1. INTRODUCTION

Ipomoea L. is the largest genus in Convolvulaceae, comprising approximately 800 species (Austin 1998;Wood et al. 2015, 2020). The genus is widely distributed over tropical and temperate regions worldwide, with its species diversity concentrated in the Americas, particularly in tropical and subtropical regions such as Mexico, Brazil, and Argentina (Austin 1998;Wood et al. 2020). Ipomoea is one of the genera with the highest number of naturalized alien plants globally (Pyšek et al. 2017). In Korea, alien Ipomoea species occur as naturalized and casual plants, inhabiting a variety of habitats such as disturbed sites, agricultural lands, urban areas, and semi-natural environments, with several species now widely distributed throughout the country (Kang et al. 2025). However, many taxa within the genus are morphologically similar, complicating accurate species-level identification. Therefore, a sound taxonomic understanding of Ipomoea and accumulation of baseline data for species identification are essential for accurate floristic surveys, alien plant monitoring, and establishment status assessments. A total of nine taxa of Ipomoea have been recorded in natural ecosystems in Korea: Ipomoea coccinea L., I. cristulata Hallier f., I. hederacea Jacq., I. heptaphylla Sweet, I. lacunosa L., I. nil (L.) Roth, I. pes-caprae (L.) R.Br., I. purpurea (L.) Roth, and I. triloba L. (Kang et al. 2023, 2025;Youn et al. 2023;KPNI 2026;Son et al. 2026).

Among the infrageneric groups of Ipomoea, Ipomoea ser. Batatas (the sweet potato group) is economically important, as sweet potato [Ipomoea batatas (L.) Lam.] and its wild relatives are valuable genetic resources contributing to global food security (Huang et al. 2002;Rathnayake et al. 2020;Syamsurizal et al. 2021;Simões et al. 2024). Ipomoea members of this group are generally characterized by chartaceous sepals with a well-developed mucro, white to pink corollas, and ovaries and capsules that are often pubescent (Austin 1978;Wood et al. 2020). The group is taxonomically complicated because of overlapping morphological variation, extensive synonymy, and frequent hybridization, all of which obscure species boundaries (Wood et al. 2020). Therefore, species identification within this group requires careful comparison of diagnostic characters such as root morphology, corolla size and color, sepal shape and texture, nectary disc color, capsule indumentum, and seed morphology.

In Korea, cultivated sweet potato (I. batatas) is widely grown, and two alien species of Ipomoea ser. Batatas, I. lacunosa L. and I. triloba L., have previously been recorded as wild-growing taxa (Park 2009;Kim and Kil 2017;Kang et al. 2025;KPNI 2026). We found an unidentified Ipomoea taxon in disturbed habitats in Jeju-si on Jejudo Island (Fig. 1). Morphological comparison indicated that the plants were distinct from the Korean members of Ipomoea ser. Batatas. Based on detailed morphological examination and comparison with relevant taxonomic literature and herbarium specimens, the Korean plants were identified as Ipomoea trifida (Kunth) G.Don. Based on phylogenomic evidence, this species has recently been suggested to be the putative progenitor of the cultivated sweet potato, I. batatas (Muñoz-Rodríguez et al. 2018).

Here, we report I. trifida, a newly recorded alien plant in Korea, and provide a morphological description, distributional information, taxonomic notes, voucher information, and an identification key to the Korean species of Ipomoea, including cultivated I. batatas for comparison.

2. MATERIALS AND METHODS

Field surveys were conducted in Jeju-si, Jeju-do, Korea, from 2024 to 2026. Habitat conditions, flowering and fruiting phenology, repeated occurrences, and accompanying vascular plants were recorded during field observations. Living plants were photographed in the field, and voucher specimens were collected from the Korean populations for morphological examination. The voucher specimens were deposited in the Korea National Arboretum Herbarium (KH). Herbarium acronyms follow the Index Herbariorum (NYBG 2026).

The morphological description was prepared based on living plants observed in the field and voucher specimens deposited in KH. The Korean material was identified through comparison with relevant taxonomic treatments of Ipomoea, especially Ipomoea ser. Batatas and the I. batatas complex (Austin 1978, 1998;Austin and Huáman 1996;Wood et al. 2015, 2020;Simões et al. 2024). Digital images of comparative specimens from A, ASU, BAYLU, BM, BRY, F, and GH were examined, as listed under “Specimens examined.” Distributional information was compiled from Wood et al. (2020), POWO (2026), and the Korean field records obtained in this study. The identification key to the Korean species of Ipomoea, including cultivated I. batatas for comparison, was prepared based on previous Korean records and the diagnostic characters confirmed in this study (Park 2009;Kim and Kil 2017;Kang et al. 2023, 2025;Kim et al. 2025b;KPNI 2026;Son et al. 2026).

3. TAXONOMIC TREATMENT

Ipomoea trifida (Kunth) G.Don, Gen. Hist. 4(1): 280, 1837 (Figs. 2, 3)

≡ Convolvulus trifidus Kunth, Nov. Gen. Sp. 3: 107, 1819.

