りゅうきゅうがしわ (琉球柏) [Index] [Back] わが国の固有種で、宮古群島から八重山群島に分布しています。日当りのよい原野や海岸の岩上に生え、蔓性で茎は長さ数メートルになります。葉は卵形から卵状楕円形、縁は全縁で対生します。葉柄は長さ１〜２センチ、基部には葉状托葉が１対あります。ほとんど一年中、葉腋に総状花序をだし、帯黄紫色の花を咲かせます。果実は、披針状長楕円形の袋果です。本種は、アサギマダラの食草として有名です。 ガガイモ科カモメヅル属の多年草で、学名は Cynanchum liukiuense。英名はありません。 The "Ryukyu-gashiwa" (Cynanchum liukiuense) belongs to Asclepiadaceae (the Milkweed family). It is a perennial herb that is an endemic species to Japan, distributed from the Miyako Islands to the Yaeyama Islands. It grows in sunny open fields and on coastal rocks; it is a vine with stems reaching several meters in length. The leaves are ovate to ovate-elliptic, with entire margins, and are arranged in opposite pairs. The petioles are 1-2 cm long, and there is a pair of leaf-like stipules at the base. It produces racemose inflorescences in the leaf axils almost year-round, bearing yellowish-purple flowers. The fruit is a lanceolate-oblong capsule. This species is well known as a food plant for the Chestnut tiger (Parantica sita). 茨城県つくば市「つくば実験植物園」にて、2026年03月28日撮影。 Shu Suehiro shu@botanic.jp