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Korean J. Pl. Taxon > Volume 50(2); 2020 > Article
JEONG, KIM, JO, PARK, LEE, JI, and CHUNG: Taxonomic identity of Dioscorea coreana (Prain & Burkill) R. Kunth


The identity of Dioscorea coreana (Prain & Burkill) R. Kunth is recognized during the re-identification process of Korean Dioscorea specimens. Given the relatively few pieces of information, including few descriptions and research papers, this species has been misidentified as D. tokoro, which has a similar leaf shape, but D. coreana is distinguished from D. tokoro by the absence of a pedicel in the male flower, the green color of the tepal, and the shapes of the fruit and seed. Thus, detailed descriptions, illustrations, and photographs of D. coreana and a key to the Korean Dioscorea, including this species, are presented.

Dioscorea L. belongs to Dioscoreaceae of Liliales, and ca. 600 species of this genus are distributed mainly in tropical regions, East Asia, the Mediterranean coast, and North and South America (Coursey, 1969; Li et al., 1978; Ohwi, 1984; Im, 2000; Lee, 2006). The species of this genus had been described first by Linnaeus (1753) as a morphological difference of leaves, and the type of underground parts, the presence of bulbil, the shape of the leaves and flowers, the shape of the fruits and seeds had been treated as the main traits of the taxa among the genus (Knuth, 1850; Beccari, 1870; Engler and Prantl, 1897; Burkill, 1960). Recently, molecular research using DNA sequences have led to the debate about the relationships and evolutionary trends among the taxa in the genus (Wilkin et al., 2005; Gao et al., 2008; Hsu et al., 2013; Gawande et al., 2015).
After D. tenuipes Frnach. & Sav. had been recorded first by Palibin (1901), eight species of Dioscorea, D. polystachya Turcz., D. japonica Thunb., D. nipponica Makino, D. quinquelobata Thunb., D. tokoro Makino ex Miyabe, D. septemloba Thunb., D. bulbifera L., are distributed in Korea (Lee, 2003; Lee, 2006; Oh and Lee, 2007), but the habitats of D. septemloba Thunb., and D. bulbifera L. is unclear in Korea (Chung and Chung, 2016).
Conversely, Dioscorea coreana (Prain & Burkill) R. Kunth is recognized as an accepted name and distributed in Korea on Internet search sites of the scientific name (e.g., http://plantsoftheworldonline.org, http://www.theplantlist.org, http://gbif.org, etc.), but this species was only mentioned as the scientific name D. coreana Kunth by Lee (1976). Also, this species is called Pu-Reun-Ma as a common name without taxonomic reviews (Kim et al., 2016; Chung et al., 2017; KNA, 2017; Kim et al., 2019). But the identity of D. coreana is recognized during the re-identification process of the Korean Doiscorea specimens. Thus, the purpose of this study was to provide detailed descriptions, illustrations, and photographs of the taxa and a key of Korean Dioscorea including this species.

