Potentilla rhizoma (Rosaceae), a new species in Korea

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Korean J. Pl. Taxon. 2024;54(4):285-289

Publication date (electronic) : 2024 December 31

doi : https://doi.org/10.11110/kjpt.2024.54.4.285

Eun-Mi SUN, JiYoung YANG¹, Seung-Chul KIM¹, Kyong-Sook CHUNG², Hyoung-Tak IM^3,

Division of Exhibition, Honam National Institute of Biological Resources, Mokpo 58762, Korea

¹Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea

²Department of Medicinal Plant Science, Jungwon University, Goesan 28204, Korea

³Department of Biology, Chonnam National University, Gwangju 61186, Korea

Corresponding author Hyoung-Tak IM E-mail: ihtplant@hanmail.net

Received 2024 November 30; Revised 2024 December 15; Accepted 2024 December 20.

Abstract

INTRODUCTION

Potentilla L. is composed of approximately 500 species, 18 of which are known in Korea. Among the Korean Potentilla species P. fragarioides is widely known as a polymorphic species (Fig. 1A) in terms of its floral characters (number of flowers, sizes of sepals and petals), number of leaflets, and density of its hairs (Naruhashi, 2003; Heo et al., 2019). Potentilla stolonifera Lehm. ex Ledeb. and P. gageodoensis M. Kim are often considered as species similar to P. fragarioides with regard to the aforementioned morphological characters (Naruhashi, 2003; Eriksen and Nylehn, 1999). During the course of morphological and ecological reexaminations of P. fragarioides, we found a new Potentilla species that grows on high mountains in the central region. The new species, Potentilla rhizoma, has morphological characters of its aerial parts similar to those of P. fragarioides but differs from P. fragarioides in having thick rhizomes that grow vigorously (Figs. 1D–G, Table 1), whereas rhizomes of P. fragarioides are short, stout and thickened tuberose types (Fig. 1B). Owing to their morphological similarity, some specimens of P. rhizoma deposited in herbaria (KB, KH, and CNU) have been identified as P. fragarioides. In addition, despite their morphological similarity, P. stolonifera Lehm. ex Ledeb. and P. fragarioides are considered to be different taxa from one another, as P. stolonifera can propagate vigorously via the stolons (Fig. 1C). Vegetative reproduction by stolons or rhizomes is an important characteristic in the life history of plant species and can also serve as a qualitative taxonomic character. Potentilla rhizoma can be considered as a unique species by having rhizomes among the Potentilla of Northeast Asia (Chaoluan, 2011; Ikeda, 2017), and should be added to the list of endemic plants on the Korean Peninsula (Chung et al., 2023).

Fig. 1.

Overall view of Potentilla fragarioides and P. stolonifera, and rhizome development of Potentilla rhizoma. A. Polymorphism of P. fragarioides (two individuals collected from the same population of Waryong-san, Sacheon-si, Gyeongsangnam-do, at a distance of two meters from each other). B. The rhizomes of P. fragarioides (marked with arrows) are short, stout, and thickly tuberous. C. P. stolonifera can propagate vigorously by means of the stolon (marked with arrows). D–G. Potentilla rhizoma. D. New rhizomes (marked with arrows) developing from the main basal part of the stem (Eundaebong, 17 Apr 2022). E. Rhizome with scaly leaves grows vigorously and new roots (marked in the circle) develop from the rhizome (17 Jun 2022). F. Aerial parts develop from each of the tips of new rhizomes (13 Sep 2022). G. Aged and lignified rhizome (13 Sep 2022).

Table 1.

Morphological characters of three Korean Potentilla (P. fragarioides, P. stolonifera and P. rhizoma).

