The wild Citrus is hitherto very imperfectly known from the Japanese territories, though this region is generally believed to be one of the native homes of this important genus of Rutaceae. The author has repeatedly reported that Citrus taci bana TANAKA is native to Japan proper, covering the southern coasts of provinces Kii, Tosa, Hyuga, Osumi and Satsuma. Recently, its southern limit of occurence was found in the island of Sanbok (Amami Oshima), where the second wild species begins to appear. It was lately discovered that the same species (possible a veriety) occurs wild in Nagato province and in Querpert Island (Saishuto). In the main i s land of Luchu (Okinawa), a very remarkable wild species is known under the name of Suikwasha, and through the closer examination of Formosan Citrus, this was identified by the author to be Citrus depressa HAVATA, first described from Gaogan, Taihoku province. This second wild species was later found to distribute all over the Luchu Archipelago south of Sanbok. Noticeably, this species is connected ethnologically with the inhabitants of the island, just as the first species does with the forefathers of Japan proper. In Taiwan, Citrus tankan HAVATA is found in the myths of aborigines, and it does occur in the woods where they make use of it. It is not found in South China in any degree of primitive state, but is rather extensively cultivated for shipping purpose. There is another distinct species growing wild in the forests of Gaogan and Nansho (Shinchiku province), which is here described as a new species, Citrus taiwanica TANAKA & SHIMADA n. sp. This species is nearest to the sour orange, but is very distinct with its remarkably long leaves, medium-sized flat fruits with finely dotted leathery skin, and very acid deep-yellow pulp. Citrus gaoganensis HAYATA, reported wild from Gaogan, is n othing but an albino citron escaped from cultivation, and may preferably be called Citrus ,medica gaoganensis n. comb.
1.日本領土の第一野生柑橘はタチバナ Citrus tachibana TANAKA in Bul. Sci. Fak. Ter. Kyu. Imp. Univ. 1 no. 1 : 31, 1924 にして其分布は紀伊・土佐・日向・大隅・薩摩・濟州島・奄美大島等なり。2. 日本領土の第二野生柑橘はシークワシヤー Citrus depressa HAYATA in Icon. Pl. Form. 8 : 16, 1919 にしてヒラミレモンは其異名なり。本種の分布は奄美大島・沖之永良部・沖繩本島・石垣島・西表島・八重山群島中鳩間島・與那國島及臺灣北部等なり。3. 桶柑(即年柑) Citrus tankan HAYATA l.c. p. 26 は甜橙に近き臺灣在來種にして野生状態に生育するを見る。臺灣以外に於ては對岸支那に栽培を見るも原始的状態に於て存する事なく, 其他の地には全然栽培すらなし。4. 以上の三種は敦れも民族傳説と深き關係あり, 即其原始的存在の證たり。5. 臺灣北部に於て新檢出の野生柑橘南庄ダイダイ Citrus taiwanica TANAKA & SHIMADA n. sp. はダイダイに最も近き一新種にして長き葉と, 扁き中形果と, 革質油胞細密なる外皮と, 濃黄多酸の果肉を以て特長となす。現時は稀少にして僅にガオカシ及南庄のニケ所に於て發見せしのみなり。6. 本研究に據りて柑橘屬果樹の地理學上日本西南部・濟州島・沖繩列島・及臺灣を明瞭なる其郷土として加ふる事を得たり。