Peucedanum tongkangense K. Kim, H.J.Suh & J.H.Song, 2022

Kim, Kyeonghee, Suh, Hwa-Jung & Song, Jun-Ho, 2022, Two new endemic species, Peucedanum miroense and P. tongkangense (Apiaceae), from Korea, PhytoKeys 210, pp. 35-52 : 35

Peucedanum tongkangense K. Kim, H.J.Suh & J.H.Song sp. nov.

Figs 3 , 4 , 6B

Type.

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!] .

Diagnosis.

Peucedanum tongkangense 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. Peucedanum tongkangense 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 ).

Description.

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.

Phenology.

Flowering September to October. Fruiting October to November.

Etymology.

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

Vernacular name.

Dong-gang-gi-reum-na-mul

Distribution and ecology.

Peucedanum tongkangense 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 Artemisia sacrorum Ledeb. var. iwayomogi (Kitam.) M.S. Park & G.Y. Chung, Aster scaber Thunb., Galinsoga ciliata (Raf.) S.F. Blake ( Asteraceae ), Boehmeria spicata (Thunb.) Thunb. ( Urticaceae ), Calamagrostis purpurea (Trin.) Trin. ( Poaceae ), Carex siderosticta Hance ( Cyperaceae ), Humulus scandens (Lour.) Merr. ( Cannabaceae ), Isodon inflexus (Thunb.) Kudô ( Lamiaceae ), Parthenocissus tricuspidata (Siebold & Zucc.) Planch. ( Vitaceae ), Polystichum craspedosorum (Maxim.) Diels ( Dryopteridaceae ), Rubia argyi (H. Lév. & Vaniot) H. Hara ex Lauener & D.K. Ferguson ( Rubiaceae ), Scabiosa comosa Fisch. ex Roem. & Schult. ( Caprifoliaceae ), and Spiraea blumei G. Don ( Rosaceae ). Three populations of P. tongkangense were also found along the Donggang River where they were growing with Aster yomena (Kitam.) Honda ( Asteraceae ), Clematis serratifolia Rehder ( Ranunculaceae ), and Trichophorum dioicum J. Jung & H.K. Choi ( Cyperaceae ). The fifth population was near the Namhangang River in North Chungcheong Province where it was growing with Gypsophila oldhamiana Miq. ( Caryophyllaceae ), Mukdenia rossii (Oliv.) Koidz. ( Saxifragaceae ), Patrinia rupestris (Pall.) Dufr. ( Caprifoliaceae ), Potentilla dickinsii Franch. & Sav. ( Rosaceae ), Pyrrosia petiolosa (Christ) Ching ( Polypodiaceae ), and Selaginella stauntoniana Spring ( Selaginellaceae ).

Additional specimens examined (Paratypes).

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, Beaki 161681 (KB) .

Proposed IUCN conservation status.

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 Peucedanum tongkangense . 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.

Taxonomic notes.

Peucedanum tongkangense 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).

Comparative mericarp micromorphology

Micromorphological characteristics of fruits using scanning electron microscopy (SEM) have provided valuable information in classifying and identifying taxa of Apiaceae ( Ostroumova 2018 and references therein). Significantly, SEM micrographs helped to visualize trichome types and small rounded projections, such as tubercules ( Ostroumova 2018; Lee et al. 2018).

In our study, we found that P. miroense and P. elegans have short, simple unicellular hairs with a striate surface. Hair length in P. miroense was up to 40 μm long, and up to 10 μm long in P. elegans (Fig. 7 ). Peucedanum tongkangense and P. hakuunense had tubercules 20-30 μm in diameter (Fig. 7 ). The micromorphological measurements of the mericarps of P. miroense and P. tongkangense differ from other species. Peucedanum has at least two types of mericarp surface.