Molecular phylogenetic studies based on the nuclear ribosomal DNA (rDNA) internal transcribed spacer (ITS) and on chloroplast DNA (two coding regions, matK and rbcL, and one noncoding intergenic region, ycf9/trnS) sequences (Im et al., unpublished data) have also provided some insights into the taxonomic distinction of the new taxon from closely related congeneric species in Korea. In the nrDNA ITS tree (not shown), P. rhizoma sampled from Eundaebong and Gariwangsan Mountain form a monophyletic group (67% bootstrap value). In addition, P. stolonifera var. quelpaertensis is the closest sister taxon to the lineage of P. rhizoma. Regarding the chloroplast DNA phylogeny (not shown), P. rhizoma is monophyletic (66% bootstrap value), and its closest sister lineage is P. rosulifera (=P. yokusaiana). The pairwise nrDNA ITS sequence divergence between P. rhizoma and closely related congeneric species is 1.04%, comparable to those of other species pairs (e.g., between P. stolonifera and P. fragarioides, 1.19%; between P. freyniana and P. squamosa, 1.15%; between P. squamosa and P. rosulifera, 1.13%). For the three cpDNA regions, the pairwise sequence divergence between P. rhizoma and closely related species is 0.13%, higher than those of other species pairs (e.g., between P. stolonifera and P. fragarioides, 0.01%; between P. freyniana and P. squamosa, 0.02%; between P. squamosa and P. rosulifera, 0.06%).

Therefore, the present molecular evidence supports the recognition of P. rhizoma as a species based on monophyly and the degree of sequence divergence.

TAXONOMIC TREATMENT

Potentilla rhizoma H.T. Im, sp. nov. TYPE: Korea. Gangwon-do, Sabuk-eup, Duwibong, 17 Apr 2021, H.T. Im 241138 (holotype: CNU) (Fig. 2).

Fig. 2.

Potentilla rhizoma H.T. Im. A. Habit. B. Rhizome. C. Pinnate leaf. D. leaflet: D-a, upper surface; D-b, lower surface. E. flower: E-a, upper surface; E-b, lower surface.

Fig. 3.

Distribution map of Potentilla rhizoma H.T. Im.

Korean name: Beod-Eum-Yang-Ji-Ggot 벋음양지꽃.

Perennial herb, 15–45 cm high. Rhizome long, thickened with scaly leaves on each node, stout, and ascending hairs. Radical leaves pinnate, 5–7(9)-foliolate, 5–10 cm long, 3–8 cm wide when flowering, up to 30 cm when ripening; leaflets with spreading or appressed hairs on both surfaces; terminal leaflet sessile or subsessile, elliptic to broadly obovate, obtuse to rounded, cuneate, larger than other leaflets, 2–5 cm long, 1.5–4 cm wide when flowering; petiole slender, pilose, 1/2–1/3 of leaf length; stipule membranaceous, adnate to petiole in lower half, lanceolate, acute, pilose on outside and margin. Peduncles from axils of scaly leaves on rhizomes, 7–18 cm long with spreading or ascending hairs, 3–10 flowers composing cymes-like inflorescences. Flowers 5-merous in dichasium, hermaphroditic, actinomorphic, 1–1.8 cm across; outer calyx segment oblong to lanceolate, acute, entire, 4.5–7 mm long, 2.5–3 mm wide, pilose outside, inner calyx 5, narrower slightly than outer; petals yellow, elliptic to obovate, 6.6–9 mm long, 6–8.8 mm wide, apex rounded or retuse; stamens 20, 2.8–4.2 mm long, anthers ovate ellipsoid, ca. 1.4 mm long, ca. 0.7 mm wide; pistils numerous on dome-shaped, white pilose receptacle; ovary glabrous, style lateral. Fruits achenes, oblong-ovoid, glabrous, 1–1.2 mm long.

Flowering: April to June.

Distribution: Endemic to Korea; Chungcheongbuk-do, Gangwon-do, Gyeonggi-do, Gyeongsangbuk-do, Seoul.

