Yabumyoga - Yabumyoga

A perennial herb of the Commelinaceae family (APG classification: Commelinaceae). The stem is erect and has several alternate leaves, but the nodes of each leaf are close together, so they appear to be ring-shaped. The leaves are narrowly oblong, 20-30 cm long, 3-7 cm wide, with parallel veins, pointed tips, and rough upper surfaces. From July to September, the stems bear dense spiky inflorescences at the end of the stems, reaching a total height of 0.5-1 m. The inflorescences are branched in whorls over several tiers, and each branch bears flowers in a cymes. The stems and branches have short hairs and are somewhat sticky. Both hermaphrodite and male flowers grow on the same plant. The sepals are three, circular, thick, and white. The petals are three, ovate, about 5 mm long, white, and thin. There are six stamens. In bisexual flowers, the style protrudes from the center, but in male flowers the style is short and the ovary is degenerate and small. The ovary is initially white, turns brown as it develops, and when ripe it becomes spherical and shiny indigo blue, about 5 mm in diameter. Although it looks like a berry, the ovary wall is thin and later breaks irregularly. The seeds are black and have wart-like protrusions on their surface. It grows under warm temperate forests, and is distributed from the Kanto region and west of Honshu to Kyushu, southern mainland China, and Taiwan. The name comes from the fact that the leaves resemble those of myoga, but the myoga leaf arrangement is alternate in two rows, making it easy to distinguish.

[Takashi Yamashita June 18, 2019]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

ツユクサ科（APG分類：ツユクサ科）の多年草。茎は直立し、数枚の葉を互生するが、おのおのの葉の節は接近しているので輪状にみえる。葉は狭長楕円(だえん)形で長さ20～30センチメートル、幅3～7センチメートル、平行脈があって先はとがり、上面はざらつく。7～9月、茎の先に密錐(みっすい)花序をつけ、全体の高さ0.5～1メートルになる。花序は数段にわたって輪生状に枝をつけ、おのおのの枝は集散状に花をつける。軸と枝には短い毛があってやや粘る。同じ株に両性花と雄花がつく。萼片(がくへん)は3枚、円形で厚みがあり白色。花弁も3枚あり卵形で長さ約5ミリメートル、白色で薄い。雄しべは6本。両性花では花柱が中央に出ているが、雄花では花柱は短く子房も退化して小さい。子房は初め白色で、発達すると茶色になり、熟すると径が約5ミリメートルの球形で光沢のある藍青(らんせい)色になる。液果のようにみえるが子房壁は薄く、のちに不規則に破れる。種子は黒色で表面にいぼ状の突起がある。暖帯林の下に生え、関東地方以西の本州から、九州、および中国大陸南部、台湾に分布する。名は、葉がミョウガと似ているためであるが、ミョウガの葉序は2列互生なので明らかに区別できる。

［山下貴司　2019年6月18日］

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