おのおれかんば (斧折れ樺) [Index] [Back] わが国の本州、中部地方以北のおもに太平洋側、および朝鮮半島や中国東北部、ウスリー地方に分布しています。岩礫地や尾根などに生え、高さは１５メートルほどになります。樹皮は黒褐色から灰褐色で、老木になると亀甲状に割れます。葉は長卵形で先端は鋭く尖り、縁には不揃いの細かい鋸歯があります。葉は秋に黄葉します。５月ごろ、葉の展開と同時に開花します。雄花序は枝先に下垂し、雌花序は短枝の先に直立します。果実は堅果で、果穂は２〜４センチの円柱形で上向きにつき、９月から１０月に成熟します。和名は、材か堅くて斧さえ折れるという意味から。中国語では「賽�K樺（sai hei hua）」と呼ばれます。韓国語では「バクダルナム（朴達木: 박달나갬）」です。 カバノキ科カバノキ属の落葉高木で、学名は Betula schmidtii。英名はありません。 The "Ono-ore-kanba" (Betula schmidtii) belongs to Betulaceae (the Birch family). It is a tall decidous tree that is distributed primarily along the Pacific coast of Japan's Honshu Island, from the Chubu region northward, as well as on the Korean Peninsula, in northeastern China, and in the Ussuri region. It grows in rocky areas and along ridges, reaching a height of about 15 m. The bark is blackish-brown to grayish-brown and cracks into a tortoiseshell pattern as the tree ages. The leaves are long-ovate with sharply pointed tips and irregular, fine serrations along the margins. The leaves turn yellow in the fall. Flowering occurs around May, coinciding with the unfolding of the leaves. Male inflorescences hang downward from the tips of branches, while female inflorescences stand upright at the tips of short branches. The fruit is a nut; the catkins are cylindrical, 2 to 4 cm long, and point upward, ripening from September to October. The Japanese name derives from the fact that the wood is so hard it can even break an axe. In Chinese, it is called "賽�K樺" (sai hei hua). In Korean, it is known as "Bak-dal-namu: 박달나갬". 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08月25日撮影。 Shu Suehiro shu@botanic.jp