Taxonomic Treatment

Dioscorea coreana (Prain & Burkill) R. Kunth in Engl., Pflanzenr. 87: 175, 1924.
Disocrea villosa L. var. coreana Prain & Burkill, J. Proc. Asiat. Soc. Bengal 10: 15, 1914.─TYPE: Korea. Prov. Incheon, May 1884, W. R. Carles 178 (holotype: K!).
Herbs unisexual, perennial, vine, dioecious. Rhizomes horizontal, subcylindrical. Roots fibrous, came out from lower side of rhizomes. Stems twining to left, grooved, smooth. bulbils absent. Leaves alternate, rarely whorled, unicellular hair, petiole 5.3–9.3 cm long, base non-protuberance; leaf blade cordiform, 5.9–8.6 × 4.3–7.7 cm, apex acuminate, base cordate. margin entire. Male Inflorescences spike, 4.6–9.2 cm long, absent pedicel. Female Inflorescences spike, 4.1–7.5 cm long, absent pedicel. Male Flowers green, 1.6–2.1 × 3.3– 4.2 mm; outer tepals narrowly-ovate, 2.2–2.5 × 1.2–1.5 mm; inner tepals narrowly-ovate, 2.1–2.5 × 1.1–1.5 mm; stamens 6, 0.7–0.9 × 0.1–0.2 mm; anther 0.5–0.6 × 0.2–0.3 mm, in frank position. Female Flowers green, 2.0–2.6 × 2.4–3.2 mm; outer tepals narrowly-ovate, 1.5–2.0 × 0.9–1.2 mm; inner tepals narrowly-ovate, 1.4–2.0 × 0.8–1.2 mm; ovary 4.4–5.2 × 1.3–1.9 mm; staminodes 6; pistil 3-lobed, 0.7–0.9 × 0.6– 0.9 mm; stigma not cracked. Fruits capsule, ovate-globose, erect, 3-winged, 21.5–25.1 × 25.5–30.5 mm. Seeds 4.5–5.8 × 3.8–4.5 mm, situated at center of the membranous wing; wings 8.8–11.2 × 14.1–16.1 mm, hemispheric.
Korean name: Pu-Reun-Ma (푸른마).
Flowering: May to Jun.
Fruiting: Jun to Jul.
Distribution: Restricted to Korea.
Korea: Endemic (Gyeonggi-do, Gangwon-do, Gyeongsangbuk- do, Chung-cheongnam-do).
Specimen examined: KOREA. Gyeonggi-do: Maoksan Mt., 26 May 2007, G. Y. Chung et al., ANH-0009175 (ANH), Paldalsan Mt., 31 May 1967, T. B. Lee, 00072835 (SNUA). Gangwon-do: Jangseongsogak-Park, 28 May 2010, S. H. Cho and Y. I. Kim, YoungdongKim 2010-0029 (HUH), Deungseonfalls, 27 May 1995, H. G. Lee et al., 0003645 (HUH), Yonghwasan Mt., 30 May 1998, D. M. Choi et al., 0003644 (HUH), Geumbyeongsan Mt., 19 Jun 2007, G. E. Yu, 063114 (KWNU), Hugogyaksu, 4 Jun 1999, C. S. Chang, 00070596 (SNUA), Cheongnyeongpo, 13 Aug 2004, J. M. Chung et al., 04080073 (KH), Garisan Mt., 15 Jun 2011, K. O. Yoo et al., koyoo0118 (KH). Chungcheongbuk-do: Guryongsan Mt., 17 May 1997, B. U. Oh et al., 07317 (CBU), Geumdangsan Mt., 22 May 1999, C. S. Chung et al., 04202 (CBU), Gaseopsan Mt., 30 Apr 2000, S. H. Paeng et al., 04204 (CBU), Dutasan Mt., 25 May 2002, B. U. Oh et al., 04206 (CBU), Seondosan Mt., 31 May 1997, B. U. Oh et al., 08908 (CBU), Ingyeongsan Mt., 21 May 2011, B. U. Oh et al., 22620 (CBU), Sosokisan Mt., 13 May 2005, B. H. Oh et al., eumseonggun (sosogisan)-0505 (KH). Chungcheongnam-do: Sanan-ri, 11 Jun 2006, E. S. Jeon, esjeon60608 (KH). Gyeongsangbuk-do: Podosan Mt., 7 Jul 2007, G. Y. Chung et al., ANH-0001504 (ANH), Muposan Mt., 2 Oct 2010, G. Y. Chung et al., ANH-000012103 (ANH), Joosan Mt., 20 May 1999, D. R. Choi and S. G. Kwon, 00072844 (SNUA), Bibongsan Mt., 6 Aug 2000, S. W. Lee et al., 218 (KNU), Gallasan Mt., 6 Jun 2008, M. S. Park, ANH-000014010 (ANH), Maengdongsan Mt., 28 Aug 2006, G. Y. Jeong, Jeong210 (KH), Jachosan Mt., 13 May 2010, G. Y. Chung et al., ANH-100513125 (ANH).
Taxonomic note: After being recorded as Dioscorea sp., based on the specimen (Carles, 178) collected in May 1884 at Incheon Chemulpo by Wright (1903), D. coreana was reported as Dioscorea sp. by Nakai (1911), who cited Wright’s statement. Later, this taxon was reported as D. villosa var. coreana by Prain and Burkill (1914), because this taxon was similar to D. villosa, but the fruits of this taxon had a patternless, shiny trait. But D. coreana as a new combination name was announced by Kunth (1924). Since then, only the scientific name has been mentioned by Lee (1976), there is no mention of this species in books and papers at home and abroad. In the studies of Korean Dioscorea (Kang et al., 1992; Oh et al., 1995, 1996; Chung and Chung, 2016), D. coreana may be misidentified as D. tokoro. The reason for the misidentification is because the two species have a relatively similar leaf as heart shape and morphological information of D. coreana was scant except for the original description. In this study, D. coreana is distinguished from D. tokoro by the absence of the pedicel in the male flowers, the green color of tepal, the ovate-globose shape of the fruit, and the hemispherical shape of the membranous wing surrounding the seeds (Table 1, Figs. 1, 2, 3).
After checking the voucher specimens in the domestic herbaria to confirm the distributional information of D. coreana and D. tokoro, D. coreana has been found to grow natively in Gyeonggi, Gangwon, Chungbuk, Chungnam, and Gyeongbuk but not in Gyeongnam, Jeonbuk, Jeonnam, and Jeju (Fig. 4). Conversely, D. tokoro was unable to confirm the distribution in Korea. Some specimens of D. tokoro are identified as D. coreana, and the other specimens from southern region are identified as D. polystachya or D. tenuipes. Considering the geographical characteristics of China and Japan (Ding and Gilbert, 2000; Iwatsuki et al., 2016) around the Korean Peninsula, D. tokoro may be distributed in Korea. So if this is considered, the distributional surveys of D. tokoro are needed.

