Asarum koreanum J. Kim et C. Yook ex B.U.Oh, 2020

Oh, Ami, Leem, Hyosun & Oh, Byoung-Un, 2020, Asarum koreanum (Aristolochiaceae), a new species from Korea, Phytotaxa 429 (2), pp. 173-178 : 174-177

Asarum koreanum J. Kim et C. Yook ex B.U.Oh , sp. nov. ( Figs. 1 , 2 , 3 )

Type:— KOREA. Chungcheongbuk-do: Eumseong-gun, Mt. Gaseopsan, shady forest or forest edge in mountainous region, 563 m, 36°57’54” N, 127°42’03” E, 4 May 1997, B. U.Oh et al., 970504-1 (holotype CBU!, isotype CBU!).

Diagnosis:— Asarum koreanum is morphologically similar to A. sieboldii , but is distinguished by purple leaves, larger flowers, and deep purple calyx lobes with dense multicellular glandular trichomes ( Table 1).

Perennial, 19.2–32.5 cm tall. Rhizomes creeping, ivory to whitish purple, 3.1–16.5 cm long, 1.4–4.4 mm in diam. Cataphylls entire, trichomes on margin, whitish purple, 2–4; first scale 8.5–15.6 mm long, 7.8–13.3 mm wide; second scale 5.0– 9.8 mm long, 6.0– 9.7 mm wide. Leaves alternate, simple, paired in an individual with flower; petiole slightly haired, whitish purple to purple, 14.1–21.4 cm long, 1.4–2.8 mm in diam.; leaf blade cordate or ovate-cordate, apex acute or acuminate, margin entire, base cordate, 6.4–16.7 cm long, 5.5–15.2 cm wide; adaxial surface pubescent, with short hairs, purple to purplish green or green, purple to yellowish green on vein, variegation not observed; abaxial surface short haired on vein, purple or pale green. Inflorescence solitary; peduncle glabrous, purple or whitish purple, 9.4–11.5 cm long, 0.3–2.4 mm in diam. Flowers actinomorphic; calyx tube campanulate or cup-shaped, 12.3–14.7 mm long, 13.4–14.9 mm in diam.; outer surface pale brown; inner surface vertical ridge, purple; calyx lobes 3, deltoid and undulate, apex acuminate or cuspidate, not recurved, dark purple, 8.8–17.8 mm long, 9.6–15.3 mm wide; stamens 12; filaments slightly flattened, whitish purple, 2.7–3.1 mm long, 0.6–0.7 mm wide; anthers extrorse, oblong, yellow, 1.6–1.8 mm long; ovary superior, placentation axilary, locules 6; styles radial, purple, 0.9–1.3 mm long, protuberance 1.3–1.6 mm tall, 1.5–1.9 mm long; stigmas lateral, roundish and convex. Fruits a fleshy capsule, irregularly dehiscent when ripe. Seeds numerous, slightly curved, light brown, with whitish brown appendage, 3.3–3.8 mm long, 1.8–2.0 mm in diam.

Distribution and habitat:—The distribution of A. koreanum is restricted to the central region of Korea (Chungcheongbuk-do), including Mt. Gaseopsan, Mt. Gunjasan, Mt. Baegaksan, Mt. Wolaksan, Mt. Songnisan, Mt. Samtaesan, and Mt. Yongsanbong. The populations were found in shady forest or forest edge.

Phenology:—Flowering is observed from April to June, and fruiting from June to August.

Chromosome number:— Asarum koreanum has 2 n =26 chromosomes.

Additional specimens examined: — KOREA. Chungcheongbuk-do: Danyang-gun Samtaesan , 20 April 2012, K. O.Yoo et al., 86066 ( KWNU!) ; Danyang-gun Yongsanbong , 19 April 2012, K. O.Yoo et al., 85240 ( KWNU!) ; Boeun-gun Songnisan , 21 May 2005, K. O.Yoo et al., 74821 ( KWNU!) .

Specimens examined for Asarum sieboldii : — KOREA. Chungcheongbuk-do: Boeun-gun Gubyeongsan, 25 May 2013, B. U. Oh et al., Boeun-gun (gubyeongsan)-130525-317 ( CBU!). Jeollanam-do: Gurye-gun Imgeollyeong , 29 May 2010, B. U. Oh et al., 100529-imgeollyeong-002 ( CBU!) ; the same locality, 29 May 2010, B. U. Oh et al., 100529-imgeollyeong-011 ( CBU!) ; the same locality, 29 May 2010, B. U. Oh et al., 100529-imgeollyeong-024 ( CBU!). Gyeongsangbuk-do: Sangju-si Jungbeol-ri, 25 May 2013, B. U. Oh et al., Sangju-si (baekbaegaksan)-130525-108 ( CBU!) ; the same locality, 25 May 2013, B. U. Oh et al., Sangju-si (baekbaegaksan)-130525-112 ( CBU!) ; the same locality, 25 May 2013, B. U. Oh et al., Sangju-si (baekbaegaksan)-130525-121 ( CBU!) .

Figures

FIGURE 1. The difference in the density of the glandular trichomes on the adaxial surfaces of the calyx lobes between Asarum koreanum and Asarum sieboldii. A1–A2. A. sieboldii; B1–B2. A. koreanum. (Photographs: Hyosun Leem; modified from Leem & Oh 2019).

FIGURE 2. Holotype of Asarum koreanum B.U.Oh, B.U.Oh 970504-1 (CBU).

FIGURE 3. Morphological characteristics of Asarum koreanum. A. Habit; B. Rhizome; C. Leaf (adaxial); D. Leaf (abaxial); E. Cataphyll; F. Apical view of flower; G. Lateral view of flower; H. Pistil and stamen; I. Seed (Photographs: Hyosun Leem).