A new record of <i>Rhododendron keiskei</i> Miq. var. <i>hypoglaucum</i> Suto & Suzuki (Ericaceae) in Korea

Jong-Cheol Yang; Yeong-Han Kwon; Seong-Jin Ji; Chang-Ho Shin

doi:10.11110/kjpt.2015.45.3.239

적 요

진달래과의 Rhododendron keiskei Miq. var. hypoglaucum Suto & Suzuki가 전라남도 여수시 섬지역에서 발견되었다. 이 종은 전체적으로 인편상 털이 분포하며, 꽃의 동아는 정단부에 1개가 달리고, 화서는 산형총상화서를 가지며, 화관은 노란색을 띠는 백색에 외부에는 인편상 털이 있는 특징을 가지고 있어 한국에 분포하는 근연 분류군들과 구분된다. 국명은 생육지를 고려하여 ‘섬진달래’로 신칭하였고, 이에 대한 기재, 도해, 사진 및 검색표를 제시하였다.

주요어: 섬진달래, 진달래과, 미기록, 한국

Abstract

Rhododendron keiskei Miq. var. hypoglaucum Suto & Suzuki (Ericaceae) was found in Yeosu-si, Jeollanam-do, Korea. This species is distinguished from related taxa in Korea by lepidote hairs entire, flower-bud terminal, inflorescences umbel-like racemes, corolla lepidot outside, white tinged with yellow. This taxon was named ‘Seom-Jin-Dal-Lae’ in Korean based on its habitat. We provide its description, illustrations, photographs and a key of related taxa in Korea.

Keywords: Rhododendron keiskei var hypoglaucum, Ericaceae, new record, Korea

Rhododendron Linnaeus (Ericaceae Juss.) includes about 1,000 taxa and is widely distributed in Asia, Europe, North America (Fang et al., 2005). Since the gnus was established by Linnaeus, its infrageneric relationships have been well studied by many taxonomists. Sleumer (1949) divided the genus into 8 subgenera and Cullen (1980) and Chamberlain (1982) divided it into 5 subgenera. Resently Fang et al.(2005) and Yamazaki (1996) divided it into 9 subgnera.

Twenty three taxa of Rhododendron are distributed in the wild in korea(Korea National Arboretum et al. 2014). During an expedition to the south island in korea, We found an unrecorded species of Rhododendron. This species is characterized by evergreen and entire leaves with lepidote hairs, flower-bud terminal and single, flower white tinged with yellow. After studying the unidentified specimen and literature, we concluded it represents Rhododendron keiskei Miq. var. hypoglaucum Suto & Suzuki within section Rhododendron of subgenus Rhododendron (Yamazaki, 1996). So far it has been a endemic plant of Japan. In this study, Rhododendron keiskei Miq. var. hypoglaucum Suto & Suzuki is reported as a newly founded taxon in Korea. In addition, we provide its description, illustrations, photographs and a key of related taxa.

Description

Rhododendron keiskei Miq. var. hypoglaucum Suto & Suzuki in Trans. Nat. Hist. Soc. Formos. 22: 23 (1932)

Dwarf evergreen shurbs 30–50 cm tall (rarely 2 m). Lepidote hairs entire. Leaves elliptic to elliptic-oblong, 2–5.5 cm long, 1–2.5 cm wide, obtuse or subacute at apex, glaucous beneath. Flower-bud terminal, single (rarely 2–3), oblong-ovate. Inflorescences umbel-like racemes, with 2–6 flowers. Corolla white tinged with yellow, funnel-shaped, ca. 2.5 long, 3 cm wide, sparsely lepidote outside. Stamens 10–12, irregular, similar or slightly longer than corolla. Ovary oblong-lanceolate, densely lepidote. Style slightly curved, longer than corolla, glabrous. Capsule cylindric, straight, 10–13 mm long, 2–3mm wide, densely lepidote. Seeds oblong, ca. 1 mm long, with a short appendage on an other side (Figs. 1, 2).

Korean name: Seom-Jin-Dal-Lae (섬진달래).
Flowering: April to May
Distribution: Japan (Honshu) and Korea (Samsan-myeon, Yeosu-si).
Voucher specimens: Korea, Jeollanam-do, Yeosu-si, Samsan-myeon, 16 May. 2012, S. J. Ji 12051401 (3 sheets, KH); 15 Apr. 2015. J. C. Yang 15041501 (5 sheets, KH).

Note: R. keiskei var. hypoglaucum is very similar to R. lapponicum subsp. parvifolium (Adams) T.Yamaz. among Korean Rhododendron. But the former is distinguished from the latter by having leaves more than 2 cm and corolla lepidote outside, white. it was found in south island of korea and mostly grows at rock cliffs on mountain. We could not exactly count the number of R. keiskei var. hypoglaucum due to the rugged terrain. But We guess there are hundreds of it in habitat. It was usually found on the north slope of the island and in the evergreen bushes together with Raphiolepis indica var. umbellata (Thunb.) Ohashi, Ligustrum japonicum Thunb., Camellia japonica L, Litsea japonica (Thunb.) Juss. etc. In Japan this species have a very limited distribution at Honshu (Kanto) (Yamazaki, 1996; Ministry of the Environment, 2012a) (Fig. 3). Ministry of the Environment (2012b) reported that R. keiskei var. hypoglaucum is assumed less than 200 individual in Japan. This species was named ‘Seom-Jin-Dal-Lae’ in Korean based on its habitat.

A key to R. keiskei var. hypoglaucum and its related taxa

1. Flower-buds clustered in axils of approximate upper leaves or scales, each bud generallly producing a single flower ······ R. mucronulatum (진달래), R. dauricum (산진달래)
1. Flower-buds terminal, producing an umbel-like or croymbose inflorescence
- 2. Inflorescences with 1–6 flowers in umbel-like racemes; corolla zygomorphic
  - 3. Leaves more than 2 cm long(shorter in R. keiskei var. ozawae); corolla lepidote outside, white or yellow
    
    4. Leaves oblong or oblong-lanceolate, apex acuminate, 3–9 cm long, pale green beneath ·················································································· R. keiskei var. keiskei
    
    4. Leaves elliptic, apex obtuse to subacute, glaucous beneath
    
    5. Branches ascendent, 30–50 cm tall; leaves 2–4 cm; cololla white tinged with yellow ······························ ·············· R. keiskei var. hypoglaucum (섬진달래)
    
    5. Branches divaicate, 10–20 cm tall; leaves 1.5–2.5 cm long; corolla yellow ············ R. keiskei var. ozawae
    
    3. Leaves less than 2 cm long; corolla glabrous outside, violet ···· R. lapponicum subsp. parvifolium (황산차)
- 2. Inflorescences with 10–30 flowers in corymbose racemes; corolla actinomorphic ················································································· R. micranthum (꼬리진달래)

한국 미기록 식물: 섬진달래(진달래과)

A new record of Rhododendron keiskei Miq. var. hypoglaucum Suto & Suzuki (Ericaceae) in Korea

적 요

Abstract

Description

A key to R. keiskei var. hypoglaucum and its related taxa

ACKNOWLEDGMENTS

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Literature Cited