Korea. Gangwon Province: Jeongseon-gun, Sindong-eup, Unchi-ri, Donggang River, rocky cliffs along the riverside, 37°16'25.7"N, 128°36'33.8"E, alt. 264 m, 8 September 2021, J.H.Song & S. Yang, KIOM-2021-802-1 [Holotype: KIOM! (Fig. 6B); Isotype KB!].

Peucedanumtongkangense is similar to P.miroense, but differs in its subglabrous (vs. pubescent) ovary, yellowish white (vs. purple) anthers, narrowly ellipsoid (vs. oblong) schizocarp, 13–16 vittae (3 per vallecula, 4 on commissure) [vs. 8 or 9 vittae, 1 or (2) per vallecula, 4 on commissure] per mericarp. Peucedanumtongkangense is also similar to P.elegans and P.hakuunense but is distinct from both in the acute (vs. spine-tipped) apex of the ultimate leaf segments and 2-pinnate (vs. 1- or 2-ternate) leaves (Table 1).

Herb, perennial, hermaphroditic, (60–)75–95(–120) cm tall. Root a taproot, whitish or pale yellow, elongated, thickened, 17–23 × 0.4–1.5 cm. Rhizomes erect or ascending, yellowish white, cylindrical, approximately 0.6–1.1 cm in diameter, woody. Stems erect, purplish green, much branched, 3–9 mm in diameter, terete, longitudinally grooved, solid, glabrous, with fibrous remnants of basal leaves. Leaves basal and cauline, alternate, pinnately compound, petiolate; petiole sheathing at base; stipules absent. Basal leaves many, 3-pinnate, usually deciduous; petiole 8.5–10.5 cm long, glabrous; sheath purplish or yellowish green, cylindrical, not inflated, 1.3–2 cm × 3.6–8.5 mm, margins scarious, glabrous; blade elliptic to rhombic in outline, 15–21.5 × 12–16.8 cm, both surfaces green, glabrous; petiolule of terminal leaflet 2.7–4.8 cm long; terminal leaflet triangular or ovate-rhombic, 2-pinnatisect, 3.5–5 × 2.8–4.1 cm, apex acute, base cuneate, margins entire; petiolule of basal lateral leaflets 1.8–3.8 cm long; lateral leaflets elliptic to elliptic-ovate, 3-pinnatisect, 7.1–9.9 × 4.7–5.4 cm, apex acute, base cuneate, margins entire, uppermost leaflets sessile; ultimate segments narrowly oblong-lanceolate to linear, 1.3–2 cm × 2.8–4.3 mm. Cauline leaves similar to basal ones and becoming smaller upward; petiole of lower cauline leaves (2–)2.8–4.5 cm long, reduced upward, glabrous; blade elliptic to ovate in outline; uppermost cauline leaves ovate to rhombic, 1- or 2-pinnatisect, 0.9–2.4 × 1.1–2.7 cm, sessile. Inflorescences terminal and lateral, with 15–48 compound umbels, more or less flat-topped, 3.5–8.8 cm in diameter; umbellets hermaphroditic, 15- to 25-flowered, 0.5–1.2 cm in diameter; peduncle 2.5–5 cm long, glabrous; rays 16–18, spreading to ascending, 1–2.5 cm long, unequal in length, adaxial surface sparsely pubescent with short simple unicellular hairs; bract 1, persistent or sometimes caducous, lanceolate, entire, 0.7–2 cm × 1–1.5 mm, apex acute, margins scarious, glabrous; pedicels 1.5–2.5(–5) mm long, adaxial surface sparsely pubescent with simple unicellular hairs; bractlets 5–6, persistent, linear, entire, 2.5–7 × 0.4–0.8 mm, apex acute, glabrous. Flowers bisexual, actinomorphic, 2.4–3.2 mm in diameter; calyx 5-toothed; calyx teeth minute, narrowly triangular, 0.2–0.4 × 0.1–0.2 mm, adaxial surface glabrous, abaxial surface sparsely pubescent with short conical simple unicellular hairs or glabrous; petals 5, white, obcordate, 0.7–1.3 × 0.9–1.6 mm, apex incurved, base cuneate to caudate, glabrous; stamens 5, alternating with petals; filaments filiform, 1.6–2.5 mm long; anthers 2-locular, yellowish white, introrse, versatile, dehiscing longitudinally, subglobose, 0.5–1.1 × 0.8–1.2 mm; pistil 1, 2-carpellate; ovary inferior, syncarpous, 2-locular, subglabrous; stylopodium conical; styles 2, free, ascending, 0.3–0.7 mm at anthesis, 1.0–1.7 mm in fruit, swollen at base to form a stylopodium, reflexed in fruit; ovule 1 per locule, anatropous, pendulous. Fruit a dry schizocarp composed of 2 mericarps, pale brown to brown at maturity, narrowly ellipsoid; carpophore 2.1–2.4 mm long, 2-cleft; mericarps splitting apart at maturity, narrowly ellipsoid, slightly dorsally compressed, 3.8–4.4 × 1.5–2 mm, subglabrous to sparsely tuberculate on dorsal side, glabrous on commissural side; dorsal ribs 3, filiform, not winged; marginal ribs 2, slightly winged; wings 0.2–0.3 mm wide, scarious; secondary ribs absent; vittae 13–16, 3 per vallecula and 4 on commissure; commissure 0.9–1.2 mm wide. Seed 1 per mericarp; oblong in cross-section; face plane.

