Houttuynia cordata - Houttuynia cordata

Japanese: ドクダミ - どくだみ

A perennial plant of the family Houttuynia cordata (APG classification: Houttuynia cordata). It has a distinctive odor. The rhizome is white and runs horizontally. It is 20-50 cm tall. The leaves are alternate, cordate or broadly ovate, and purple on the underside. The lower part of the stipule is fused to the petiole to form a sheath. The inflorescence is terminal and spike-like, with four large white petal-like bracts at the base, and the whole plant looks like a single flower. The other bracts are linear and small. The flowers are small, bisexual, and lack perianth. There are three stamens, and the lower part of the filaments is fused to the ovary. The pistil is fused with three carpels and has three styles. The upper end of the ovary dehisces at the fruiting stage. There are many seeds. It grows in clusters in wetlands such as garden corners and shaded areas, and is widely distributed throughout Japan, as well as from Southeast Asia to the Himalayas. There is one species in one genus. The one with many bracts and which appears to be a double flower overall is called Yaedodokdami (Houttuynia cordata) and is cultivated for ornamental purposes.

[Yuji Omori July 20, 2018]

Medicinal

In Japan, the whole plant is called Juyaku (ten medicines) or Jyuyaku (heavy medicines) (in China it is called Juusai (russet cabbage) and Gyoseisou (fish stalk herb)) and is used to treat swelling, high blood pressure, pulmonary gangrene, pulmonary tuberculosis, colds, sinusitis, hemorrhoids, constipation, etc. due to its diuretic, antipyretic, pus-draining and detoxifying effects. The essential oil, which contains about 0.005%, has antibacterial and antifungal properties. Also, the distinctive odor of Dokudami is due to decanoyl acetaldehyde and lauraldehyde. The name Juyaku (ten medicines) is said to have come from the fact that raising horses with Dokudami has the effects equivalent to ten kinds of medicine.

[Motoo Nagasawa July 20, 2018]

Houttuynia cordata
It is one of the most well-known medicinal plants, and grows in clusters in wetlands such as garden corners and under the shade of trees. It flowers from June to July. What look like petals are actually bracts. ©Seishohmaru ">

Houttuynia cordata

Houttuynia cordata inflorescence
It grows in a spike shape, with small flowers growing densely on the flower stalk. There are four white bracts at the base, and the whole plant looks like one flower. ©Seishohmaru ">

Houttuynia cordata inflorescence

Houttuynia cordata flower (morphology)
©Yuichi Kadota ">

Houttuynia cordata flower (morphology)

Houttuynia cordata
The bracts have grown large. It is cultivated for decorative purposes. ©Seishohmaru ">

Houttuynia cordata

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

ドクダミ科（APG分類：ドクダミ科）の多年草。特有の臭気がある。地下茎は白く、横走する。高さ20～50センチメートル。葉は互生し、心臓形または広卵形、裏面は紫色を帯びる。托葉(たくよう)は下部が葉柄と合着して鞘(しょう)状となる。花序は穂状で頂生し、基部には白色で花弁状の大きな包葉が4枚あり、全体が一つの花のようにみえる。他の包葉は線形で小さい。花は小さく、両性で花被(かひ)を欠く。雄しべは3本、花糸の下部は子房と合着する。雌しべは3枚の心皮からなり合生し、花柱は3本。子房の上端は果実期に裂開する。種子は多数。庭隅や木陰などの湿地に群生し、日本全土、および東南アジアからヒマラヤにかけて広く分布する。1属1種。包葉が多数あり全体が八重咲きの花に見えるものをヤエドクダミ（ヤエノドクダミ）といい、観賞用に栽培される。

［大森雄治　2018年7月20日］

薬用

日本では全草を十薬(じゅうやく)、重薬(じゅうやく)ともよび（中国では蕺菜(じゅうさい)、魚腥草(ぎょせいそう)）、利尿、解熱、排膿(はいのう)、解毒の作用があるため、腫(は)れ物、高血圧症、肺壊疽(えそ)、肺結核、感冒、蓄膿症、痔(じ)、便秘などの治療に用いる。約0.005％含まれている精油には抗菌性、抗カビ性がある。また、ドクダミがもつ特異な臭(にお)いはデカノイルアセトアルデヒド、ラウルアルデヒドによる。なお、十薬の名は、ドクダミでウマを飼育すると、10種の薬に相当する効果があることから生まれたという。

［長沢元夫　2018年7月20日］

ドクダミ
代表的な薬用植物の一つで、庭隅や木陰などの湿地に群生する。花期は6～7月。花弁のようにみえるのは包葉©Seishohmaru">

ドクダミ

ドクダミの花序

ドクダミの花〔形態〕

ヤエノドクダミ

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例

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