【赤鬼のつぶやき C.W.ニコル】キハダ 英名The Amur Cork Tree(アムール・コルクツリー/学名Phellodendron amurense)

 キハダは英名The Amur Cork Tree(アムール・コルクツリー/学名Phellodendron amurense)、日本原産で私たちアファンの森でもよく目にします。樹皮は淡黄色の厚いコルク層ですが、外皮を切り取ると現れるのは薄い内皮、さらにその奥には木部と師部の間に形成層が存在します。形成層では成長のもととなる新しい細胞が次々に作られ、そこで生まれた軟組織は木や樹皮になり、二次成長を続けていくのです。和名の由来でもある鮮やかな黄色の内皮には、生薬である黄檗(おうばく)の主成分ベルベリンが多く含まれ、急性の細菌感染症の治療などに用いられます。








This tree, also known in English as The Amur Cork Tree is native to Japan and quite common in our Afan woods. The outer bark is thick, buff-coloured cork, but if you cut that away to reveal the cambium, the thin, formative layer between the xylem and the phloem that gives rise to new cells and is responsible for secondary growth, in other words the soft tissue from which new wood and bark grows, you uncover a bright yellow layer, which gives the tree its Japanese name. This cambium layer is especially rich in bereberine, treatment for acute bacterial infection.
The kihada tree can grow to fifteen or so metres in height. It has feathery, sawtooth compound leaves that turn a beautiful yellow in autumn. It produces small black fruits from yellow blossoms that hang down in clusters.
Kihada wood is used for many things, including chopsticks and ‘go’ bowls.
The bark is also used to produce a dye that repels insects and has proved to be invaluable in the preservation of important documents.
When I first came to live here in Kurohime, and spent a lot of time hiking around the local mountains with the local members of the Hunting Association, including a lot of drinking afterwards, I was always being given packets of kihada bark to help with the hangovers. I believe that it helped but mostly I remember the incredibly bitter taste.
Since then, just a little research turns up a great deal of information on the healing powers of kihada. Basically it helps to heal skin and mucous membranes, and is traditionally used both internally and externally. It helps to increase the production of white blood cells and is supposed to be able to kill E coli, among other things.
There is as huge amount of interest and research done on the healing properties of forest plants, but one over-riding factor is quality control.
Whatever, the kihada is a wonderful tree to have in the woods.

May . 2019