TYPE: VENEZUELA. Amazonas, s.d., Humboldt & Bonpland 1136 (holotype P [digital image!], P00670762).

Korean name. Gae-go-gu-ma (개고구마, a new Korean name).

Twining perennial herbs. Roots thin, fibrous, not developing tuberous storage roots. Stems prostrate and twining, glabrous to sparsely pubescent. Leaves alternate, petiolate; petioles 0.7-7.1 cm long; leaf blades ovate or shallowly to deeply 3(-5)-lobed, 3.0-6.4×2.4-6.0 cm; lateral lobes rounded to auriculate; apex acute to acuminate, base cordate, margin entire, pubescent on both surfaces, ciliate, abaxially paler. Inflorescences cymose, axillary, 1-many-flowered; peduncles 1.4-11.5 cm long, glabrous to sparsely pilose distally, angular; secondary peduncles 0.9-4.4 cm long, glabrous to sparsely pilose, angular, minutely verruculose; pedicels 5-7 mm long, glabrous to sparsely pilose, angular, minutely verruculose; bracteoles narrowly lanceolate to linear, 4-5 mm long, apex acute, margin entire, glabrous or sparsely ciliate, scarious, usually caducous in fruit. Flowers bisexual, actinomorphic; sepals 5, unequal; outer 2, elliptic to ovate-lanceolate, 8-9 mm long, apex mucronate, margins ciliate, glabrous to sparsely pilose; inner 3, similar to the outer sepals, 9-10 mm long; corollas funnelform, 2.1-3.0 cm long, pale pink, darker toward the throat and limb margins, glabrous, midpetaline bands terminating in small teeth; limb unlobed, 1.4-3.4 cm in diameter; stamens 5, unequal, 3 longer and 2 shorter; filaments pubescent at base; pistil 1; style filiform, glabrous; stigma capitate; ovary 2-locular, hirsute; nectary disc yellow. Capsules subglobose, 5-7 mm in diameter, 2-celled, 4-valved, pilose. Seeds 4 or fewer, ca. 3×2 mm, trigonous, glabrous, dark brown.

Flowering and fruiting. September to December.

Distribution. Native to tropical America, from Mexico and the Caribbean to northern South America; introduced in Java and Madagascar (Wood et al. 2020;POWO 2026). Newly recorded from Korea (Jejudo Island; Fig. 1).

Specimens examined.COSTA RICA. Guanacaste: Bagaces, Comelco E., west of Bagaces, 29 Nov 1971, E.R. Heithaus 450 (BRY: BRYV0290770). CUBA. Havana: Santiago de las Vegas, 1904, H.A. van Hermann 231 (BM: BM000832243). Pinar del Río: vicinity of Los Palacios, in a field, 8 Jan 1912, J.A. Shafer 11674 (A). EL SALVADOR. La Unión: Mountains behind La Unión, sunny clearing in forest, 100 m, 12 Dec 1940, Grant V. 717 (GH). HONDURAS. Francisco Morazán: Colonia Miramonte, SE de Tegucigalpa, bosque seco subtropical, 1,000 m, 11 Nov 1999, M.G. Pineda 97 (BM: BM000832317). MEXICO. Juchitán, 10.7 km E of the Carretera Transístmica, road to Monte Obscuro, 30 Nov 2002, H. Silvia, M. Salas, A. Sánchez & A. Saynes 4780 (ASU: ASU0079328). Oaxaca: Tehuantepec, San Pedro Huamelula, Playa Grande, 0.5 km N de la playa, por el arroyo Playa Grande, 25 Nov 1998, C. M. Elorsa 1152 (ASU: ASU0080668). NICARAGUA. Matagalpa: Matagalpa, 7 Jan 1967, R.A. Molina 20101 (F). U.S.A. Texas: Falls Co., 8 Jul 1965, R. Walling 8117 (BAYLU: BAYLU036253). McLennan Co., Waco, Waco Creek, waste places, 20 Oct 1923, E.L. Hamby 1297 (BAYLU: BAYLU036284), Hamby E.L. s.n. (BAYLU: BAYLU036282). VENEZUELA. Aragua: Distrito Zamora, Hacienda El Palmar, alrededores de Tocorón, 430 m, 13 Nov 1990, T. Ruíz & R. Villafañe 4615 (F: V0442364F). KOREA. Jeju-do: Jeju-si, Hallim-eup, Geumneung-ri 1119-3, 10 Oct 2024, S.G. Lee LSG-0201 (KH: KHB1676162, KHB1676163), 17 Oct 2025, S.G. Lee LSG-0189 (KH: KHB1676161, KHB1676166), 9 Sep 2025, E.S. Kang UAP25-001 (KH: KHB1676169, KHB1676170), 11 Nov 2025, S.B. Jang UAP25-002 (KH: KHB1676164, KHB1676165). Hangyeong-myeon, Yongsu-ri 4117-3, 10 Oct 2024, S.G. Lee LSG-0199 (KH: KHB1676167, KHB1676168).

