わが国の本州、宮城県以南から四国・九州に分布しています。山地に生え、高さは25メートルにもなります。樹皮は灰褐色で縦に浅く割れ目が入ります。葉は長さ2センチほどの線形で、螺旋状または2列つきます。裏面には細くて白い気孔帯が2本あります。5月ごろ、前年枝の葉腋に雄花を、新枝の基部に雌花をつけます。果実は緑色の仮種皮に包まれ、翌年の9月ごろに熟して緑色のままで落下します。写真上・中1〜2は、北尾根の静馬ヶ原にあったもので、日本海側に見られる変種の「ちゃぼがや(Torreya nucifera var. radicans)」かもしれません。
イチイ科カヤ属の常緑高木で、学名は Torreya nucifera。英名は Japanese torreya。
The Japanese torreya (Torreya nucifera) belongs to Taxaceae (the Yew family). It is a tall evergreen tree that is native from Miyagi prefecture of Honshu south to Shikoku and Kyushu. This tree grows in mountains and it can reach about 25 m in height. The bark is gray-brown and slightly furrowed longitudially. The leaves are linear about 2 cm long, and arranged spirally or in double rows. They have two, narrow, white stomatal bands on the rear surfaces. The male flowers are borne at the new-branch axils and the female flowers are borne at the new-branch bases in May. The seeds are covered with green arils, ripen and fall without change in next September. The 1st to 3rd photos were taken at Shizumagahara on the north ridge of Mt. Ibuki and may be the variant "Chabo-gaya" (Torreya nucifera var. radicans) found on the Sea of Japan side.