Specimens examined: KOREA. Chungcheongbuk-do: Goisan-gun, Mt. Baekhwasan, 31 May 2003, S.H. Kim et al. (KH). Gangwon-do: Chuncheon-si, Jiam-ri, Mt. Hwaaksan, 15 May 1998, Y.D. Kim & J.H. Lee (KB); Inje-gun, Bukmyeon, Yongdae-ri, Sibiseonnyeotang valley, 26 Apr 2002, Y.D. Kim & D.H. Kwak 505 (KB); Sangnam-myeon, Misan-ri, Mt. Gaeinsan, 12 May 2004, H.S. Choi et al. (KH); Jeongseon-gun, Jeongseon-eup, Hoedong-ri, Eoeundong, Mt. Gariwangsan, 24 Apr 2008, C.E. Lim, M.H. Kim & S.J. Lee (KB); 16 Jun 2022, H.T. Im 223624 (CNU); Sabuk-myeon, Sabuk-eup, Duwibong, 18 May 2013, H.T. Im 130662 (CNU); Pyeongchang-gun, Jinbu-myeon, Mt. Odaesan, 10 May 1998, C.W. Park, H.W. Lee & S. J. Lee 10125 (KB); Samcheok-si, Miro-myeon, forest genetic resource reserve, 16 May 2011, K.S. Lee et al. (KH); Samsu-dong, Eundaebong, 22 May 2008 (KH); Taebaek-si, Hasami-dong, Guinemi, Mt. Deokhangsan, H.T. Im 221216 (CNU); Hwangji-dong, Jungbong-ri, Mt. Hambaeksan, 14 Sep 2022, H.T. Im 222586 (CNU); Hwanjeon-dong, Eundaebong, 17 Jun 2022, H.T. Im 223398 (CNU); Hyeon-dong, Mt. Taebaeksan, 31 May 2008, B.U. Oh et al. (KH); Wonju-si, Mt. Chiaksan, Birobong, 18 May 1999, J.D. Chung (KB); Yangyang-gun, Seo-myeon, Galcheon-ri, Guryong-ryeong, 6 May 2011, U.H. Im & J.C. Sim (KB); 6 May 2010, J.S. Jang & J.A. Lee (KB); Osaek-ri, Daecheongbong, 17 May 2002, Y.D. Kim & D.H. Kwak (KB); 4 Jun 2010, J.H. Kim, J.H. Yun & M.S. Kwon (KB). Gyeonggi-do: Gapyeong-gun, Gapyeong-eup, Seungan-ri, Mt. Yeoninsan, 26 Apr 2014, W.B. Lee (KB). Gyeongsangbuk-do: Bonghwa-gun, Mulya-myeon, Ojeon-ri, Mt. Seondalsan, 3 May 2008, G.Y. Chung & M. S. Park (KB); Chunyang-myeon, Mt. Guryongsan, 2 May 2008, G.Y. Chung & M. S. Park (KB). Seoul, Dobong-gu, Mt. Bukhansan, 21 Jun 1997, D.H. Kim & S.K. Kwon KNAH 013207 (KH).

With regard to type locality (Duwibong; Gangwon-do, Sabuk-myeon, Sabuk-eup), P. rhizoma is commonly found on half-shaded forest margins along mountain trails under deciduous forests dominated by Quercus mongolica Fisch. ex Ledeb., Carpinus tschonoskii Maxim., Acer pseudosieboldianum (Pax) Kom., Betula schmidtii Regel, and Fraxinus sieboldiana Blume, with accompanying species such as Sorbus commixta Hedl., Aria alnifolia (Siebold & Zucc.) Decne. and Styrax obassia Siebold & Zucc. Certain perennial herbs, such as Waldsteinia ternata (Stephan) Fritsch, Viola albida Palib., V. rossii Hemsl., Clintonia udensis Trautv. & C. A. Mey., Anemone raddeana Regel, A. reflexa Steph. ex Willd., Primula sieboldii E. Morren, Corydalis remota Fisch. ex Maxim., Geranium platyanthum Duthie, Oxalis obtriangulata Maxim., and Iris minutoaurea Makino are also seen on the forest floor.

An identification key for Korean Potentilla species with pinnate leaves, scapose stems, and flowers on terminal cymes is given below.

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