4–7 cm × 3–10 mm, with 10–15 branches, proximal usually distinct; proximal internodes shorter than 1.5 cm; terminal spike androgynous; lateral spikes usually pistillate or sometimes androgynous, sessile, without cladoprophylls. Bracts setaceous; lowest bract shorter than inflorescences, filiform, up to 5 cm long, sheathless. Pistillate scales yellowbrown or red-brown, equaling or longer than perigynia, lanceolate, 3–3.5 × 1–2 mm, apex acuminate to long-awned, midrib usually green. Stamens 3; anthers linear, 1–1.2 mm long. Perigynia yellow-brown to greenish, loosely spreading, broadly elliptic to ovate, shorter than pistillate scales, 2–3 mm long, apex abruptly contracted into a short beak, base slightly spongy, margins serrulate distally, glabrous, inconspicuously 3-veined, orifice emarginate or bidentate. Achenes rather loosely enveloped, biconvex, circular, 1–1.5 mm wide; style deciduous, short, base flattened; stigma 2.

Flowering: May to June.

Fruiting: June to July.

Distribution and habitat: Carex annectens is native to eastern North America, whereas this species is non-native in Japan (Standley, 2002; Hoshino et al., 2011, 2020; Mohlenbrock, 2011). In this study, we report the alien plant C. annectens for the first time in Korea. It was initially detected in Gyeongsangnam-do in 2022 and confirmed again during the flowering and fruiting seasons of 2023 and 2024. This species is distributed along the roadsides of forests at elevations of 430–450 m a.s.l. The population was composed of 20 individuals within an area of 5 × 5 m². The shrub vegetation includes Boehmeria spicata (Thunb.) Thunb., Rosa multiflora Thunb., Rubus crataegifolius Bunge, Lespedeza maximowiczii C. K. Schneid., Pueraria lobata (Willd.) Ohwi, and Zanthoxylum piperitum (L.) DC.; the herbaceous vegetation is made up of Plantago asiatica L., Artemisia indica Willd., Erigeron annuus (L.) Pers., Taraxacum officinale F. H. Wigg., Carex japonica Thunb., Dactylis glomerata L., Eragrostis curvula (Schrad.) Nees, Festuca arundinacea Schreb., Phalaris arundinacea L., and Dioscorea quinquelobata Thunb.

Specimens examined: KOREA. Gyeongsangnam-do: Goseong-gun, Sangri-myeon, Dongsan-ri, 22 Jun 2022, Jung-Hyun Kim KIMJH22102 (2 sheets, KB), KIMJH22103 (2 sheets, KB), KIMJH22104 (2 sheets, KB); 7 Jun 2023, Jung-Hyun Kim KIMJH23349 (KB), KIMJH23350 (KB); 20 May 2024, Jung-Hyun Kim KIMJH24204 (KB), KIMJH24205 (2 sheets, KB), KJH24199 (2 sheets, NNH), KJH24200 (3 sheets, NNH).

Carex gravida L. H. Bailey, Mem. Torrey Bot. Club 1: 5, 1889.—TYPE: U.S.A. Ringwood, Illinois, without date, G. Vasey 75 (holotype: NY, 00011124, photo!).

Korean name: Jul-mu-nui-mi-guk-ta-rae-sa-cho (줄무늬미국타래사초).

Plants perennial, densely cespitose. Rhizomes short. Culms trigonous, 30−100 cm tall, smooth; basal sheaths usually loose, proximally green-and-white striped, not white spotted, with conspicuous transverse veins on back, fronts hyaline, sometimes transversely rugose and red dotted, thin, white or hyaline and fragile at mouth. Leaves basal and cauline; blades V-shaped in the cross-section, filiform, equaling or much shorter than culms, 4–8 mm wide, apex acuminate, glabrous, smooth. Inflorescences spicate, 2–5 cm × 8–15 mm, with 5–15 spikes; proximal internodes shorter than to 1.5 times as long as proximal spikes; terminal spike androgynous; lateral spikes usually pistillate or sometimes androgynous, sessile, without cladoprophylls. Bracts leaf-like or setaceous; lowest bract shorter than inflorescences, filiform, up to 3 cm long, sheathless. Pistillate scales hyaline or greenish or light brown, equaling or shorter than perigynia, ovate, 2.5–4.5 × 1.3–2.4 mm, apex acuminate to short-awned, midrib usually green or pale brown. Stamens 3; anthers linear, 2–3 mm long. Perigynia pale green to yellowish brown, ascending or spreading, ovate to oblong-ovate or obovate, shorter than pistillate scales, 4–5.5 mm long (including beak), apex abruptly contracted into a short beak, base thickened and spongy, margins serrulate distally, glabrous, inconspicuously 2–7-veined or veinless, orifice emarginate or shallowly bidentate. Achenes rather loosely enveloped, biconvex, circular to elliptic-circular, 2–2.5 mm wide; style deciduous, short, base thickened; stigma 2.