Note.Ipomoea trifida is distinguished from the cultivated I. batatas by differences in tuberous storage roots, pedicel persistence, sepal morphology, corolla size, nectary disc color, and fruit and seed production. Ipomoea trifida has only thin fibrous roots without tuberous storage roots (vs. tuberous storage roots present in I. batatas) (Fig. 3), pedicels that usually persist after fruiting (vs. caducous) (Fig. 2H), elliptic to ovate-lanceolate sepals (vs. oblong-elliptic to oblong-oblanceolate sepals) (Fig. 2D), corollas less than 4 cm long (vs. more than 4 cm long) (Fig. 2E, F), a yellow nectary disc (vs. white) (Fig. 2G), and well-developed capsules containing mature seeds (vs. capsules and seeds usually absent) (Fig. 2H, I). In addition, I. trifida is easily distinguished from the alien plants I. lacunosa and I. triloba recorded in Korea by its larger pink corollas and unequal sepals (Fig. 2D-F).

We propose the Korean name “Gae-go-gu-ma” for I. trifida. The prefix “Gae-” denotes a plant that resembles, but is distinct from, the cultivated species, and “Go-gu-ma” is the Korean common name for the cultivated sweet potato, I. batatas. Although the proposed Korean name reflects the close relationship between the two species, the presence of tuberous storage roots should not be inferred.

Key to the species of Ipomoea recorded in Korea, including cultivated I. batatas for comparison

4. DISCUSSION

Ipomoea trifida is native to the Americas, where it occurs from Mexico to Venezuela and Trinidad, as well as in Cuba, and is particularly common in Central America and Cuba (Wood et al. 2020;POWO 2026). It has also been recorded as an introduced species in Java, Madagascar, and Taiwan (POWO 2026). In Taiwan, the species was first reported in 1987 and was subsequently classified as naturalized (Ou 1987;Wu et al. 2010). This illustrates the ability of I. trifida to establish self-sustaining populations outside its native range.

The populations of I. trifida identified in Yongsu-ri and Geumneung-ri, Jejudo Island, were found around a flower bed and along a roadside adjacent to cultivated fields, respectively. These sites were frequently disturbed by cultivation, flower-bed maintenance, and roadside activities. Several plant species commonly occurring in cultivated and disturbed habitats were observed nearby, including Ipomoea coccinea L., Commelina communis L., Digitaria ciliaris (Retz.) Koeler, Pueraria lobata (Willd.) Ohwi, and Echinochloa crus-galli (L.) P.Beauv. The introduction pathway of this species into Korea remains unclear. Further investigations, including tracing the movement of agricultural and landscaping materials and soil, and interviewing local residents and land managers, would help clarify its introduction pathway. Although the exact pathway cannot currently be determined, the environmental characteristics of the sites suggest that the seeds may have been unintentionally introduced through human activities associated with flower-bed establishment, cultivation, or land development.

On Jejudo Island, I. trifida was repeatedly observed at the same localities from its initial discovery in 2024 through 2026. The presence of seedlings and flowering and fruiting individuals during this period suggests that the species can complete its life cycle and produce mature seeds under the current disturbed habitat conditions. Although no quantitative population survey was conducted, field observations suggested that approximately 30 individuals occupied an estimated area of 50 m² in Geumneung-ri. This population appeared to contain more individuals and occupy a larger area than the Yongsu-ri population, where only a few individuals were observed around a regularly maintained flower bed. No apparent spatial expansion of either population was detected during repeated field observations, although this observation was not based on a quantitative assessment. However, given the production of mature seeds and the occurrence of the species in frequently disturbed habitats, the possibility of spread into nearby suitable habitats cannot be excluded. In particular, the movement of soil and agricultural or landscaping materials may facilitate local seed dispersal (Hulme 2009;Lemke et al. 2021).

Alien plants are categorized into different invasion stages according to the barriers they have overcome and their ability to survive and reproduce. Casual alien plants may survive and reproduce occasionally in a new region but fail to establish and maintain self-sustaining populations without repeated introductions. In contrast, naturalized plants overcome barriers to survival and reproduction and maintain self-sustaining populations over multiple generations without direct human assistance (Richardson et al. 2000;Blackburn et al. 2011). Based on the observations presented above, the I. trifida populations on Jejudo Island may be at an early stage of naturalization. However, long-term monitoring of population size, occupied area, seed production, and spatial expansion is needed to clarify the establishment status and potential for spread of I. trifida in Korea.

Recently, various previously unrecorded alien plants have been continuously reported in Korea, and their discovery is likely to continue as new alien plants are introduced through human activities (Kang et al. 2023, 2024;Kim et al. 2023, 2025a;Youn et al. 2023;Jang et al. 2025). Reports of previously unrecorded alien plants, including the present record, provide baseline information for their early detection and accurate identification, thereby facilitating proactive responses to their potential establishment and spread, and strengthening alien plant management and biodiversity monitoring in Korea.