Key to the species of Peucedanum in Korea

1	Basal and cauline leaves 1- to 3-pinnately compound	2
2	Ultimate segments of leaves linear	3
3	Umbellets 20- to 44-flowered. Vittae 6, 1 per vallecula and 2 on commissural face	4
4	Leaves 2-pinnately compound; blade triangular to broadly ovate in outline; ultimate segments linear-lanceolate, apex acute, not spine-tipped. Bracts 1 or 2	1. P. paishanense
4'	Leaves 2- or 3-pinnately compound; blade ovate in outline; ultimate segments linear, apex spine-tipped. Bracts 5-7	2. P. elegans
3'	Umbellets 16- to 20-(to 27)-flowered. Vittae 8-18, 1-3 per vallecula, 4 or 6 on commissural face	5
5	Plants 10-20 cm tall. Bracts 2-7; bractlets 10-12	3. P. coreanum
5'	Plants 50-80 cm tall. Bract 1 or absent; bractlets 6-10	6
6	Anthers purple. Mericarp pubescent with short simple hairs. Schizocarp oblong; vittae 8 or 9, 1 or (2) per vallecula, 4 on commissural face	4. P. miroense
6'	Anthers yellowish white. Mericarp subglabrous to sparsely tuberculate. Schizocarp narrowly ellipsoid; vittae 13-16, 3 per vallecula, 4 on commissural face	5. P. tongkangense
2'	Ultimate segments of leaves lanceolate to elliptic, not linear	7
7	Apex of ultimate leaf segments acute; vittae 6, 1 per vallecula and 2 on commissure	6. P. terebinthaceum
7'	Apex of ultimate leaf segments rounded; vittae 20-38; 3 or 4 per vallecula and 8-12 on commissure	8
8	Leaf blades ovate to triangular in outline, both surfaces glabrous. Bracts 1-4, lanceolate; bractlets 4-8, lanceolate to narrowly triangular	7. P. chujaense
8'	Leaf blades triangular or broadly triangular in outline, both surfaces sparsely pubescent with short simple hairs along veins. Bracts 1, 2 or absent, lanceolate or narrowly triangular; bractlets 8-10, lanceolate to linear	8. P. litorale
1'	Basal and cauline leaves 1- or 2-ternately compound	9
9	Leaves coriaceous, both surfaces glaucous; ultimate leaf segments obovate or elliptic. Calyx teeth obsolete. Seed face slightly concave in cross-section	9. P. japonicum
9'	Leaves not coriaceous, adaxial surface green, abaxial surface pale green; ultimate leaf segments linear. Calyx teeth prominent, triangular. Seed face plane in cross-section	10. P. hakuunense

Figures

Figure 3. Photographs of Peucedanum tongkangense K. Kim, H. J. Suh & J. H. Song A-C habitat D basal leaves E cauline leaf F compound umbel (early flowering stage) G-H compound umbel (mature flowering stage) I compound umbel (fruiting stage) J bractlets K rays L flowers M calyx teeth and stylopodium (mature fruiting stage) N dorsal side of mericarp O commissural side of mericarp P transverse plane of mericarp. cv, commissure vittae; dr, dorsal ribs; dv, vallecula vittae; mr, marginal ribs; tr, trichomes; vb, vascular bundles.

Figure 4. Peucedanum tongkangense K. Kim, H. J. Suh & J. H. Song A habit B flower C umbellet D basal cauline leaf E mericarp (dorsal side) F mericarp (commissural side) G mericarp (cross-section) (A-F J. H. Song & S. Yang, KIOM 2021 - 729 - 1).

Figure 5. Distribution of Peucedanum miroense and P. tongkangense = gray ellipse. P. miroense = black circle. P. tongkangense = black squares. Blue lines: rivers.

Figure 6. Holotype of A Peucedanum miroense K. Kim, H. J. Suh & J. H. Song (J. H. Song & S. Yang, KIOM- 2021 - 646 - 1) and B P. tongkangense K. Kim, H. J. Suh & J. H. Song (J. H. Song & S. Yang, KIOM- 2021 - 802 - 1).

Figure 7. Scanning electron micrographs of mericarp surface of four species of Peucedanum A P. miroense B P. tongkangense C P. hakuunense D P. elegans. All scale bars: 10 μm.