おおばうまのすずくさ (大葉馬の鈴草) [Index] [Back] わが国の本州、関東地方から中国地方の太平洋側、および四国・九州に分布しています。低山の山林に生え、蔓は木化して他の草木に絡みつき、高さは２〜３メートルになります。葉は円心形、広卵形、三角状心形で基部は心形です。またしばしば３裂して両側裂片が円形の耳状になり、中央裂片が細長くなるものもあります。５月から６月ごろ、葉腋に花を１個、まれに２個咲かせます。花弁はなく、３個の萼が合着して萼筒を形成します。萼筒は ふつう黄緑色で，赤褐色から濃紫色の条紋があり、しばしば全体または下部が網目状になります。まれに全体が濃紫色またはクリーム色となるものもあります。萼筒の内面は黄緑色で、紫褐色の斑点が密にあるか、あるいは斑点はなく紫褐色になるものもあります。果実は広楕円形からやや長い楕円形の�刮ﾊです。 ウマノスズクサ科ウマノスズクサ属の蔓性落葉木本で、学名は Aristolochia kaempferi (syn. Isotrema kaempferi)。英名はありません。 The "Ooba-umano-suzukusa" (Aristolochia kaempferi) belongs to Aristolochiaceae (the Birthwort family). It is a climbing deciduous shrub that is distributed across Japan's Honshu Island, from the Pacific coast of the Kanto region to the Chugoku region, as well as in Shikoku and Kyushu. It grows in the forests of low mountains; its vines become woody and entwine with other plants, reaching a height of 2 to 3 m. The leaves are rounded-cordate, broadly ovate, or triangular-cordate, with a cordate base. Some leaves are often three-lobed, with the lateral lobes forming round, ear-like structures and the central lobe becoming elongated. From around May to June, it produces one flower-rarely two-in each leaf axil. It has no petals; instead, three sepals are fused to form a calyx tube. The calyx tube is usually yellowish-green, with reddish-brown to deep purple stripes, and often has a net-like pattern over its entire surface or lower portion. Rarely, the entire calyx tube may be dark purple or cream-colored. The inner surface of the calyx tube is yellowish-green; some specimens have dense purplish-brown spots, while others are uniformly purplish-brown without spots. The f 宮城県仙台市太白区秋保町馬場「秋保大滝植物園」にて、2026年07月28日撮影。 Shu Suehiro shu@botanic.jp