Ash tree - Toneriko

A deciduous tree of the Oleaceae family (APG classification: Oleaceae). It grows to a height of 6-15 meters. The bark is smooth and grayish white, and the branches are thick. The leaves are opposite, odd-pinnate, and compound, 20-30 cm long. There are 5-9 leaflets, ovate or oblong, 5-15 cm long, pointed at the tip, and shallowly serrated edges. The mid-vein on the underside has white hairs that spread out, and the nodes where the leaflets attach to the leaf axis have brown hairs. Dioecious. In April and May, panicles are formed at the ends of the branches, and many small, pale brown flowers bloom. There are no petals, and the calyx is small and four-lobed. The male flowers have two stamens, and the female flowers have one pistil. The fruit is oblanceolate, 3-4 cm long, has narrow wings, and hangs down. It grows in mountain wetlands and is distributed in Honshu from the Chubu region northward. In the Hokuriku region, there is a closely related species called Fraxinus longiflorus, which has thin fruits about 5 mm wide. The wood is dense, strong, and sticky, so it is used for sports equipment such as racket frames, as well as for agricultural tool handles and furniture. In the Hokuriku region, it is planted on the ridges of rice paddies as rice rackets.

There are about 60 species in the Fraxinus genus, which are widely distributed in the Northern Hemisphere. Other species in Japan include Ash (Aodamo), Fraxinus serrata, and Ash (Manchuria).

[Yoshio Kobayashi July 16, 2021]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

モクセイ科（APG分類：モクセイ科）の落葉高木。高さ6～15メートル。樹皮は滑らかで灰白色、枝は太い。葉は対生し、奇数羽状複葉で長さ20～30センチメートル。小葉は5～9枚、卵形または長楕円(ちょうだえん)形で長さ5～15センチメートル、先はとがり、縁(へり)に浅く切れ込む鋸歯(きょし)がある。裏面の主脈に開出した白毛があり、小葉が葉軸につく節に褐色の毛がある。雌雄異株。4～5月、枝先に円錐(えんすい)花序をつくり、細かい淡褐色の花を多数開く。花弁はなく、萼(がく)は4裂して小さい。雄花には雄しべ2本、雌花には雌しべ1本がある。果実は倒披針(ひしん)形で長さ3～4センチメートル、狭長な翼があり、垂れ下がる。山間の湿地に生え、中部地方以北の本州に分布する。北陸地方には、果実が細く、幅約5ミリメートルの近縁種ナガミトネリコがある。材は緻密(ちみつ)で強く、粘りがあるので、ラケットの枠など運動用具材に用いられ、農具の柄(え)、家具材ともする。北陸地方では、田の畦(あぜ)に稲架木(はさぎ)として植える。

　トネリコ属は約60種あり、北半球に広く分布する。日本には、ほかにアオダモ、シオジ、ヤチダモなどが分布する。

［小林義雄　2021年7月16日］

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