Flowering: May to June.

Fruiting: June to July.

Distribution and habitat: Carex gravida is native to central and eastern North America, whereas this species is non-native in Japan (Ball, 2002; Mohlenbrock, 2011; Hoshino et al., 2020). In this study, we report the alien plant C. gravida for the first time in Korea. It was initially detected in Gyeonggi-do in 2021 and confirmed again during the flowering and fruiting seasons of 2023 and 2024, after which it was also found in Chungcheongnam-do. This species is distributed along roadsides of open habitats at an elevation of 70–160 m a.s.l. One population (Gyeonggi-do) was composed of 30 individuals within an area of 20 × 5 m², and the other (Chungcheongnam-do) was composed of ten individuals within an area of 5 × 3 m². The canopy vegetation includes Clematis apiifolia DC., Quercus acutissima Carruth., Pueraria lobata (Willd.) Ohwi, Morus alba L., and Paederia foetida L.; the herbaceous vegetation is made up of Chelidonium majus L. var. asiaticum (H. Hara) Ohwi, Chenopodium album L., Achyranthes bidentata Blume var. japonica Miq., Stellaria media (L.) Vill., Capsella bursapastoris (L.) Medik., Rorippa indica (L.) Hiern, Oxalis corniculata L., Chaerophyllum tainturieri Hook. & Arn., Metaplexis japonica (Thunb.) Makino, Trigonotis peduncularis (Trevir.) Steven ex Palib., Leonurus japonicus Houtt., Galium spurium L., Ageratina altissima (L.) R. M. King & H. Rob., Ambrosia trifida L., Artemisia indica Willd., Erigeron annuus (L.) Pers., Taraxacum officinale F. H. Wigg., Youngia japonica (L.) DC. subsp. elstonii (Hochr.) Babc. & Stebbins, Commelina communis L., Carex gibba Wahlenb., C. japonica Thunb., Dactylis glomerata L., and Oplismenus undulatifolius (Ard.) Roem. & Schult.

Specimens examined: KOREA. Chungcheongnam-do: Seosan-si, Palbong-myeon, Geumhak-ri, 30 May 2024, Jung-Hyun Kim KIMJH24208 (2 sheets, KB), KIMJH24209 (2 sheets, KB), KJH24203 (3 sheets, NNH); 18 Jun 2024, Jung-Hyun Kim KIMJH24210 (2 sheets, KB), KJH24204 (2 sheets, NNH). Gyeonggi-do: Seoul-si, Mapo-gu, Sangam-dong, 31 May 2021, Jin-Seok Kim KPDI-N20230865 (NNH); 23 May 2023, Jin-Seok Kim KPDI-N20230866 (4 sheets, NNH); 22 May 2024, Jung-Hyun Kim KIMJH24206 (KB), KIMJH24207 (2 sheets, KB), KJH24201 (3 sheets, NNH), KJH24202 (2 sheets, NNH).

Key to the sections of Carex subgenus Vignea and related taxa in Korea

1. Terminal spike gynecandrous; lateral spikes gynecandrous or pistillate ····································· C. sect. Ovales 타래사초절
1. Terminal spike androgynous; lateral spikes androgynous, staminate, or pistillate.
- 2. Perigynia mostly more than 2 times as long as wide, widest near base ··························· C. sect. Vulpinae 양덕사초절
- 2. Perigynia mostly not more than 2 times as long as wide, widest near middle.
  - 3. Inflorescences usually branched, at least proximally, usually with more than 15 spikes; pistillate scale yellow or brown ······························································ C. sect. Multiflorae 나도미국타래사초절, C. annectens 나도미국타래사초
  - 3. Inflorescences unbranched or with 1–2 short branches proximally, with not more than 15 spikes; pistillate scale greenish hyaline ·············································································································· C. sect. Phaestoglochin 미국타래사초절
    
    4. Proximal leaf sheaths longitudinally green-and-white-striped and with prominent green cross veins, usually loose; widest leave blade 4–8 mm wide ·········································································· C. gravida 줄무늬미국타래사초
    
    4. Proximal leaf sheaths unstriped or indistinctly striped, without prominent cross veins, tight; widest leave blade 2−4 mm wide ··························································································· C. muehlenbergii var. enervis 미국타래사초

Acknowledgements

We thank Dr. Paul Ernest Rothrock at Indiana University Bloomington for his help with verification of the taxonomic identification. We also thank Mr. Hyeon Rae Jo, Ik Hee Kim, Inbae Lee, and Dongchan Hong for their help in providing information on the natural habitat and collecting specimens. This work was supported by a grant from the Nakdonggang National Institute of Biological Resources (NNIBR) funded by the Ministry of Environment (MOE) of the Republic of Korea (NNIBR202301102, NNIBR20241102).

Notes

CONFLICTS OF INTEREST

The authors declare that there are no conflicts of interest.

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