Horsetail - Sugina

A summer-green fern of the Equisetaceae family. It is a herbaceous plant consisting of nodes and internodes. The rhizome runs long underground, and above-ground stems branch out from the nodes. There are two types of above-ground stems: spore stems and vegetative stems. The spore stems emerge in early spring, followed by vegetative stems. The spore stems are also called "tsukushi" (horsetail, head vegetable), and are a single fleshy, light brown stem with no branches, and sheaths with dark brown, ligulate leaves attached at each node. These are commonly called "hakama." At the top of the stem, a pine cone-shaped sporangium is attached. The vegetative stem is green, and at the nodes, ligulate leaves are attached in a sheath-like shape, and branches with nodes grow in whorls. It can be found in fields and roadsides everywhere.

Horsetail is a spring delicacy, and can be mixed with sesame and mustard, or simmered or pickled. Remove the stems and quickly rinse in boiling water with a pinch of salt to remove the bitterness before cooking. The vegetative stems contain anhydrous silicic acid, as well as excetonin, a type of saponin, and excetin, a type of alkaloid, and can be used as a folk remedy for diuretics.

Equisetum palustre has a sheath-like ligulate leaf with a white membranous tip, does not produce sporangia, and instead produces sporangia at the tip of the vegetative stem. It is found in cooler areas from the Chubu region of Honshu northward.

[Makoto Nishida]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

トクサ科の夏緑性シダ。草体で、節と節間部からなる。根茎は地中を長く走り、節から地上茎を分出する。地上茎には胞子茎と栄養茎の2型があり、早春に胞子茎が出たあとに栄養茎が出る。胞子茎は「つくし」（土筆、筆頭菜）ともいい、肉質で淡褐色の1本の茎で枝を出さず、節ごとに濃褐色の舌状の葉が合着した鞘(さや)がある。これを俗に「はかま」とよぶ。茎頂には松かさ状の胞子嚢穂(のうすい)をつける。栄養茎は緑色で、節から鞘状に合着した舌状葉と、節のある枝を輪生する。至る所の野原や道端にみられる。

　つくしは春の味覚で、ごまやからしで和(あ)えたり、煮物、ひたし物にする。はかまをとって、塩を一つまみ入れた熱湯でさっとあく抜きしてから調理する。また栄養茎は無水ケイ酸のほか、サポニンの一種エキセトニン、アルカロイドの一種エキセチンを含み、利尿に効く民間薬にもなる。

　イヌスギナE. palustreは鞘状の舌状葉の先端が白い膜質で、胞子茎をつくらず、栄養茎の先端に胞子嚢穂をつける。分布は、本州中部地方以北の涼しい地方。

［西田　誠］

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