Flowering September to October. Fruiting October to November.

The specific epithet ‘tongkangense’ refers to the rocky cliffs along the Donggang River, where the type specimen was collected.

Dong-gang-gi-reum-na-mul

Peucedanumtongkangense grows in open areas on rocky cliffs near the Donggang River in Gangwon Province and the Namhangang River in North Chungcheong Province, South Korea. Five populations were found: the type locality and those at Unchi-ri, Sindong-eup, Jeongseon-gun, Gangwon Province, along the Dong-gang river at 150–400 m elevations (Fig. 5). The type locality was growing with ArtemisiasacrorumLedeb.var.iwayomogi (Kitam.) M.S. Park & G.Y. Chung, Asterscaber Thunb., Galinsogaciliata (Raf.) S.F. Blake (Asteraceae), Boehmeriaspicata (Thunb.) Thunb. (Urticaceae), Calamagrostispurpurea (Trin.) Trin. (Poaceae), Carexsiderosticta Hance (Cyperaceae), Humulusscandens (Lour.) Merr. (Cannabaceae), Isodoninflexus (Thunb.) Kudô (Lamiaceae), Parthenocissustricuspidata (Siebold & Zucc.) Planch. (Vitaceae), Polystichumcraspedosorum (Maxim.) Diels (Dryopteridaceae), Rubiaargyi (H. Lév. & Vaniot) H. Hara ex Lauener & D.K. Ferguson (Rubiaceae), Scabiosacomosa Fisch. ex Roem. & Schult. (Caprifoliaceae), and Spiraeablumei G. Don (Rosaceae). Three populations of P.tongkangense were also found along the Donggang River where they were growing with Asteryomena (Kitam.) Honda (Asteraceae), Clematisserratifolia Rehder (Ranunculaceae), and Trichophorumdioicum J. Jung & H.K. Choi (Cyperaceae). The fifth population was near the Namhangang River in North Chungcheong Province where it was growing with Gypsophilaoldhamiana Miq. (Caryophyllaceae), Mukdeniarossii (Oliv.) Koidz. (Saxifragaceae), Patriniarupestris (Pall.) Dufr. (Caprifoliaceae), Potentilladickinsii Franch. & Sav. (Rosaceae), Pyrrosiapetiolosa (Christ) Ching (Polypodiaceae), and Selaginellastauntoniana Spring (Selaginellaceae).

Korea. Gangwon Province: Yeongwol-gun, Seo-myeon, Ongjeong-ri, 37°13'5.3"N, 128°20'56.6"E, alt. 234 m, 13 October 2010, B.-Y. Lee et al., SHY2322 (KB); Gangwon Province: Jeongseon-gun, Hwaam-myeon, Bukdong-ri, 37°22'4.78"N, 128°47'54.35"E, alt. 687 m, 25 September 2012, G.-H. Nam & J.-H. Kim, SHY3-2023 (KB); Jeongseon-eup, Yeotan-ri, 37°22'05.6"N, 128°43'41.9"E, alt. 30 October 2016, K. Kim & H.-J. Suh, KK3510 (SNU); Gangwon Province: Jeongseon-gun, Nam-myeon, Nakdong-ri, 37°18' 38.47" N, 128°42'43.27"E, alt. 719 m, 01 September 2016, J.-H. Kim & H.-J. Park, Beaki161681 (KB).

After conducting field surveys throughout the country and examining specimens from several domestic herbaria, three more populations along the Donggang River, Gangwon Province were documented for Peucedanumtongkangense. According to the IUCN criteria, P.tongkangense is classified as least concern (IUCN 2022; LC), because it is distributed widely and a considerable number of individuals is known.

Peucedanumtongkangense is morphologically similar to P.miroense but it is clearly distinct due to its subglabrous ovary, yellowish white anthers, narrowly ellipsoid schizocarp, and 13–16 vittae (3 per vallecula and 4 on commissure) in mericarp; P.miroense has a pubescent ovary, purple anthers, oblong schizorcarp, and 8–10 vittae [1 or (2) per vallecula and 4 on commissure]. Additionally, P.tongkangense is similar to P.elegans and P.hakuunense but is distinguished from P.elegans by the acute apex of the ultimate leaf segments (vs. spine-tipped) and from P.hakuunense by its 2-pinnate leaves (vs. 1- or 2-ternate leaves) (Table 1).

North Chungcheong Province is also a major limestone area in Gangwon Province. Thus, it is necessary to add P.tongkangense to the limestone flora list for Korea (Kim et al. 2021).