Key to Korean Dioscorea L

  • 1. Rootstock vertical, tuber, bulbil

    • 2. Leaves deltate, male flower peduncle zigzagged, fruit 16.6–17.9 mm wide ·················· D. polystachya

    • 2. Leaves triangular, male flower peduncle straight, fruit 24.6–29.5 mm wide ··················· D. japonica 참마

  • 1. Rootstock horizontal, rhizome, non-bulbil

    • 3. Protrude papillae at axillary

      • 4. Leaves 1–4 pair lobed, tapal non-reflexed-shape ······································· D. quinquelobata 단풍마

      • 4. Leaves margin entire, tapal reflexed-shape ··········· ·················································· D. tenuipes 각시마

    • 3. Non protrude papillae at axillary

      • 5. Leaves 1–4 pair lobed ······· D. nipponica 부채마

      • 5. Leaves margin entire

        • 6. Male inflorescence raceme, present pedicel on the male flower, flower color yellowish, seeds situated at base of the membranous wing ····· ········································· D. tokoro 도꼬로마

        • 6. Male inflorescence spike, absent pedicel on the male flower, flower color green, seeds situated at center of the membranous wing ················· ·········································· D. coreana 푸른마


Authors thank the anonymous reviewers for their valuable comments and suggestions. This study was supported by a research grant of Andong National University (2019).


Conflict of Interest
The authors declare that there are no conflicts of interest

Fig. 1.
Photographs of Dioscorea coreana (Prain & Burkill) R. Kunth. A. Habit. B. Rhizome. C. Flower (♂). D. Flower (♀). E. Fruit. F. Seed.
Fig. 2.
Illustrations of Dioscorea coreana and D. tokoro. A–G. D. coreana. A. Habit. B. Rhizome. C. Flower (♂). D. Flower (♀). E. Stamen. F. Fruit. G. Seed. H–J. D. tokoro. H. Flower (♂). h, male inflorescence pedicel. I. Fruit. J. Seed.
Fig. 3.
Holotype of Dioscorea coreana and D. tokoro. A. D. coreana (Prain & Burkill) R. Kunth (in K herbarium). B. D. tokoro Makino ex Miyabe (in DAO herbarium). C. Label of D. coreana. D. Label of D. tokoro.
Fig. 4.
Distribution of Dioscorea coreana (Prain & Burkill) R. Kunth in Korea.
Table 1.
Comparison of morphological characters between Dioscorea coreana and D. tokoro.
D. coreana Spike Absent Green Ovate Ovate-globose Center Hemispheric
D. tokoro Raceme Present Yellowish Obovate Obovate-elliptic One-side Eliptical

MI, male inflorescence; MIP, male inflorescence pedicel; FC, flower color; TS, tepal shape; SPW, seed position wing; WS, wing shape.

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