かやのみを　かげばうかぶは　じょうもんびと

Kaya(torrea) an evergreen tree that grows up to 25m in height and 2m in diameter, and has a lifespan of 1000 years.  There are 4 species in China, 2 species in the United States, 1 species in Japan, and 7 species in the world. In Japan, they are distributed south of Iwate and Yamagata prefectures.  The growth of the tree is extremely slow, and therefore the grain is fine and robust, and the go board and shogi board of Kaya tree have long been prized by enthusiasts as the finest products.  It is said that Japanese Kaya existed in the Jomon period, and there are traces of eating Kaya nuts along with Tochi nuts.  It has spread throughout Japan since the Heian period, and was actually used as a preserved food to prepare for poor crops, and the oil squeezed from the fruit was used as cooking oil and kerosene.  Even now, Kaya nuts are used for roasting and eating, as well as for candy and sugar-covered sweets, and until a while ago, it was also used as an insecticide and Chinese medicine for the stomach.  Having such a history, it used to grow naturally in the mountains of Japan and was also close to temples and farmhouses, but since the Meiji era, logging has progressed, so Japan Kaya is now nearly extinct.

榧は高さ25ｍ、直径２ｍ程度にまで育つ常緑樹で、寿命は1000年にも及びます。中国に４種、アメリカに２種、日本に１種と、世界には７種の榧があり、日本では、岩手県、山形県以南に分布しています。榧の木の成長は極めて遅く、それ故に木目が細かく堅牢で、本榧の碁盤・将棋盤といえば、古くから最高級品として愛好家に珍重されています。日本の榧は縄文時代には存在していたといわれ、栃の実とともに榧の実が食べられた跡が残されています。日本各地に広がったのは平安時代からで、実は凶作に備える保存食料に、また実から搾った油は食用油や灯油に利用されました。今でも榧の実は、炒って食べたり、飴や砂糖掛けのお菓子などに使われているほか、少し前まで、お腹の虫くだしや漢方としても利用されました。そうした歴史を持ち、かつては日本の山々に自生し、お寺や農家の庭先などの身近なところにもあった榧ですが、明治以降に伐採が進んだため日本の榧は今絶滅に近い状態にあります。